Repel spots in water based lacquer?

[Kaisergrendel]

Hi all, I'm building a set of speakers with some Colortone WB lacquer from Stewmac. Before I actually touch the speakers I'm doing some sample boards. Having some weird problems with my 3rd one. I've asked a luthier's forum where I learned most of these finishing tips from but so far nobody's come up with an answer.

I sprayed my first neat coat of WB lacquer today on my 3rd sample board. Like the washcoats before, I'm getting small circular spots between 2-5mm in diameter in the coat where the lacquer has dried incredibly fast (or has shifted off the region.) while the rest of the coat is still wet.

After letting the first day's coats dry on my 3rd sample board the fast-drying spots have now become dimples in the finish. There's no particular pattern to the way the spots appear, they're just generally scattered across the surface. Here's what I did to the board previously:

1. Filled with turps-based grain filler. Sanded with stearate free paper.
2. Filled with Timbermate (water based filler). Sanded with stearate free paper.
3. Stained with spirit-based dye.
4. Lightly scuffed with synthetic abrasive pad.
5. Mixed WB lacquer with spirit-based dye, toned edges.
6. Sprayed 3 medium thickness coats of WB lacquer.

I have a feeling these are "repel spots," but I can't find much documentation about it. They're definitely not fisheyes as they're still in contact with the veneer, which in my mind rules out the turpentine in the grain filler rejecting the WB lacquer. Can anyone tell me what this is?

[tea lady]

:hmm: Water based laquor with spirit based dye? I wouldn't think they would mix. More like emulsify for a bit like salad dressing before separating again. Wouldn't you need to use water based dye? :shrug: The spots are prolly spots of spirit dye that then wont take water based on top! :think: That's what I reckon anyway.

[Kaisergrendel]

:hmm: Water based laquor with spirit based dye? I wouldn't think they would mix. More like emulsify for a bit like salad dressing before separating again. Wouldn't you need to use water based dye? :shrug: The spots are prolly spots of spirit dye that then wont take water based on top! :think: That's what I reckon anyway.

At first I thought that might be the case, but during toning the lacquer and dye were mixed together and quickly shot out atomized through a spray gun at a *very* low material setting, close to letting out no material at all. The droplets immediately flashed off on the veneer, so there was little chance of the emulsion breaking apart. The mixture was sprayed the heaviest on the edges of the board and almost never in the middle but there isn't an over-representation of the spots anywhere on the board - the pattern is random and regular. In addition, I rubbed in quite a heavy coat of spirit dye as the base color before the toning even started.

Now that I've tried to I remember the repel spots first appearing during the washcoats stages, before any of the dye even reached the board. I just didn't take note as they disappeared once the washcoats dried, probably because the coat was so thin. At this point it could either be contamination from the veneer backing glue, oil contamination from the spray gun, or the turps-based grain filler. Fairly sure I can eliminate timbermate as a problem.

[tea lady]

or the turps-based grain filler. Fairly sure I can eliminate timbermate as a problem.Could be. Maybe you could try a water based grain filler? Or a shellac grain filler? (Which is mello based . ) :shrug: :?

Why do you want to use water based laquor? Fume probs? I can't stand the smell either. But it dries really quickly, and part of how it works is that the next coat partially dissolves the last so it keys is. I would guess the water based one would not do that. It would just be another layer. :think: So any "resist spots" never get smoothed over no matter what you do. :C

[The Bleeder]

You say the "patern is random and regular"....... I'd be leaning to an oil/(may even be water) contamination.

What has the compressor hose be used for..... Check your water traps .. try a new hose....

Eliminate the compressor and it fitting first.

[Kaisergrendel]

Could be. Maybe you could try a water based grain filler? Or a shellac grain filler? (Which is mello based . ) :shrug: :?

Why do you want to use water based laquor? Fume probs? I can't stand the smell either. But it dries really quickly, and part of how it works is that the next coat partially dissolves the last so it keys is. I would guess the water based one would not do that. It would just be another layer. :think: So any "resist spots" never get smoothed over no matter what you do. :C

Timbermate is water based. I just whip it up with water and it's ready to be used to fill grain. I used a different grain filler *before* applying timbermate called Wattyl Grain Filler. It was a nasty thick goop that was a nightmare to sand off. It didn't even fill most of the holes, hence why I went back to Timbermate.

Mostly because my current spray booth would probably explode if I used nitro. I don't have the money or means to construct an explosion proof booth. I was looking around in Melbourne for nitro for months, and when I finally found it, I realized it just wasn't going to be safe enough for me to use.

