Advice on doing a 2Pac Finish

[Tegmark]

Are there certain woods that shouldn't be finished in 2pac automotive clear?

I'm considering 2Pac because it's durable & visually good enough for me. I like how easy it is too polish out too.

But since there is no smooth primer underneath but a rough surface, has anyone finished it on veneer or ply for a mirror finish? How did you deal with the excessive holes & defects that veneer & ply have?

At first I thought about simply applying alot more coats until it's filled up every small nook & cranny in the wood? Are there any drawback to applying alot more coats? Solvent issues? or the clear looking too dark?


thanks

[Simplicity]

I've never used 2pac on wood.
On cars heaps.
I would say you would need to grain fill first
To try and get an even flat surface then sand to at least 400 grit I imagine.
It is something of late I've been wanting to try.
So I would be interested to hear how you go.

[Tegmark]

I've never used 2pac on wood. On cars heaps. I would say you would need to grain fill first To try and get an even flat surface then sand to at least 400 grit I imagine. It is something of late I've been wanting to try. So I would be interested to hear how you go.I'm not sure on what I should go, interior or automotive 2pac? Are both pretty much the same durability & gloss polished or non polished? Can 2Pac be applied over typical wood fillers & stains? I'm looking at wattle 7008 for brush.

[q9]

I'm looking at wattle 7008 for brush.

That's my standard answer for "what finish should I us?" questions. It's great, and applied well with attention to prep and being clean, gives a nice finish. Very tough and durable too. No matter what you do, you'll need extra brushes though.

[Rod Gilbert]

I have used a lot of 2 pac clear on various timbers I always use sanding sealer to fill the grain until you have smooth surface to apply top coat much cheaper than using 2 pac to fill and quicker because of the fillers in sealer. I always used mirortone acid cure and had great results with it when sprayed don't know about brushing. Some timbers require a lot more to fill the grain than others.
Regards Rod.

[themage21]

I've currently got a northane marine grade 2 pack poly waiting for me to finish making up some slats for a cast iron/timber bench seat rebuild.

I emailed and rang the manufacturer of the finish and they gave me a detailed procedure for applying the finish.

Long and short of it is that the 2 packs aren't that different, except that you eat a brush every time you do a coat (unless you use LOTS of acetone for cleaning) and that for a super-dooper-UV-stable-retain-the-grain-colour-forever-only-needs-recoating-every-5-years-finish, you need to put at least 6 coats down. So you use a lot of poly and a lot of brushes.

With the auto finishes, you'd need to make sure that they are formulated to adhere to timber - they might need a clean, grease and oil free metal to bond to chemically. The paint manufacturer normally supplies an excess of detail for most people with regards to how to use their finishes. Most people don't follow every last sodding point, which is why it can be difficult to get paint warranties honoured, as the paint system either hasn't been applied or maintained as per instructions. Then again, sometimes there is a good reason for those silly points, one would assume that the manufacturer wouldn't got to the trouble of specifying a third acetone wash or doing a Hare Krishna chant during application for the fun of it (nor testing it to make sure that the finish actually requires it).

Bear in mind that many spray metal finishes are very thin, so to build them up properly you'll be talking lots of coats.

Wattyl 7008 is a flooring finish, which means that it should stand up to a fair bit of abuse.

Wattyl also issue a handy dandy info sheet from their website:

http://www.wattyl.com.au/export/download/product_datasheet/D5.07_Estapol_7008.pdf?pdf=%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A++++++++++++++++++++++++++++++++++++++++++++%252Fopencms%252Fexport%252Fdownload%252Fproduct_datasheet%252FD5.07_Estapol_7008.pdf%250D%250A++++++++++++++++++++++++++++++++++++++++++++%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509

assuming that that long chain of http address works.

Reading through it, it looks as though you can use over some fillers and not others. Well worth testing.

I'd hazard a guess that automotive finish is going to be metal focussed, lots of thin coats and hard as heck, so not really good for timber (too brittle).

[router]

I use veneer on a fairly regular basis and finish off the jobs by either grain filling or spraying with sanding sealer then sanding down to at least 400 grit and sometimes even more depending on the finish that i want. I then spray pre cat lacquer 3/4/5 coats and when that is done I wait 3/4 days for the lacquer to dry and harden and then cut the job back using wet and dry abrasive to attain an acceptable finish then cut and buff with cutting compound. It is extremely difficult to get a good finish by simply spraying more coats on to fill all the voids. If you keep spraying you cannot just fill the voids you are spraying the whole job, over time the voids will go but the finish will be very thick. 2 pack is also difficult to spray to an effective level and takes a lot of practice.
With sanding sealer, too many coats will also send some timbers grey so one needs to be careful.
Try this method on some timber and see what you think.

Good luck

Router

[Tegmark]

I've currently got a northane marine grade 2 pack poly waiting for me to finish making up some slats for a cast iron/timber bench seat rebuild.

I emailed and rang the manufacturer of the finish and they gave me a detailed procedure for applying the finish.

Long and short of it is that the 2 packs aren't that different, except that you eat a brush every time you do a coat (unless you use LOTS of acetone for cleaning) and that for a super-dooper-UV-stable-retain-the-grain-colour-forever-only-needs-recoating-every-5-years-finish, you need to put at least 6 coats down. So you use a lot of poly and a lot of brushes.

With the auto finishes, you'd need to make sure that they are formulated to adhere to timber - they might need a clean, grease and oil free metal to bond to chemically. The paint manufacturer normally supplies an excess of detail for most people with regards to how to use their finishes. Most people don't follow every last sodding point, which is why it can be difficult to get paint warranties honoured, as the paint system either hasn't been applied or maintained as per instructions. Then again, sometimes there is a good reason for those silly points, one would assume that the manufacturer wouldn't got to the trouble of specifying a third acetone wash or doing a Hare Krishna chant during application for the fun of it (nor testing it to make sure that the finish actually requires it).

Bear in mind that many spray metal finishes are very thin, so to build them up properly you'll be talking lots of coats.

Wattyl 7008 is a flooring finish, which means that it should stand up to a fair bit of abuse.

Wattyl also issue a handy dandy info sheet from their website:

http://www.wattyl.com.au/export/download/product_datasheet/D5.07_Estapol_7008.pdf?pdf=%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A++++++++++++++++++++++++++++++++++++++++++++%252Fopencms%252Fexport%252Fdownload%252Fproduct_datasheet%252FD5.07_Estapol_7008.pdf%250D%250A++++++++++++++++++++++++++++++++++++++++++++%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%250D%250A%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509%2509

assuming that that long chain of http address works.

Reading through it, it looks as though you can use over some fillers and not others. Well worth testing.