I picked the WB lacquer I'm using because it's designed to mimic nitro in terms of workability. STEWMAC.COM : ColorTone Waterbase Lacquer (http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/ColorTone_Waterbase_Guitar_Lacquers/ColorTone_Waterbase_Lacquer.html)

It burns in, dries fast, and cures hard enough to buff to a mirror finish.


You say the "patern is random and regular"....... I'd be leaning to an oil/(may even be water) contamination.

What has the compressor hose be used for..... Check your water traps .. try a new hose....

Eliminate the compressor and it fitting first.

The entire compressor setup including the hose is relatively brand new and only has ever been used for either straight air gunning (cleaning) or spraying WB lacquer. There were no repel problems with my first two boards.

There's a filter at the mouth of the compressor, and another one attached directly to the gun itself. The one at the compressor works so well that the one under the gun never gets a single drop of condensation.

I'm going out to spray another few coats and see if the repel spots multiply (pointing towards a problem in the compressor rather than something that's on the board.) Will report back.

[Kaisergrendel]

Update: Sprayed 3 coats today. For the first 2 coats I thought I had it under control but the craters came back more and more with each coat. I submerge the spray gun nozzle in DA(metho) between coats to keep it wet. My suspicions are now focused on this.

The thing is before this I always primed the gun with metho before spraying the WB lacquer. It simply could be a case of high concentrations of unsprayed metho being left behind in the chamber and the nozzle.

[tea lady]

Pokig around on that site, they have this stuff called "fish eye flow out". Caused by silicon or other contamination. :shrug: Unfortunately that don't ship it outside the US! :C But I guess this sort of this is a common problem. It might give you a different term to google. :cool:

http://www.stewmac.com/catalog/images_1sm/0849_1sm.jpg

STEWMAC.COM : Details about Fisheye Flowout (http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/Fisheye_Flowout.html?tab=Details#details)

[tea lady]

Update: Sprayed 3 coats today. For the first 2 coats I thought I had it under control but the craters came back more and more with each coat. I submerge the spray gun nozzle in DA(metho) between coats to keep it wet. My suspicions are now focused on this.

The thing is before this I always primed the gun with metho before spraying the WB lacquer. It simply could be a case of high concentrations of unsprayed metho being left behind in the chamber and the nozzle.
Is that what they recommend? After a quick read I have a vague memory of them saying something about 50/50 mix of metho and water. :think: What about emailing the company? :shrug:

[ian]

Timbermate is water based. I just whip it up with water and it's ready to be used to fill grain. I used a different grain filler *before* applying timbermate called Wattyl Grain Filler. It was a nasty thick goop that was a nightmare to sand off. It didn't even fill most of the holes, hence why I went back to Timbermate.

Mostly because my current spray booth would probably explode if I used nitro. I don't have the money or means to construct an explosion proof booth. I was looking around in Melbourne for nitro for months, and when I finally found it, I realized it just wasn't going to be safe enough for me to use.

I picked the WB lacquer I'm using because it's designed to mimic nitro in terms of workability. STEWMAC.COM : ColorTone Waterbase Lacquer (http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/ColorTone_Waterbase_Guitar_Lacquers/ColorTone_Waterbase_Lacquer.html)

It burns in, dries fast, and cures hard enough to buff to a mirror finish.

The entire compressor setup including the hose is relatively brand new and only has ever been used for either straight air gunning (cleaning) or spraying WB lacquer. There were no repel problems with my first two boards.

There's a filter at the mouth of the compressor, and another one attached directly to the gun itself. The one at the compressor works so well that the one under the gun never gets a single drop of condensation.

I'm going out to spray another few coats and see if the repel spots multiply (pointing towards a problem in the compressor rather than something that's on the board.) Will report back.can you expand a bit on why you're using a grain filler?

I've successfully used the "thick goopy" Wattyl Grain Filler.
It's not intended for filling nail and screw holes.
It's a "true" grain filler that you're supposed to wipe on, let partially dry and then scrap the excess filler off the surface using a squeegee and/or coarse hessian and working across the grain. When dry it forms the base for a subsequent mirror finish. Other formulations of this sort of grain filler use talc and shellac.

BUT, if you have the gear to spray lacquer, you can use the lacquer as the grain filler
spray two coats, scuff sand, then spray two more, repeat till you can no longer see the pores — then start on your top coats.


your spot problem sounds like it's probably oil and water from the compressor — do you have a water / oil filter immediately before the line going to the gun?