I'd hazard a guess that automotive finish is going to be metal focussed, lots of thin coats and hard as heck, so not really good for timber (too brittle).

Thanks, my knowledge is auto 2pac works well on metal with 2pac primer under it, & on bare hard wood. A grain filler is needed on some wood as the spray version is very thin. For some smaller projects I much prefer a brush over spray, for if in the end the results will be the same polished to high gloss. Not sure if you can just use thinners to clean a fine varnish style brush? Didn't expect them to get eaten by 2pac.
Off the spray would be better if you didn't want to cut & polish. Maybe that's a good idea as things like dust, oxidation will degrade a finish quicker if it's cut & polished. I don't really know.


EDIT: Forgot to add, is there much difference in durability & high gloss Pre-Cat Lacquer vs standard 2pacs? I think not at all.

[artful bodger]

You don't see many people spray automobiles with furniture grade lacquer. So why spray furniture with car lacquer?
Strangely enough though an automotive paint shop once told me that a particular brand single pac acrylic lacquer was excellent on timber. I used it on huon pine and it was anything but excellent.
The 2 pac furniture lacquer that I have used a lot is sprayed over a sanding sealer for open grain timbers. Gives a great finish but is rather expensive.
There are good single pac varieties available too which are simpler to use.

[Tegmark]

Id like to finish a car in a French polish look. :)

Anyway before I try some 2pac polyU with brush. I wonder if it's a good idea to just use a cheap disposable brush to build up the thickness? Then for the last coat just use a good varnish brush. As for the cleaner I think I will just have to experiment with either strong lacquer thinners or acetone both at bunnings. As long as my purdy white swan can be useable after 5-10 cleans, as they cost me $40. Lacquer thinners seems fine with oil based polyU, not sure with 2pack.

[BobL]

This is 3 coat of 7008 on an Oregon kitchen bench top.
I didn't want a glossy finish so I cut back the last coat with 800 grit wet and dry
It's not really designed to build up coats so you will need LOTS of coats to get any sort of depth with it.

This kitchen is 20 years old and its the 2nd re-coating of the bench tops - yes the floor needs doing.

387963

[Tegmark]

This is 3 coat of 7008 on an Oregon kitchen bench top.
I didn't want a glossy finish so I cut back the last coat with 800 grit wet and dry
It's not really designed to build up coats so you will need LOTS of coats to get any sort of depth with it.

This kitchen is 20 years old and its the 2nd re-coating of the bench tops - yes the floor needs doing.

387963

Wouldn't sanding back with only 800 expose the wood & allow all kinds of things to grow in a kitchen environment?

When you say lots of coats to get depth, how many? Wanting to know how this compares to oil based PolyU. That gets depth by about 6+ coats not thinned, depending on the grain of wood.

[Tegmark]

In regards to 7008.
1- I'm not sure about the re coat time, does this mean that during this window of time the top coat merges with bottom before the bottom completely cures? I'm confused as the sanding time is much smaller.


2- Long after the re coat time, can another coat be added provided the bottom is sanded back or is it advised to start over again removing the whole clear coat?


3- With Pot Life, what does 8hrs standard & 1hr fast mean in terms of mixing ratios?

[BobL]

Wouldn't sanding back with only 800 expose the wood
I thought that would be the case too because the surface is not that flat but it turns out would take hours to cut through 3 hardened coats of 7008 with plain 800 grit by hand. I only did it to take a bit of the gloss off. What happens on a kitchen bench over time is it loses it's gloss and gets scratched etc in high use areas so I reckon it looks worse when it's half glossy and half matt.


& allow all kinds of things to grow in a kitchen environment?
Nope - wood is naturally anti bacterial - it's in fact more anti bacterial than plastic, or any finish.
In the area around the coffee machine the bench top gets quite badly dinged from dropped cups and porta-filters,constantly wet/damp from hot water drips etc.
Some of the dents end up ~1 mm deep. I sanded as may out as I could with a belt sander before recoating.


When you say lots of coats to get depth, how many? Wanting to know how this compares to oil based PolyU. That gets depth by about 6+ coats not thinned, depending on the grain of wood. All I can say is after three coats it looked like one coat of PU to me. But of course I'm not really lathering it on to get depth.

[BobL]

In regards to 7008.
1- I'm not sure about the re coat time, does this mean that during this window of time the top coat merges with bottom before the bottom completely cures?
Probably

I'm confused as the sanding time is much smaller.
If you let it fully cure it's like a rock and sanding becomes much harder - hence the belt sander to get the dents out of the surface.



2- Long after the re coat time, can another coat be added provided the bottom is sanded back or is it advised to start over again removing the whole clear coat?
Complete removal is only for previous coats other than 7008.
The only trouble i had it attaching to an old coat was a couple of spots that were not clean.
When I recoated I did attack the old coat pretty savagely with a belt sander but that was just to get the dents out otherwise in not dented areas I just sanded it until it was smooth


3- With Pot Life, what does 8hrs standard & 1hr fast mean in terms of mixing ratios?
Sorry can't help you there.

[BobL]

BTW have a look at this
http://www.woodworkforums.com/f67/cyanide-polyurethane-finishes-184090#post1768182

[Tegmark]

Probably

If you let it fully cure it's like a rock and sanding becomes much harder - hence the belt sander to get the dents out of the surface.



Complete removal is only for previous coats other than 7008.
The only trouble i had it attaching to an old coat was a couple of spots that were not clean.
When I recoated I did attack the old coat pretty savagely with a belt sander but that was just to get the dents out otherwise in not dented areas I just sanded it until it was smooth


Sorry can't help you there.
Thanks BobL

[SPF]

Probably

If you let it fully cure it's like a rock and sanding becomes much harder - hence the belt sander to get the dents out of the surface.



Complete removal is only for previous coats other than 7008.
The only trouble i had it attaching to an old coat was a couple of spots that were not clean.
When I recoated I did attack the old coat pretty savagely with a belt sander but that was just to get the dents out otherwise in not dented areas I just sanded it until it was smooth


Sorry can't help you there.

+1

Be careful of the temperature and humidity when using 7008. I have used this product extensively for furniture, architraves, and other bits and pieces. I am careful with the mix ratio (digital scales) and I have found that despite the claimed pot lift of 8 hours, it varies considerably. The hotter and drier it is, the faster it tends to gel. Also, take note of the manufacturer's warning about Part B degrading once opened. My experience has been that the older the Part B is (after opening) the faster it gels once mixed. I've had 7008 gel and become unusable within 2 hours in hot dry whether when the Part B can was opened a week or two prior.