[KJ401]

It sounds like silicone contamination. It could be from the turps based grain filler, could have been on the wood, might have been something on a rag you may have used at some stage to dust or wipe the timber; might even be something in the metho that shouldn't be there. If you own a diesel vehicle, it could even be particulants from the exhaust.

Using fish eye remover may well stop it happening again - and it is readily available here - try an autopaint supplier. BUT you have to deal with the craters, the spots of contamination you have. Fish eye remover will reduce the surface tension of the WB finish when its wet so it will flow out and over the silicone contamination, not around it as it is doing at the moment. If you want a flat finish, you'll have to cut back removing the craters.

Unfortunately you may have a couple of problems - you may spread the contamination as you sand. You may also find you cut through the coats of the WB finish, and end up with quite visible tidemarks.

To reduce the chance of spreading the contamination, wipe every face down with Prepsol ( or unleaded petrol). Then sand. Blow the dust off, and wipe everything down again with MEK (methyl ether ketone) - paintshops should have this. Read the ingredient label carefully to make sure it is only MEK.

Then respray - having added your fish eye remover to your finish. But before you use Fish Eye remover, make sure it is OK to use it in the WB finish you are using. It can cause far worse problems than the one you are trying to solve. Be very very sure you put a good dose of MEK through your gun after using any finish with Fish Eye remover in it.

And nitro is not so volatile that I wouldn't use it without an explosion proof booth. If you've got exposed fan motors in a confined space I might worry but it's the dry overspray dust that is actually the issue - and it can be for any solvent based finish if the overspray dust is allowed to collect and is ignited somehow. WB finishes are a lot fussier as are 2 pack - you may not be able to work out where the contamination is coming from. It may never happen again. You may not be able to sort it out. If that happens, reconsider nitro or precat.

And as for ending up with tidemarks when sanding back through the coats with WB finishes? No easy answer there, though the use of piratical and colourful language vaguely helps.

[KJ401]

Sorry - forgot to address the compressor / gun issue. Don't assume your filter is trapping everything you want it to trap - if it's a water filter, it wont necessarily be doing the job you expect with oil. Filters aint filters. The filter that came with your compressor may deliberately allow oil through the lines - it's how air tools are lubricated.

Check what type of filter you actually have - check the cartridge inside it. I'd visit the autopaint shop and buy a reasonable quality water AND oil filter and add it to my air line about half way between the compressor and the gun. Also helps if you loop your airline up from the compressor, then get it to dip - put the new filter on that dip - and then loop it back up to your gun.

If you have got oil in your lines - replace them before you put the new filter in place. Also wash your gun out with MEK a few times, strip it apart and soak everything in MEK overnight. Be careful though with any nylon or neopryene washers - they can dissolve.

[Kaisergrendel]

Pokig around on that site, they have this stuff called "fish eye flow out". Caused by silicon or other contamination. :shrug: Unfortunately that don't ship it outside the US! :C But I guess this sort of this is a common problem. It might give you a different term to google. :cool:

http://www.stewmac.com/catalog/images_1sm/0849_1sm.jpg

STEWMAC.COM : Details about Fisheye Flowout (http://www.stewmac.com/shop/Finishing_supplies/Finishes_and_solvents/Fisheye_Flowout.html?tab=Details#details)

I can think of a locally available flow assisting additive called Floetrol, which could yield similar results. Might try that if I keep having this problem.


can you expand a bit on why you're using a grain filler?

I've successfully used the "thick goopy" Wattyl Grain Filler.
It's not intended for filling nail and screw holes.
It's a "true" grain filler that you're supposed to wipe on, let partially dry and then scrap the excess filler off the surface using a squeegee and/or coarse hessian and working across the grain. When dry it forms the base for a subsequent mirror finish. Other formulations of this sort of grain filler use talc and shellac.

BUT, if you have the gear to spray lacquer, you can use the lacquer as the grain filler
spray two coats, scuff sand, then spray two more, repeat till you can no longer see the pores — then start on your top coats.


your spot problem sounds like it's probably oil and water from the compressor — do you have a water / oil filter immediately before the line going to the gun?

Yeah, I made the mistake of leaving too much on the surface. When I tried to sand it it quickly gummed up on my discs, ruining them. I don't intend to continue using it as it's just really asking for trouble mixing it with WB lacquer.

I might try using the lacquer as a filler. The only problem is it's pretty wasteful to do it, and it costs dearly to ship more of it from the US. At the moment I'm actually quite happy with Timbermate, which is water based to boot.