I always wet sand between coats with a small amount of biodegradable detergent in the water, and then wipe down with a damp cloth.

In case you haven't found it, the specification sheet can be found here: http://lpb-dev.azurewebsites.net/Uploads/TDS/D5.07%20Estapol%207008.pdf

I hope that helps.

[Tegmark]

+1

Be careful of the temperature and humidity when using 7008. I have used this product extensively for furniture, architraves, and other bits and pieces. I am careful with the mix ratio (digital scales) and I have found that despite the claimed pot lift of 8 hours, it varies considerably. The hotter and drier it is, the faster it tends to gel. Also, take note of the manufacturer's warning about Part B degrading once opened. My experience has been that the older the Part B is (after opening) the faster it gels once mixed. I've had 7008 gel and become unusable within 2 hours in hot dry whether when the Part B can was opened a week or two prior.

I always wet sand between coats with a small amount of biodegradable detergent in the water, and then wipe down with a damp cloth.

In case you haven't found it, the specification sheet can be found here: http://lpb-dev.azurewebsites.net/Uploads/TDS/D5.07%20Estapol%207008.pdf

I hope that helps.

Thanks. Man those times going gel sound pretty bad. Good to know though. In summer I usually store stuff that was opened under the house where its cold & dry.

[Tegmark]

For those who use 7008, do you bake your project after a coat to speed up the curing time? Can this be done safely like 2pack in the automotive industry? Besides saving time, it would allow to use the left over already mixed parts A & B which are said to only have a pot life of 8hrs.

Do you even bother with re-coat times? Or just feel if it's not sticky to the touch you can just sand & add another coat?

[SPF]

For those who use 7008, do you bake your project after a coat to speed up the curing time? Can this be done safely like 2pack in the automotive industry? Besides saving time, it would allow to use the left over already mixed parts A & B which are said to only have a pot life of 8hrs.

Do you even bother with re-coat times? Or just feel if it's not sticky to the touch you can just sand & add another coat?

I have never baked 7008 and never would. The thing to be careful of when baking timber (apart from isocyonate, flamability hazards, and ensuring that the temperature of the work piece is below 35 degrees when you put on the next coat) is relative humidity and moisture content in the timber.

If you heat it up too much the moisture near the surface under the paint can cause delamination and make the finish look milky/cloudy.

If you have a ventilated powder coating oven or paint booth that you can try it out in, I'd be interested to see your results - but I suggest doing it on a couple of scrap pieces before painting a family heirloom or anything else of value. Like most 2 pack paints you have to use adequate safety measures - the MSDS can be searched for here: Product Finder : Valspar Professional (http://valsparprofessional.com.au/product-finder/)

[Tegmark]

I have never baked 7008 and never would. The thing to be careful of when baking timber (apart from isocyonate, flamability hazards, and ensuring that the temperature of the work piece is below 35 degrees when you put on the next coat) is relative humidity and moisture content in the timber.

If you heat it up too much the moisture near the surface under the paint can cause delamination and make the finish look milky/cloudy.

If you have a ventilated powder coating oven or paint booth that you can try it out in, I'd be interested to see your results - but I suggest doing it on a couple of scrap pieces before painting a family heirloom or anything else of value. Like most 2 pack paints you have to use adequate safety measures - the MSDS can be searched for here: Product Finder : Valspar Professional (http://valsparprofessional.com.au/product-finder/)

Thanks SPF, I didn't think about the moisture in wood. But what if the whole wood is 'sealed' by clear & its around 45C temp? Seems like an easy to achieve temp without being too high.



I have some other Q's about 7008, I assume you should sand it wet or dry with gloves to protect from the isocyanates unless it's fully cured?

If the mixed parts are stored in a sealed jar can they still be used a day or two later at room temp? My mixed parts haven't gone hard in the sealed jar yet.


Finally, would 7008 be great for outdoor UV, heat & cold exposure? If not what other easy applied products in 2pack are there? For the record oil based canned PolyU is terrible outdoors. In 2years outside on side of house it flaked off wood looking soo bad.

[SPF]

I have always sanded back to timber before applying the 7008, so I don't know about baking sealed timber. Like I said, if you go ahead and try it I'd be interested to know your results.

I sand it with a little water with some biodegradable detergent in it, and then wipe it clean with a damp cloth. At times the 7008 can be a little tacky even when it is fully cured. Tacky is probably overstating it, more like it is grippy on the sand paper. The detergent cleans the surface and makes sanding a lot easier.

I think I'm misreading your question about mixed parts. My mixed 7008 (Part A and Part B) always gels within the stated 8 hour pot life, so no you can't use it days later. If your mixed paint is not gelling within this time there is something wrong.

If you have a look at the spec sheet it states that it is an indoor paint only. I (and my family) have used 7008 on window frames inside, but that are exposed to direct sunlight for hours a day. All of these have lasted for more than 10 years. Some have started to become less clear but the paint is still intact, and a couple have cracked where the timber is subject to significant thermal cycling.

My preference for clear finishes outside are either a quality latex acrylic (easy) or using epoxy resin as a base coat and then finishing it in a marine 2pac polyurethane (difficult, costly, and risk to health). In cases where I do the latter, I also use a light fibreglass cloth with the epoxy to protect the timber from gashes and scratches that allow moisture into the timber - its a lot of work, but if you do it properly, you don't have to do it again for a decade or two.

I hope that helps.

[ian]

3- With Pot Life, what does 8hrs standard & 1hr fast mean in terms of mixing ratios?
while not specific to 7008, with SystemThree epoxy adhesives / finishes, the hardener is rated as fast, normal, or slow. The idea is that at low temperature you use the fast hardener to pull the curing time back to something reasonable (like 6 to 8 hours), while at higher temps you use the slow hardener to push the pot life out to something reasonable (like 30 to 40 minutes).
In terms of mixing ratios, the different hardeners are formulated in a way to keep the mixing ratio constant regardless of which hardener you are using.

[BobL]

Thanks SPF, I didn't think about the moisture in wood. But what if the whole wood is 'sealed' by clear & its around 45C temp? Seems like an easy to achieve temp without being too high.

A hot shed in summer would reach that temp, you could always try that. On a quality piece of furniture I would be worried by the wood expansion and shrinkage between 45 and 20ºC as epoxy is generally not as flexible as PU.

The first time I recoated our kitchen bench it was the middle of summer and because of the sanding and fumes involved I turned off the air-conditioner and opened up the windows and i remember over the 3 days it took it was stinking hot and the inside temperature reached >28º. The next time was the end of May and as we run no heating appliances in our house and let it cool right down it was much cooler probably around 17º. I don't recall any significant differences in curing time between the two coatings.