There's a filter at the compressor and another filter immediately before the gun. The one near the compressor does all the work - the one near the gun is always bone dry.


Is that what they recommend? After a quick read I have a vague memory of them saying something about 50/50 mix of metho and water. :think: What about emailing the company? :shrug:

I think I remember reading somewhere to prime with metho first, then water. Can you remember where you saw this tip?

I've fired off an email to Stewmac, will see what they say.

(Not quoting as this post is long enough) KJ401: That's quite a bit to absorb! The first thing I'll try is flushing the gun with water after priming with metho. The worst case of cratering I got was after I made the mistake of spraying even when the nozzile was dripping metho. I somewhat recreated this by brushing the WB lacquer onto some scrap wood, then dripping some metho on it - it definitely repels the lacquer, but eventually dissolves into it and the coat almost flows out evenly after. My hope is that this is what happens albeit with a slightly different behaviour when I spray with a nozzle wet with metho.

As I mentioned earlier in this post, I might try a flow assist additive in place of a true fish eye eliminator as it is virtually impossible to source it in Melbourne.

I probably won't find prepsol, but possibly an equivalent. If I do fall back to unleaded petrol, how can I be sure the additives in the fuel don't cause even more problems?

My booth is about 4x4', reasonably confined, and my fan is just a domestic box fan forced into spray booth service. Add to that the fact that I use a 300W halogen inside the booth for illumination, and I don't think anyone in their right mind would attempt to spray anything combustible inside.

The filters are called "moisture filters" and didn't come with the compressor. The one I attacked to the compressor doubles as a regulator and collects a yellowish, watery+greasy liquid. This is why I think it's doing its job as far as filtering water and oil is concerned.

Addendum: I think I forgot to clarify one very important thing. These "craters" or "repel spots" aren't places where the lacquer doesn't adhere to at all - rather the lacquer THINS OUT and coats the crater thinly while the majority of the lacquer pools around the craters. The lacquer DOES flow over these spots, just at the regular thickness.

[tea lady]

You haven't got any pics? No one with a macro camera near by? :think:

If you are worried about the booth, you are near enough to Knox Woodworkers who are setting up a spray Booth for spraying NC laquor at the moment. Maybe you could join there to use the facilities? :shrug: (I am a member, but the rest of the members are OK!.:cool: )

[Kaisergrendel]

You haven't got any pics? No one with a macro camera near by? :think:

If you are worried about the booth, you are near enough to Knox Woodworkers who are setting up a spray Booth for spraying NC laquor at the moment. Maybe you could join there to use the facilities? :shrug: (I am a member, but the rest of the members are OK!.:cool: )

Now that you mentioned it, I wonder I didn't do take a picture!

Interesting, do you get to keep your work there between coats?

[tea lady]

Now that you mentioned it, I wonder I didn't do take a picture!

Interesting, do you get to keep your work there between coats?Prolly not, But CA laquor dries really quickly. So its not sitting round for ages gathering dust. :doh: You'd be able to do it nearly all in one day. :shrug:

[Kaisergrendel]

I've never heard of CA lacquer before. Can you tell me what it is?

[tea lady]

I've never heard of CA lacquer before. Can you tell me what it is?:doh: Meant NC. :rolleyes: Stupid brain. :C

[ian]

Thanks for that Kaiser, but I'm still confused as to what you're trying to do with the filler.

I think of Timbermate as a filler for nail and screw holes and other blemishes, not as a grain filler where you want to fill the surface but not obscure the grain.

Even though the Wattyl stuff is oil based, a coat of shelac will seal the surface allowing the use of water based top coats.

[Kaisergrendel]

:doh: Meant NC. :rolleyes: Stupid brain. :C

Hahah ok. I have to at least try everything to make it work with WB lacquer, otherwise I'll be wasting a whole gallon can of very expensive stuff. Will keep the club in mind.


Thanks for that Kaiser, but I'm still confused as to what you're trying to do with the filler.

I think of Timbermate as a filler for nail and screw holes and other blemishes, not as a grain filler where you want to fill the surface but not obscure the grain.

Even though the Wattyl stuff is oil based, a coat of shelac will seal the surface allowing the use of water based top coats.

I bought a can of the Wattyl stuff from my local Bunnings Warehouse and found a thick layer of dried varnish/goop sitting on top of the filler. After I removed this it took me a good bit of elbow grease to whip the stuff back into an even emulsion. Not sure if this means it was expired, but I'm not keen on using it again just yet. After trying to sand off the excess I was met with open grain again, either from over-sanding or the filler not working properly, so I followed up with Timbermate.

Actually Timbermate can be used as a grain filler - you just mix it with water to the consistency of thick cream then wipe it on as you would a "true" grain filler. This is what I did and It works for me, and it's virtually guaranteed not to cause problems with WB topcoats.

Update: Just sprayed another 3 coats today, taking care to flush the metho from the gun with distilled water before each coat. The repel spots are *still* coming back.

Diagnosed a problem with the gun; the nozzle cap was backfiring air. It could be the reason my gun's been sputtering lately. I patched the thread up with some sealing tape, and it seems to be spraying water smoothly now, though I haven't tested it with lacquer. Also cleaned every part of the gun's material channel. The diminished flow could account for residual metho being left inside the chamber and sputtering out with the lacquer, causing a regular, random pattern.

Might try wiping down the board and soaking the gun's parts in MEK next time. Currently I always wipe down the board with a 50/50 mixture of water and metho before starting the day's coats, but it doesn't seem to help.

[KJ401]

Still sounds like silicon contamination; and I'd be pretty doubtful it's the metho causing the problem. If you've got greasy water trapping in the filter/regulator, I wouldn't be certain it is catching it all. Also, how often do you drain your receiver tank? You should be doing it daily, before you start up the compressor.

Re prepsol versus petrol. Ordinary unleaded, not 10% ethanol, shouldn't cause you any problems. It is horrible to work with though - prepsol is stinky but better than petrol. Prepsol is readily available from autopaint suppliers - google lists 9 in Melbourne.You should also be able to get fish eye remover from them.

Or try this mob in Glenroy:

AALL-PAINTS (http://www.aallpaints.com.au/shop/index.php?cPath=24&osCsid=206fad60be8134a4fa79bd0ced733016)

But check first with the WB finish manufacturer whether adding fish eye remover is not going to cause more problems - some WBs are modified urethanes and they require a particular solvent mix to get around this problem. Or complete removal and refinishing - if it comes to that, I'd be giving all surfaces a couple of sealer coats of dewaxed bleached shellac.

[Kaisergrendel]

I drain it nearly every day and never get more than 3-5ml of condensation.

Surprise! Sprayed a coat just now and there wasn't a single repel spot in sight. I went back to using a specially formulated retarder that I bought with the lacquer. Thought it might help level and flow the lacquer better, which it did! Will spray the rest of the day's coats and see if the effect holds. If it does, it saves me the trouble of getting prepsol and all manner of additional solvents.

One thing I overlooked was that I used the retarder on my second sample board (I'm working on the third one now) and never had the sputtering or repelling problems as I am now.

[Kaisergrendel]

Spoke too soon, the repel spots came back with a vengeance on the second coat and then even more on the third coat.

This is a consistent pattern now. The day's first coat is always relatively even, with repel spots appearing with greater frequency with every coat I apply. Is this consistent with silicone contamination, or oil?

Edit: A thought just occured to me - I used baking paper to protect the iron as it went over the veneer as per its instructions. Could this cause any problems?

[tea lady]

Edit: A thought just occured to me - I used baking paper to product the iron as it went over the veneer as per its instructions. Could this cause any problems?:think: Maybe. You could try aluminum foil on the iron instead. :shrug: But if more and more spots are coming with each layer it is prolly something to do with the spray gun. :shrug:

[Kaisergrendel]

:think: Maybe. You could try aluminum foil on the iron instead. :shrug: But if more and more spots are coming with each layer it is prolly something to do with the spray gun. :shrug:

That's exactly what I thought, I'm just wondering if silicone contamination works in a counter-intuitive way eg. it continuously floats up to the surface with every coat sprayed.

[tea lady]

That's exactly what I thought, I'm just wondering if silicone contamination works in a counter-intuitive way eg. it continuously floats up to the surface with every coat sprayed.Dunno! If it is resisting I guess it just keeps resisting. Wonder if a bit of detergent would break the surface tension enough to make it flow out? :think:

[Kaisergrendel]

It'll probably come out of my spray gun in a foam to begin with!

[tea lady]

It'll probably come out of my spray gun in a foam to begin with!:doh: Oh yeah! :rolleyes: What about glyserine then! :shrug:

[tea lady]

Rather stupid question I guess, but what are you wiping the piece down with after sanding, but before spraying? Old t-shirts from the wife's chest of draws? (What is in fabric softener? :think: or the soap powder? :shrug: )

[Kaisergrendel]

Disposable dry wipes from a sealed pack, soaked in 50/50 solution of metho and distilled water.I highly doubt there'd be a problem here.