To sand the bench the first time I used a Makita belt sander with the crappy little dust bag and the just filled the house up with dust.
The second time I attached a shop vac with a dust exit port and attached some 2" hose to that and dangled that out a window and this made a big difference.
I then did the same with the ROS between subsequent coats although I did mostly wet sanding.


I have some other Q's about 7008, I assume you should sand it wet or dry with gloves to protect from the isocyanates unless it's fully cured?
I don't know where I read it but I seem to recall reading that when you can't smell it this means the solvent is basically gone and the cyano is locked into the material
I know what feels like to be poisoned by 7008 by handling it when its wet and have also sanded it wet or dry with bare hands immediately after the prescribed sanding time and have felt no effects.
Cyano poisoning is interesting because if you are only exposed to very low levels (which is the case with 7008 absorption through the skin) you can feel the preliminary effects (tingling finger tips and lips) well before you reach a toxic dose.


If the mixed parts are stored in a sealed jar can they still be used a day or two later at room temp? My mixed parts haven't gone hard in the sealed jar yet.
Just because they haven't gone hard doesn't mean it will flow properly when applies.


Finally, would 7008 be great for outdoor UV, heat & cold exposure? If not what other easy applied products in 2pack are there? For the record oil based canned PolyU is terrible outdoors. In 2years outside on side of house it flaked off wood looking soo bad.
7008 like EVERYTHING else is hopeless outside on timber. Remember timber is not like metal and moves even when sealed. Eventually cracks develop and water gets in and you know the rest.

[Tegmark]

I have always sanded back to timber before applying the 7008, so I don't know about baking sealed timber. Like I said, if you go ahead and try it I'd be interested to know your results.

I sand it with a little water with some biodegradable detergent in it, and then wipe it clean with a damp cloth. At times the 7008 can be a little tacky even when it is fully cured. Tacky is probably overstating it, more like it is grippy on the sand paper. The detergent cleans the surface and makes sanding a lot easier.

I think I'm misreading your question about mixed parts. My mixed 7008 (Part A and Part B) always gels within the stated 8 hour pot life, so no you can't use it days later. If your mixed paint is not gelling within this time there is something wrong.

If you have a look at the spec sheet it states that it is an indoor paint only. I (and my family) have used 7008 on window frames inside, but that are exposed to direct sunlight for hours a day. All of these have lasted for more than 10 years. Some have started to become less clear but the paint is still intact, and a couple have cracked where the timber is subject to significant thermal cycling.

My preference for clear finishes outside are either a quality latex acrylic (easy) or using epoxy resin as a base coat and then finishing it in a marine 2pac polyurethane (difficult, costly, and risk to health). In cases where I do the latter, I also use a light fibreglass cloth with the epoxy to protect the timber from gashes and scratches that allow moisture into the timber - its a lot of work, but if you do it properly, you don't have to do it again for a decade or two.

I hope that helps.

Hi, I have stored many pieces in oil based in my shed in summer taking a beating the whole time sealed all around asap after buying the wood. Most of the surface looks fine, apart from some small cracks near wood joins. Wouldn't do it again now.

7008 not fully cured seems the same to sand as oil based. Thanks for your advice

[Tegmark]

7008 like EVERYTHING else is hopeless outside on timber. Remember timber is not like metal and moves even when sealed. Eventually cracks develop and water gets in and you know the rest.

Thanks I think its the wild swings of cold & hot & not the constant UV that kill the clear.

[Tegmark]

Some more Q's I have.

When should I cut & polish 7008 to a high gloss? Or any 2pac PolyU. Before it's fully cured or after? I'm worried if I wait until fully cured it might be soo hard & the required polishing could cause problems. Even oil based PolyU fully cured takes along time to polish up, the results are inconsistent.

When cleaning Brushes with 2pac PolyU, I noticed going through thinners like water & it evaporates too quickly before the detergent can wash it all away, I thought at the end to just use turps & hopefully it would be strong enough to clean the left overs. Turps is cheap, stays wet & washes away well with detergent. Not sure if this is a good idea with 2pac & expensive brushes?

[q9]

Turps is useless with 7008. Acetone. My work system with 7008 cleaning is 3 jars of reducer, and lots of rags/newspaper to clean the brush. Finally soak in acetone. But still, be prepared to chuck brushes more frequently than you'd like. Part of the deal.

[Tegmark]

Turps is useless with 7008. Acetone. My work system with 7008 cleaning is 3 jars of reducer, and lots of rags/newspaper to clean the brush. Finally soak in acetone. But still, be prepared to chuck brushes more frequently than you'd like. Part of the deal.

If the thinners has had a chance to dissolve & flush most of the 2pac, I should think turps will bridge the gap between thinners & detergent well. I will have to try.

From experience cleaning thick varnish brushes with oil based, You have to be relentless cleaning the brush far more then 3 times. & flick violently to get the left overs in the Bristols out.

[q9]

3 washes and a soak in acetone worked ok for me...but make no mistake, after the job is done, the brushes get tossed. Anyhow, I am not prescriptive, if it works I'd like to hear about it. I love 7008. But it can be a hassle to use.

On an earlier topic, I did once use it to refinish a pine table that we had out side on the verandah. It got lots of sun and a pot plant dripping on it for about 10-15 years. The wood cracked along some joins but the finish held up quite well.

[SPF]

If the thinners has had a chance to dissolve & flush most of the 2pac, I should think turps will bridge the gap between thinners & detergent well. I will have to try.

From experience cleaning thick varnish brushes with oil based, You have to be relentless cleaning the brush far more then 3 times. & flick violently to get the left overs in the Bristols out.

Turps doesn't work by itself. Let us know if you find a combination that does.

I know that for epoxy a mix of acetone and metho is effective and far cheaper than just using acetone - I have never tried with 7008. Also for epoxy, white vinegar works as epoxy is basic and the vinegar neutralises it. Again I haven't tried this with 7008 either.

I have found that the test pot Monarch brushes ($2.50 for a pack of 2) are good for detail work, so I just use these as consumables.

[Tegmark]

3 washes and a soak in acetone worked ok for me...but make no mistake, after the job is done, the brushes get tossed. Anyhow, I am not prescriptive, if it works I'd like to hear about it. I love 7008. But it can be a hassle to use.

On an earlier topic, I did once use it to refinish a pine table that we had out side on the verandah. It got lots of sun and a pot plant dripping on it for about 10-15 years. The wood cracked along some joins but the finish held up quite well.

What brushes do you use that get tossed after a job? I was able to clean a thick varnish brush after 2pac & it seems no different cond than before, however cheapo brushes I would toss.

[Tegmark]

Turps doesn't work by itself. Let us know if you find a combination that does.

I know that for epoxy a mix of acetone and metho is effective and far cheaper than just using acetone - I have never tried with 7008. Also for epoxy, white vinegar works as epoxy is basic and the vinegar neutralises it. Again I haven't tried this with 7008 either.

I have found that the test pot Monarch brushes ($2.50 for a pack of 2) are good for detail work, so I just use these as consumables.

I was trying turps after about 3-5 cleans in thinners, the hope was that whatever diluted 2pac is left in the dense brush would came out by turps which would stay wet long enough to wash away with detergent. However I think after thinners, an hour or soak in a bit of acetone then detergent rinsing might be good enough.

[Tegmark]

It seems that using a 3" china swan style brush with 7008 is alot worse & harder than just a small $3 1.2" bunnings varnish brush. The results were pretty bad with my swan. Unlike Oil based which I could lay a thick coat down like glass, it seems that this can't be done with 2pac.


Because, the thick dense brush just absorbs the clear making it very hard to get a thick wet glass like coat, second, the 2pac sets very quickly even at room temp unlike oil based, this results in the brush bristles being a bit hard holding in alot of clear & producing a dry coat with excessive pinholes. Compared to oil based the bristles stayed soft & smooth producing minimal pinholes. Also handling a large brush like this takes time. So any chance of an off the brush finish with this stuff is not gonna happen I think.
I didn't notice how quickly this stuff sets as I was using a small brush that enabled me to quickly lay down a thick coat before it sets.

But this stuff is amazing, how think you can lay it down & the next day its pretty much able to sand.

[SPF]

The 7008 isn't promoted as a self leveling paint, but it definitely has a tendency to flatten out quickly and evenly. I have found it impossible to get a thick coat down, even on horizontal surface; and I never use less than 3 coats as I just can't get a good even finish with less. I have had problems with pin holes - make sure you haven't got an open container of silicone sealant near where you are painting and you haven't used silicone spray or ptfe spray nearby. Using silicone based car polish to cut the paint will also be a problem. All these things will make your life very difficult.

2 pac is great for getting a job done quickly.

[Tegmark]

The 7008 isn't promoted as a self leveling paint, but it definitely has a tendency to flatten out quickly and evenly. I have found it impossible to get a thick coat down, even on horizontal surface; and I never use less than 3 coats as I just can't get a good even finish with less. I have had problems with pin holes - make sure you haven't got an open container of silicone sealant near where you are painting and you haven't used silicone spray or ptfe spray nearby. Using silicone based car polish to cut the paint will also be a problem. All these things will make your life very difficult.

2 pac is great for getting a job done quickly.

Are you saying it's impossible with just large areas? And because it sets quickly? I got a thick coat down no problems on a small a4 area with a cheap 50mm brush. But the pinholes I speak of are caused by the bristles (I'm not sure why exactly). Basically when the 2pac sets on my thick brush, the bristles start acting like a non smooth aggressive bristle, which is exactly what causes the excessive pinholes.


I don't know for sure about silicone based products, I use meguiars M105 & M205 & they worked well on oil based. I will try 2pac once it fully cures. I beat it will come up mirror gloss like an auto paint job.

This stuff still looks pretty transparent after 6 thick coats. Love it.

[Tegmark]

When wet sanding with a large area block, you constantly need to clean away the rubbing water to prevent the huge friction encountered.


When applying thick coat, the clear at the edges right next to a 90degrees side of wood slightly bulge/rise up, making it more harder to sand as you have to sand those areas next to the edge first. I think maybe because 2pac has alot less solvent & more body?

Like in this illustration:

https://s32.postimg.org/9j6j2dtj5/wood.jpg (https://postimg.org/image/9j6j2dtj5/)

[Tegmark]

I was able to lay a thick coat down like glass, without a single pinhole, but after they start to form from most likely air trapped in the clear plus as I stated above the clear bulging at the sides when thick, there really seems to be no need or benefit at all using a large dense brush. The cost of solvent & gloves to clean one is huge too.

[SPF]

When applying thick coat, the clear at the edges right next to a 90degrees side of wood slightly bulge/rise up, making it more harder to sand as you have to sand those areas next to the edge first. I think maybe because 2pac has alot less solvent & more body?

Like in this illustration:

https://s32.postimg.org/9j6j2dtj5/wood.jpg (https://postimg.org/image/9j6j2dtj5/)

Interesting - thanks for posting that up. I have never got enough film thickness for that to happen with 7008. But it happens with just about all common 2 part resins. It is from a combination of the surface tension of the resin plus volumetric shrinkage due to the peak in temperature while the resin thermosets.

If you leave an amount of 7008 in a jar and let it set, you will notice that the resin will appear to climb up the sides of the jar, and once the temperature peaks, and it starts to cool and harden, the resin will pull away from the edges of the jar as it shrinks. The force that this generates can be a real problem with unsupported veneers or thin material if only painted/applied on one side.

[SPF]

I don't know for sure about silicone based products, I use meguiars M105 & M205 & they worked well on oil based. I will try 2pac once it fully cures. I beat it will come up mirror gloss like an auto paint job.

I got half way through responding to this and then lost the images I had to post up.

Silicone based products and ptfe spray lubricants can cause problems with paint as they interfere with adhesion and create orange peel and other similar issues, including pinholes. Just to be helpful, you don't even have to use these products on the job, or have any direct contact from contaminated tools - having an open container in the same room can cause problems. So, if you are getting seemingly random problems and you have prep'd appropriately then keep this in mind.

[Tegmark]

Interesting - thanks for posting that up. I have never got enough film thickness for that to happen with 7008. But it happens with just about all common 2 part resins. It is from a combination of the surface tension of the resin plus volumetric shrinkage due to the peak in temperature while the resin thermosets.

If you leave an amount of 7008 in a jar and let it set, you will notice that the resin will appear to climb up the sides of the jar, and once the temperature peaks, and it starts to cool and harden, the resin will pull away from the edges of the jar as it shrinks. The force that this generates can be a real problem with unsupported veneers or thin material if only painted/applied on one side.

Thanks SPF, good to know that from now on. Back to experimenting.
:)

[Tegmark]

I got half way through responding to this and then lost the images I had to post up.

Silicone based products and ptfe spray lubricants can cause problems with paint as they interfere with adhesion and create orange peel and other similar issues, including pinholes. Just to be helpful, you don't even have to use these products on the job, or have any direct contact from contaminated tools - having an open container in the same room can cause problems. So, if you are getting seemingly random problems and you have prep'd appropriately then keep this in mind.

These pinholes are I think from air dissolved in the clear from the bristles working the clear, not that it matters in many cases as when thick the sides bulge up ruining any chance of an off the brush perfect finish.