[ian]

Spoke too soon, the repel spots came back with a vengeance on the second coat and then even more on the third coat.

This is a consistent pattern now. The day's first coat is always relatively even, with repel spots appearing with greater frequency with every coat I apply. Is this consistent with silicone contamination, or oil?

Edit: A thought just occured to me - I used baking paper to protect the iron as it went over the veneer as per its instructions. Could this cause any problems?what you describe sounds a lot like oil contamination, starting with a clean gun, the more you spray the worse it gets.
Everything I've heard about silicon contamination, says that it starts off bad and stays that as bad as you spray extra coats.

my suggestion is
replace the water filter at the compressor
clean the air hose
install an oil trap filter immediately before gun (or install a new filter membrane in your existing filter)
run new air hose between the final oil filter and the gun

see what happens when you
1) spray on your test board and
2) spray onto a board that has only been sanded -- i.e. no veneer, no iron, no stain, no filler, etc -- if you get spots, the problem is definitely related to gun, the material and the air supply


at this point it might be worth while revisiting one of your other posts ...
So I spent a significant amount of money on a set of speaker kits. I got a little bit excited.

Got some oak veneer, an air compressor, gravity fed spray gun, moisture trap, steel wool, pumice, built myself a spray booth, some Haymes Aqualac, only to find out that nobody seems to recommend spraying my finish of choice - water based Acrylic Lacquer.

I've checked all the usual brands - feast Watson, Wattyl, Cabots, even Haymes. None of them specify spray gun as a possible application method on their WB acrylic lacquer tins. Asking a shop assistant got me basically "it's because of the way it goes on, it's just better with a brush." which doesn't really help.

Can anyone please shed some light on this? I've been going back and forth between varnish, 2 packs, polyurethanes and lacquers for weeks! The sheer lack of consensus on which terms mean what is bewildering.

Thanks in advance!

ps: I've been working with wood as a light hobby for about 14 years so you don't have to start from scratch when explaining things.given this, do you still get spots if you apply the finish with a brush ?

[Kaisergrendel]

what you describe sounds a lot like oil contamination, starting with a clean gun, the more you spray the worse it gets.
Everything I've heard about silicon contamination, says that it starts off bad and stays that as bad as you spray extra coats.

I see!



my suggestion is
replace the water filter at the compressor
clean the air hose
install an oil trap filter immediately before gun (or install a new filter membrane in your existing filter)
run new air hose between the final oil filter and the gun

The thing that's puzzling me the most is the fact this whatever's contaminating the finish is actually *soluble* in my water based lacquer. I'm not getting fisheyes or adhesion problems even with the moderately heavy sanding I do with every coat to level out the craters. First thing I'm going to do is extract some of the filtered goop from the regulator and see if it mixes with the lacquer. If it doesn't, I can probably rule out oil contamination right there.

I can try replacing the hose but the regulator is a bit out of my means to replace at the moment. The filter under my gun never traps anything so I will have to source different one from elsewhere. Also the entire system is close to brand new with only about 2 months worth of sporadic use.



see what happens when you
1) spray on your test board and
2) spray onto a board that has only been sanded -- i.e. no veneer, no iron, no stain, no filler, etc -- if you get spots, the problem is definitely related to gun, the material and the air supply

I'm testing on some pine offcuts at the moment. I spray on the pine first, then spray on the test board, so it's the same batch of air/lacquer. The pine is extremely absorbent so it will be some days before I can reproduce the problem. (The repel spots aren't visible until there's a glossy coat on the surface)



at this point it might be worth while revisiting one of your other posts ... given this, do you still get spots if you apply the finish with a brush ?

After that post I gave up on the aforementioned Haymes aqualac as it was near impossible to get a good even coat by spraying. I'm now using Stewmac's Colortone WB Lacquer, which is meant to be sprayed, not brushed.

[tea lady]

After that post I gave up on the aforementioned Haymes aqualac as it was near impossible to get a good even coat by spraying. I'm now using Stewmac's Colortone WB Lacquer, which is meant to be sprayed, not brushed.I was gonna suggest trying just applying it with a brush. Just as a test. We know it is meant to be sprayed, but if you eliminate the gun you can see if its actually in the lacquer.:cool:

[Kaisergrendel]

At first I thought it was a great idea until I noticed the way it goes onto the board. When sprayed, the lacquer is misted on, allowing the contaminant to stay in one spot and work its magic. When it's brushed, any potential surface contamination is smeared across the surface and possibly diluted till it's too weak to have any effect, particularly since the contaminant is actually soluble in the lacquer.