[ian]

if I recall 7008 is designed to go on with a relatively thin wet film. The bulges yiu describe sound like a surface tension effect that might go away if the edges of your piece are "broken" or rounded

[SPF]

Thanks SPF, good to know that from now on. Back to experimenting.
:)

Tegmark how did you go sanding and polishing the 7008? The 7008 is pretty good straight off the brush for clarity and shine, but I haven't tried polishing it. I'm keen to see your results, especially if you are doing a broad flat surface.

I'm looking at making a large American oak table in the next couple of months, and am considering either the epoxy and marine PU, or the 7008. I'd like to spray it for even finish, but if the 7008 can be polished, then that would be a quicker and simpler solution.

[Tegmark]

if I recall 7008 is designed to go on with a relatively thin wet film. The bulges yiu describe sound like a surface tension effect that might go away if the edges of your piece are "broken" or rounded

I tried to brush a coat of 7008 straight out of the can as thin as I could (any thinner & it's hard to apply as its dry & doesn't spread easy). Yet this problem still happens. My guess 2pack was never really good on a brush & its mainly for floorboards etc.

[Tegmark]

Tegmark how did you go sanding and polishing the 7008? The 7008 is pretty good straight off the brush for clarity and shine, but I haven't tried polishing it. I'm keen to see your results, especially if you are doing a broad flat surface.

I'm looking at making a large American oak table in the next couple of months, and am considering either the epoxy and marine PU, or the 7008. I'd like to spray it for even finish, but if the 7008 can be polished, then that would be a quicker and simpler solution.


Hi SPF,

Just waiting for a week or two more so it really hardens up, as I applied the coats pretty thick. So far I just finished sanding from 400 all up to 2000 through the grits. Seems easy enough as long as new paper is used.

When I polish, Ill post my results. I intend to do a full hand polish & machine. If it's anything like oil based, it should come up very glossy but look more plastic/opaque on certain angles.

[Tegmark]

Does anyone know if you can 2pack PolyU over water based wood filler? I tried a test piece & it's been a week or more & no issues so far.

[ian]

I tried to brush a coat of 7008 straight out of the can as thin as I could (any thinner & it's hard to apply as its dry & doesn't spread easy). Yet this problem still happens. My guess 2 pack was never really good on a brush & its mainly for floorboards etc.from the Estapol 7008 Technical data sheet

recommended Wet Film thickness 85 microns ( = 0.085 mm)
recommended Dry Film thickness 38 microns ( = 0.038 mm)


Data sheet http://lpb-dev.azurewebsites.net/Uploads/TDS/D5.07%20Estapol%207008.pdf

[SPF]

Does anyone know if you can 2pack PolyU over water based wood filler? I tried a test piece & it's been a week or more & no issues so far.

I have a danish couch frame that I used water based filler on with 7008 over the top. This was done 6 years ago and no problems (except the filler lightened over time and is now obvious).

[SPF]

When I polish, Ill post my results. I intend to do a full hand polish & machine. If it's anything like oil based, it should come up very glossy but look more plastic/opaque on certain angles.

I look forward to seeing the results.

[Tegmark]

from the Estapol 7008 Technical data sheet

recommended Wet Film thickness 85 microns ( = 0.085 mm)
recommended Dry Film thickness 38 microns ( = 0.038 mm)


Data sheet http://lpb-dev.azurewebsites.net/Uploads/TDS/D5.07%20Estapol%207008.pdf


These tech specs are for generic floor boards & not a fine furniture application. Any thickness & the problem happens. As far as I can tell 2pack is only good for spraying.

[ian]

The recommended wet film thickness for Estapol water based Xtra clear is 83 microns, which is near enough the same as for 7008.
and that for Estapol Moisture Cure Polyurethane High Gloss is 100 microns, which is much thicker.
So I'm wondering if you are applying too thick a coat of 7008 which is leading to your problems.


It might be worth a call or email to Wattyl's technical help line

[Tegmark]

The recommended wet film thickness for Estapol water based Xtra clear is 83 microns, which is near enough the same as for 7008.
and that for Estapol Moisture Cure Polyurethane High Gloss is 100 microns, which is much thicker.
So I'm wondering if you are applying too thick a coat of 7008 which is leading to your problems.


It might be worth a call or email to Wattyl's technical help line


Thanks ian.

I wan't to first try applying coats that are thinned. So I wan't to ask what is the recommended thinning %? 10%, 15%?

I'm going to try 10-15% to see how I go with this problem.

thanks

[ian]

7008's technical data sheet, suggests 10% as the upper limit for thinning.

also, how cold is it where you are working? Could low temperature be an issue.

[ian]

These tech specs are for generic floor boards & not a fine furniture application. Any thickness & the problem happens. As far as I can tell 2pack is only good for spraying.
CAUTION

The safety data for Estapol 7008 specifically says -- "Do not apply this product using spray equipment."

[SPF]

CAUTION

The safety data for Estapol 7008 specifically says -- "Do not apply this product using spray equipment."

Many 2pac products need to be sprayed with a grounded gun, and need to have adequate fan forced ventilation - given the purpose of 7008 (floors and timber more generally) it makes more sense to say that it shouldn't be sprayed.

It may also suffer from other problems, but explosion hazard is a good enough reason not to spray it.

[Tegmark]

7008's technical data sheet, suggests 10% as the upper limit for thinning.

also, how cold is it where you are working? Could low temperature be an issue.


I doubt it. I have applied in a broad range of temp. I get the same results even at 12 degrees C as I do near 30C.

[Tegmark]

Many 2pac products need to be sprayed with a grounded gun, and need to have adequate fan forced ventilation - given the purpose of 7008 (floors and timber more generally) it makes more sense to say that it shouldn't be sprayed.

It may also suffer from other problems, but explosion hazard is a good enough reason not to spray it.

As I understand there isn't much difference between 7008 to 2pack polyu in the auto trade. I bet it could be thinned down & sprayed no problems with a good setup. If there is explosive risk with spraying, it would be the same for diy spray painters in their garage id imagine.

[Tegmark]

What do you guys use for filling deep cracks when you wan't it see thru? I tried to use some 2pack clear, but I get occasional air bubbles stuck in the voids & it takes many coats to fill the cracks as it tends to rise up out of the cracks onto the wood surface.

I'm reading about sellys araldite epoxy glue. Might try that & hope its as transparent as my clear method.