Wiped on two coats of lacquer no cratering. Regardless of the previous paragraph, I'm starting to believe it actually has to do with my air supply.

[tea lady]

At first I thought it was a great idea until I noticed the way it goes onto the board. When sprayed, the lacquer is misted on, allowing the contaminant to stay in one spot and work its magic. When it's brushed, any potential surface contamination is smeared across the surface and possibly diluted till it's too weak to have any effect, particularly since the contaminant is actually soluble in the lacquer.

Wiped on two coats of lacquer no cratering. Regardless of the previous paragraph, I'm starting to believe it actually has to do with my air supply.The plot thickens. You'll be the water based lacquor expert after this. :rolleyes:

[Kaisergrendel]

The plot thickens. You'll be the water based lacquor expert after this. :rolleyes:

Ha, I imagine I will be!

[Kaisergrendel]

Okay, I'm on the lookout for new air filters. These are what I have at the moment (not exact model/brand but you get the point)

At the compressor:
http://www.tme.eu/katalog_pics/0/3/7/037dc6de026b9f1ae5e8e1a060ddd89d/b73g-3gk-qt3.jpg
Below the gun:
Water Separator - In Stock at www.ozintersales.com.au (http://www.ozintersales.com.au/Water-Separator_pA56DE4E3-C20D-46CE-B2D6-4C90CB96B8CC.html)

I think I've come to the rude realization that, while these seemed expensive to me when I bought them, they're about cheapest, crappiest filters I can buy with money.

Took a look at this page:

Filters / Regulators / Gauges - In Stock at www.ozintersales.com.au (http://www.ozintersales.com.au/Filters--Regulators--Gauges_c4EB1F5AF-737D-4775-A54E-5FB1EBBEBE97)

And ignoring the multi-hundred or thousand dollar filters, which I simply can't justify buying, (I'd rather switch to brushing) I'm looking at the next cheapest filter:

AMAXI Air Filter - In Stock at www.ozintersales.com.au (http://www.ozintersales.com.au/AMAXI-Air-Filter_pE0434EF2-B23D-47BD-A460-B3733484D8CB.html)

Anyone have any experience with this type of filter?

[The Bleeder]

Back again.

What type of compressor have you got. I've sprayed a lot of products and it comes back to the compressor, the medium, both of which you look for contamination and then finally the surface.

If the surface takes it (undiluted) by brush in thin (and I mean thin) coats then start looking at the other two.

Just because a compressor is new doesn't mean you won't have an oil contanimation issue. (This is what I think it may be).

The compressor I use is a twin cylinder ~130lpm FAD. Filters get changed reguarly. Used for a lot of things including nail guns and impact drivers. Separate hoses for these to the spray gun.

What hose are you running? This can also be a source ...just because it's new it may have already been contaminated.

Only suggestion I can make is find someone else that has a spray kit and see if they get the same result. If they don't then sorry but it's your system.

[Kaisergrendel]

Hey bleeder, I've tested on a piece of raw wood and reproduced the same problem, so definitely looking at oil contamination now. Checking the exit port of the regulator/filter shows that it definitely isn't filtering all the moisture out as I can see droplets of oil/water.

I've bought a new, different hose. Added a drip tap at compressor and moved the regulator/filter to near the end of the line.

My compressor is rated at 2.5hp 75lpm. No specification on the number of cylinders but it sounds like there's 2 of them to me. It only starts up every 2-3 coats because the sample board is so small.

Can you recommend a good affordable filter to me? preferably below $100 and not over $200.

One thing I noticed - I never thought much of it but I recently did an oil change because the compressor was started to sound noisier. I filled up the oil chamber till the oil was near the top of the target ring. The manual says to "fill the crank case until the oil reaches the red mark on the sigh glass." Since the "red mark" is a circle, it's a little ambiguous as to whether the oil level should be below, in the middle, or touching the top of the circle. Check the attached picture to see how it looks now.

I sprayed about 12 coats on my first sample board and 20 coats on my second sample board and *never* had this problem. I have a feeling my compressor is overloaded with oil and leaking it into the air.

General update: I found "prep wash" which the shop assistant told me is "the same thing" as prepsol. Indicated for removing silicone, wax and grease. Smells suspiciously like turpentine. Immediately after wiping down the board with it, twice, cratering has decreased, but not been eliminated. Not sure if this is just a coincidence. I stupidly used a heat gun to make sure the wash was completely evaporated before spraying lacquer, but the iron-on veneer came right back and bit me in the ass. I have steaks of delamination going on with grain protruding upwards from the substrate. The re-melting glue probably released water vapor and warped the veneer.

I sanded through an edge and two more corners this time while doing leveling. The cratering is probably making it far more difficult than it should be, but do you guys have any tips for levelling a finish without touching timber underneath?

[Kaisergrendel]

More questions:

1. Do you generally need to use brass/steel pipes in order for the drip taps to work? I'm using plastic ones at the moment.

2. How often do you need to exhaust the air tank? (I like the idea of leaving the air in for 1-2 days until the next time I need it, instead of starting from scratch.)

3. Is there any danger in fully opening the stop valve on the compressor to exhaust the air? (Explosive decompression?)

[The Bleeder]

Hi,

The oil level looks to be a bit on the high side. I keep mine at about the middle of the circle.

When using the compressor I tend to bleed the tank and empty any water that has accumulated every 2 days. If I'm not going to be using it after one session then I'll do it there and then.

Can you post a pic of you setup. All of my water and oil filters are at the compressor. I use different hoses for spraying to those that are used for other devices.

To empty the compressor I usually have some cleaing up to do so out with the air gun and once all the air is gone I'll open the valve and empty everything.

Now this might sound a bit on the bad side but....since I think you have overfilled it a full strip down and clean may have to happen.

[Kaisergrendel]

Hi,
Can you post a pic of you setup. All of my water and oil filters are at the compressor. I use different hoses for spraying to those that are used for other devices.

Yup, the pics are attached. First shot is the compressor with the hose hang straight up from the ceiling, directly outside the spray tent. Second is the drip tap, third is the hose coming back down and into a regulator. The coiled hose is the one I previously used. I'm in the process of reconfiguring it so it might seem a bit messy.



To empty the compressor I usually have some cleaing up to do so out with the air gun and once all the air is gone I'll open the valve and empty everything.

So you blow everything out through your spray gun? If so, that's what I do to, but I never have enough to clean so I find myself standing there for a few minutes holding the trigger down till it's fully depressurized.



Now this might sound a bit on the bad side but....since I think you have overfilled it a full strip down and clean may have to happen.

You mean take it apart and clean it out? Gosh, I may have to buy an entirely new one! I'll try draining some of the oil first and reconfiguring the air line before it comes to either of those options.

[The Bleeder]

Ok, from what I can see you need to get the water trap and primary oil filter at the outlet from the compressor. Then you can have a secondary where ever you like if you need it. Try looking in evilbay for an oil filter you might get lucky.

Yes I wash out the gun then spray it at everything outside, till the tank is basically empty (young son likes to take on the lizards with it).

Yes drain some of the oil and try to get it around the middle of the cricle (if it's a bit low in the circle that's not a prob). It depends on how much you have used it with it being overfilled, a primary and secondary oil filter might work untill most of the oil that has entered the tank etc.. has been disapated. (It's a bugger of job to strip and clean and rebuild them).

[Kaisergrendel]

Ok, from what I can see you need to get the water trap and primary oil filter at the outlet from the compressor. Then you can have a secondary where ever you like if you need it. Try looking in evilbay for an oil filter you might get lucky.

Thanks, I am looking for a filter to stick onto the compressor outlet, but I haven't been able to any besides the ones I can find from Bunnings or evilbay besides the ones I have. What kind of filters do you use?

Also, will using metal piping attract more condensation for the drip tap?



Yes I wash out the gun then spray it at everything outside, till the tank is basically empty (young son likes to take on the lizards with it).

I see, I guess I might stick to rubberbanding the air gun.



Yes drain some of the oil and try to get it around the middle of the cricle (if it's a bit low in the circle that's not a prob). It depends on how much you have used it with it being overfilled, a primary and secondary oil filter might work untill most of the oil that has entered the tank etc.. has been disapated. (It's a bugger of job to strip and clean and rebuild them).

I've used it about 10-15 cycles. (number of times it's started and stopped) Fingers crossed the tank is still reasonably clean. How hard would it be to disconnect the receiver tank and flush it with some kind of degreaser?

[ian]

How's the spray finishing going ??

[Kaisergrendel]

Hey sorry, I should be updating but nothing much has happened. I've bought from ebay a vehicular compressed natural gas filter to use in my compressed air setup. It's a bit of a wild card but if it saves me from spending $200 bucks for the next filter up I'll be more than happy. Still waiting for that to arrive.

I've also bought some shellac flakes and mixed half of it to use as my washcoats. Can't wait to put it all together.