[ian]

As I understand there isn't much difference between 7008 to 2pack polyu in the auto trade. I bet it could be thinned down & sprayed no problems with a good setup. If there is explosive risk with spraying, it would be the same for diy spray painters in their garage id imagine.
Tegmark

I really think you should read the MSDS for 7008. Perhaps the reason Valspar say "don't spray" is that one of 7008's components or atomised 7008 is a carcinogen?

[Tegmark]

Tegmark

I really think you should read the MSDS for 7008. Perhaps the reason Valspar say "don't spray" is that one of 7008's components or atomised 7008 is a carcinogen?

Your assuming I haven't read it. I'm aware of the carcinogen threat. I have a respirator, googles for doing it by brush in a unopened area. And if I was ever gonna spray it, I would have a setup like a spray painters garage.

[SPF]

I'm reading about sellys araldite epoxy glue. Might try that & hope its as transparent as my clear method.

I've had mixed results doing this. The worst being when I put it in a crack with a charred edge and the glue dripped over the high points and formed air gaps that were lighter than the char, which looked terrible. The best being when I used acetone to clean the area first with a ground down toothbrush (only one bristle tree wide) and once dry and vented, I overfilled the gap substantially and then vibrated it with a orbital sander until the glue gelled (5 - 10 mins). The trick with this is letting the glue set for the stated time so that it fully cures and shrinks before you cut it back and sand it. As with all epoxy it is still pretty gummy under the sand paper though. If you want it clear, get the ultra clear product.

I've also used epoxy resin and araldite with wood flour to make a filler paste. My tip for this is to use a very sharp blade to trim it down within about 30 minutes of setting. Otherwise it is too hard to cut down without damaging the surrounding area.

I hope that saves you some time and sanding.

[SPF]

If you want it clear, get the ultra clear product.

Araldite® Ultra Clear | Selleys Australia (http://www.selleys.com.au/trade/specialist-products/epoxy-adhesives-fillers/araldite-ultra-clear/)

[Tegmark]

I've had mixed results doing this. The worst being when I put it in a crack with a charred edge and the glue dripped over the high points and formed air gaps that were lighter than the char, which looked terrible. The best being when I used acetone to clean the area first with a ground down toothbrush (only one bristle tree wide) and once dry and vented, I overfilled the gap substantially and then vibrated it with a orbital sander until the glue gelled (5 - 10 mins). The trick with this is letting the glue set for the stated time so that it fully cures and shrinks before you cut it back and sand it. As with all epoxy it is still pretty gummy under the sand paper though. If you want it clear, get the ultra clear product.

I've also used epoxy resin and araldite with wood flour to make a filler paste. My tip for this is to use a very sharp blade to trim it down within about 30 minutes of setting. Otherwise it is too hard to cut down without damaging the surrounding area.

I hope that saves you some time and sanding.

Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

[SPF]

Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem (http://dalchem.com.au/how-to/polyurethane-casting-resins/)
Easycast Clear Resin (http://www.barnes.com.au/polyurethane/easycast-clear-1312)

There are also equivalent epoxies:
Solid Solutions - Casting Resins (http://www.solidsolutions.com.au/view_products.php?cat=6)

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

[SPF]

Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem (http://dalchem.com.au/how-to/polyurethane-casting-resins/)
Easycast Clear Resin (http://www.barnes.com.au/polyurethane/easycast-clear-1312)

There are also equivalent epoxies:
Solid Solutions - Casting Resins (http://www.solidsolutions.com.au/view_products.php?cat=6)

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

[Tegmark]

The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem (http://dalchem.com.au/how-to/polyurethane-casting-resins/)
Easycast Clear Resin (http://www.barnes.com.au/polyurethane/easycast-clear-1312)

There are also equivalent epoxies:
Solid Solutions - Casting Resins (http://www.solidsolutions.com.au/view_products.php?cat=6)

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

Thanks. I tried epoxy resin & it was not good tbh. It always creates small air bubbles & is very hard to sand. Not as clear & see thru as the poly clear itself.

[SPF]

Thanks. I tried epoxy resin & it was not good tbh. It always creates small air bubbles & is very hard to sand. Not as clear & see thru as the poly clear itself.

If you are going to use Epoxy, sanding it back is horrible, its gummy when its not fully cured and very tough when it is. If you understand how much it will shrink in a given situation, the better option is to overfill it let it start to gel and then trim it back with a very sharp blade as far as you can. To set your trim height, you can use tape for cutting it back to within 0.15 - 0.25 mm or paper or card tacked down for anything thicker. You simply put the tape down along two edges and run the blade through the glue while the elevation is set bythe tape.

A cheap easy blade to use for this is a disposable box cutter blade glued onto a piece of timber to ensure it stays flat. Make sure the blade sits out at least 4 mm from the leading edge of the timber.

If you want a more permanent solution, you can also modify a plane (good reuse of a cheapy) or spoke shave to do this job. Or you can clamp a plane between two blocks of timber, with the plane set the correct elevation above the glue. If you are going to try a plane for this job, make sure you lubricate the blade so that it doesn't jam as you try to trim the glue back. Use a lubricant that can be easily cleaned off the glue (and timber) later. I use paraffin wax rubbed onto the blade as it lubricates the blade but generally doesn't get onto the parent material.

The other thing to mention is that pushing any blade through epoxy perpendicular to travel is difficult. If you have an approach angle of 35-50 degrees, I find that works well. You may still have to use a slight sawing action but it should take almost no effort.

I hope that helps.

[Tegmark]

If you are going to use Epoxy, sanding it back is horrible, its gummy when its not fully cured and very tough when it is. If you understand how much it will shrink in a given situation, the better option is to overfill it let it start to gel and then trim it back with a very sharp blade as far as you can. To set your trim height, you can use tape for cutting it back to within 0.15 - 0.25 mm or paper or card tacked down for anything thicker. You simply put the tape down along two edges and run the blade through the glue while the elevation is set bythe tape.

A cheap easy blade to use for this is a disposable box cutter blade glued onto a piece of timber to ensure it stays flat. Make sure the blade sits out at least 4 mm from the leading edge of the timber.

If you want a more permanent solution, you can also modify a plane (good reuse of a cheapy) or spoke shave to do this job. Or you can clamp a plane between two blocks of timber, with the plane set the correct elevation above the glue. If you are going to try a plane for this job, make sure you lubricate the blade so that it doesn't jam as you try to trim the glue back. Use a lubricant that can be easily cleaned off the glue (and timber) later. I use paraffin wax rubbed onto the blade as it lubricates the blade but generally doesn't get onto the parent material.

The other thing to mention is that pushing any blade through epoxy perpendicular to travel is difficult. If you have an approach angle of 35-50 degrees, I find that works well. You may still have to use a slight sawing action but it should take almost no effort.

I hope that helps.

Thanks good info there. I will experiment. In the meantime while I wait for some stuff to arrive I thought about my plan to get polyu to a high gloss. This is my basic plan.

Hand polish method: Finish with the finest grit sand paper, atm I have 5000grit but heard about up to 12000. Then compound & polish with foam pads. To me hand method is the most important as wood usually is too delicate for any machine work. Since there are sharp edges that wool will cut thru straight away, curved edges etc that a machine will have a high chance of cutting thru.

Machine method: Cut with a rotary buffer w/ double sided wool pad & also swansdown mop. Then use a d/a polisher with cutting & polishing foam pads. More suited for open large areas like a table top. I found the rotary has so much more cut power than a mop on a drill that you really need heaps of experience to use without damaging the clear.

Machine & Hand method: Cut with wool to save alot of time & polish up with hand foam pads. I did this with oil based polyu & it took a while being tough.

[SPF]

Tegmark I look forward to seeing the results.

If you are going to use 2000 grit plus paper make sure you wipe the surface clean between each grade of paper and tack cloth it. It is a real pain if you pick up a loose 1000 grit when using 5000 or higher and it ruining all your work.

[Tegmark]

Tegmark I look forward to seeing the results.

If you are going to use 2000 grit plus paper make sure you wipe the surface clean between each grade of paper and tack cloth it. It is a real pain if you pick up a loose 1000 grit when using 5000 or higher and it ruining all your work.

Thanks. I think finishing off with 5000grit looks pretty good, 50/50 matte/gloss.

[Tegmark]

From all the testing I have done in past few weeks:
- Cheapo brushes are not worth it. My purdy ox hair gives less pinholes than the cheapos. However, thin cheapo does a decent job with very thick coats as you have plenty of film to sand and this brush requires very small acetone to clean.
- There seems to be no reason why a varnish brush gets thrown out after the job, after a dozen or so uses my ox hair seems as good as it was when new.
- Whether coats were very thick, thin, or thinned by 10%. they all bulged up right near edge of wood.
- I found it utterly impossible to work with thin coats as they simply are not thick enough to rub out the pinholes and bulges near edge of wood without causing witness lines and rubbing into stain.
- Unless the surface of wood is perfect like blocked out high build primer and your spraying 3-4 thin coats, the only way i finished a test piece was 5-6 thick coats, thick enough if vertically would result in major runs.
- Visually there doesn't seem to be much diff at all between 3-4 thin coats vs 5-6 very thick. except the latter has a bit more depth perhaps.
- Even if you brush it on like glass without a visual flaw, 30-60mins later pinholes appear probably from the chemical reactions.
- For reasons I don't know, there is always a slight ripply reflection with say a light source while moving against the grain as appose to moving with it. This happens with off the brush, sanded to 5000grit or polished up. whether coats are thick, thin or not brushed. I'm not really sure if this is the grain causing this like an optical effect or just something that plastic poly does? I will try shellac & lacquer one day to see.

[SPF]

From all the testing I have done in past few weeks:
- For reasons I don't know, there is always a slight ripply reflection with say a light source while moving against the grain as appose to moving with it. This happens with off the brush, sanded to 5000grit or polished up. whether coats are thick, thin or not brushed. I'm not really sure if this is the grain causing this like an optical effect or just something that plastic poly does? I will try shellac & lacquer one day to see.

Was this on the same timber (as per previous post in this thread http://www.woodworkforums.com/f9/cant-2pack-polyurethane-level-properly-207490) or something different? How fine did you sand prior and did you use any grain filler?

When I have used it on Teak, Meranti, and another unidentified furniture timber (that I think was poorly cut silky oak), I got the exact same result. It didn't matter how many coats, there was still evidence of grain. In each case it was wet sanded in between coats. I measured it (because I could at the time) and the depth averaged out at about 0.1mm after 3 coats. To be honest, on the pieces of furniture it doesn't bother me because there are no broad flat surfaces. On the meranti window sills it still irritates me when I clean them, but then 15 minutes later it has a layer of salt on it and I can't tell anymore.

On harder timber I haven't found it to be so much of an issue.

[SPF]

BTW thanks for posting up your results above.

[Tegmark]

Was this on the same timber (as per previous post in this thread http://www.woodworkforums.com/f9/cant-2pack-polyurethane-level-properly-207490) or something different? How fine did you sand prior and did you use any grain filler?

When I have used it on Teak, Meranti, and another unidentified furniture timber (that I think was poorly cut silky oak), I got the exact same result. It didn't matter how many coats, there was still evidence of grain. In each case it was wet sanded in between coats. I measured it (because I could at the time) and the depth averaged out at about 0.1mm after 3 coats. To be honest, on the pieces of furniture it doesn't bother me because there are no broad flat surfaces. On the meranti window sills it still irritates me when I clean them, but then 15 minutes later it has a layer of salt on it and I can't tell anymore.

On harder timber I haven't found it to be so much of an issue.

Hi SPF.

It was on all of my test pieces that are pine & tas oak. How obvious this is depends on how flat & glossy the top clear surface is. I sanded the raw wood with 180grit & some 240 & did not use any grain filler as at the time I was lazy as these were just small pieces & to me the grain of tas oak was too small & I thought to just fill them up with the clear. Maybe its the lack of grain filler that does this? I fill try this my self as I have never used grain filler.

On another old piece of generic hardware ply that has 6 thick coats of oil based polyu on it, it is extreme by comparison to these test pieces. It really looks like the surface is rippled at certain angles.

Thanks for your help.

[Tegmark]

Here is a long opening about 2mm deep that is see thru filled with poly.

https://s13.postimg.org/kiuahgrdf/woo_crack_clear.jpg (https://postimg.org/image/kiuahgrdf/)

At first I filled the crack up fully with a small fine brush, but afterwards much of the clear rises up out onto the surface, so it took me about 5 fills.
Then I sanded surrounding surface area with 80-120. Then finished off whole piece with 180 so opening is filled with clear flush to surface.
Then I added thin coat of clear just on the surface of crack with very fine brush. When staining whole piece the stain didn't take to the clear over opening & then I cleaned it up with alcohol on a fine pointy rag.
Later added 1st clear coat over whole piece later & built up coats.

Want to try this on some larger open knots but I think it will take ages as when clear is too thick it always has trapped air bubbles. I tried the epoxy on small openings, but it still makes fine air bubbles.



Here is why I only do very thick coats with 2pack.

https://s17.postimg.org/5fthed5u3/wood.jpg (https://postimg.org/image/5fthed5u3/)


Its just impossible for me to sand out pinholes without rubbing through on the edges, at very least the final coat would have to be very thick & the bulges/rises will show under the final coat.