Grain filling

[cjbfisher]

I have finished a few benchtops at work lately, and I haven't been happy with the results that I have achieved. First was some laminated Melunak tops, and today it was laminated New Guinea Rosewood. Both times, the process has been 2 coats of Feast Watson sanding sealer, sanded back with 240 grit, followed by two/three coats of poly rubbed back with 0000 steel wool between coats. Oil based for the Melunak, and water based for the Rosewood.
I don't have a lot of experience with finishing, and I've done things this way because that's what I've been told to do. I have done this before on Blackbutt, and was quite happy with the result, but the more open grain of the latest two timbers is causing me grief. How do I go about filling the grain so that the poly doesn't suck down into the surface? The sanding sealer is supposed to have some grain filling properties, but obviously not good enough.

[FenceFurniture]

I have been doing some extensive experimenting with this just recently. One or two others have followed a similar procedure and have been as happy as I am with the results. One or two others may disagree violently with my methods, but may also have never tried them (that's just a bit of a caveat). Also, bear in mind that it depends upon the particular timber, it's colour and how it responds.

Furthermore, I am hopeless at following instructions that say "stop sanding at 240 grit". For me that it utter bollocks, and anyone who subscribes to it has never seen what happens to the grain of great (Australian hardwood) timber from grits 500 through to 4000. This is not about smoothness (although that is quite literally SENSATIONAL!) but rathermore what happens to the grain visually as each finer grit is stepped up. It's a bit like trying to convince a virgin how good *certain activities* can be....

So, before I get to the technique, this is what you can achieve with sanding to (in this case "only" 3000) with no finish applied - bare wood.



Note that I have focussed the camera on the reflections rather than the timber grain. You can very clearly see the reflection of the alum extension table of my thicknesser on the left side, and the green locking handle (et al) of my Kapex mitre saw on the right. In the middle is the reflection of the light source itself. Remember - no finish applied yet - just sanding.

So that was an experiment to show what can be achieved with just sanding. What I actually do these days is sand to (probably) 500, and then do two coats of sanding sealer (ensuring that I sand each one back to bare timber). This naps up the grain which can then be sanded off. At $40 per litre for Feast Watson SS - yer boss is wasting his dough badly. I get some expired liquid shellac ( in this case Forum Owner Dewaxed White Shellac) and dilute it to about 8:1 with ordinary meths (i.e. not hell expensive and difficult to source Industrial Meths). It actually recommends this on the Shellac bottle when it is out of date.

I have compared this to the hell expensive FW "specific" SS and it is just as good....if not better because it dries in either seconds or minutes as opposed to 45(?) minutes for FW SS. Oh yeah, and it's kinda free because the shellac was "useless" and meths cost bugger all.

So 2 coats of that, sanded back to bare timber - 10 minutes depending on job size of course - and now you are ready to apply the next step, which is grain filler.

You can use some pigmented things like Timbermate (not for me....) or Intergrain filler, but the smoothest one I have used is AquaCoat (NOT AquaCote or BoatCote). The first time I used AquaCoat is well documented in this thread:
https://www.woodworkforums.com/f187/b.../2#post2071342

A pic from that thread:


I cannot take credit for the beautiful timber, but I will take credit for making the most of it....... but with good products.

It is crazy easy to use. Rub it in like paste wax, sand it off - repeat only if necessary, dependent upon timber and how open the grain is. In my opinion it does not work well on blonde timbers, as it showed up dark in the tests that I did on some very very curly Blackbutt (but I may have overworked it rubbing it in).

The smoothness is FANTASTIC!

After that, apply whatever finish the job requires.

AquaCoat is available from Australia's only supplier, and you'll be chuffed to learn he is in Brisbane.
https://armstronglutherie.com.au/products/

I used a tiny amount for that 1500x900 table (it is documented in the thread, but from memory I think <100ml?)


You may also get some benefit from these threads:
https://www.woodworkforums.com/f9/osm...playing-221673
and particularly this one by qwertyu
https://www.woodworkforums.com/f9/grain-fillers-221802

[yvan]

So, grain filler is not the same as sanding filler?

[woodPixel]

FenceFurnitures summation is spot on.

If you don't have AquaCoat, use two or three light costs of shellac, then spray down 6 wet coats of polyurethane, then wet sand it perfectly flat, then polish (Google "rubbing out")

If time isn't on your side and you can't wait for the poly to harden, use nitrocellulose or Mirotone Mirolac 3220. Epoxy also works brilliantly.

Shiney!

[FenceFurniture]

So, grain filler is not the same as sanding filler?

To be honest I'm not knowledgeable enough to say categorically. I can only say what I have found gives an excellent result. As far as I'm concerned, and I'll stand corrected, sanding sealer is to raise up the remaining fibres so they can be knocked off when sanded back again. You can certainly feel the surface has become rough after the SS is applied. If this isn't done then the next wet thing that goes onto the timber will raise up the grain - if that is the finish itself which is not going to be sanded back at all then you will have a permanently rough surface.

Grain filler is to fill the pores in the timber, and so different timbers will have different requirements, depending on how open the grain is of that species. Australian Red Cedar is very open grained and will probably need two applications of AquaCoat, maybe even three in parts. OTOH, Gidgee would only need one. Certainly grain fillers like TimberMate and Intergrain won;t raise up the grain because they are super viscous with almost nil moisture content.

I suppose that the SS step could possibly be deleted when using AquaCoat, given that the AC is wet and would raise up the grain. I am just loath to change a process that is giving me the results I want - and I enjoy finishing, unlike some who find it a chore. Watching the grain pop out when using each grit past 500 is really rewarding.

Another point - I do not subscribe to the view that sanding up to very fine grits just burnishes the timber so that the finish cannot penetrate the timber. Timber is porous and will still absorb oils. Other finishes like Shellac, varnishes et al tend to sit on top of the timber anyway, so what's the difference?

[Cliff Rogers]

Also worth a look for clear grain filling is Pacer Z-POXY EPOXY Finishing Resin PT40 ZAP.
You'll find it on eBay.
https://www.ebay.com.au/sch/i.html?_...0+ZAP&_sacat=0

You'll find demos on youtube.
https://www.youtube.com/results?sear...sin+grain+fill

[woodPixel]

If you are super skint, you can use egg white.

It acts as both. Luthiers have been using... Forever

[cjbfisher]

Thanks for the replies. Looks like I have a lot of learning to do. Are there any good books out there that you would recommend for learning about the different types of finishes and where/how to use them.

[woodPixel]

You know, there are many very talented woodworkers here and a lot of good threads on finishing.

I honestly think the VERY best finishes and detail work are completed by Luthiers, especially acoustic guitars. Their finishing, attention to extreme detail and inlays are astonishing.

[ian]

I have finished a few benchtops at work lately, and I haven't been happy with the results that I have achieved. First was some laminated Melunak tops, and today it was laminated New Guinea Rosewood. Both times, the process has been 2 coats of Feast Watson sanding sealer, sanded back with 240 grit, followed by two/three coats of poly rubbed back with 0000 steel wool between coats. Oil based for the Melunak, and water based for the Rosewood.
I don't have a lot of experience with finishing, and I've done things this way because that's what I've been told to do. I have done this before on Blackbutt, and was quite happy with the result, but the more open grain of the latest two timbers is causing me grief. How do I go about filling the grain so that the poly doesn't suck down into the surface? The sanding sealer is supposed to have some grain filling properties, but obviously not good enough.

Hi cjb
first you need to recognise that the three timbers you mention -- Melunak, NG Rosewood, Blackbutt -- are very different in terms of how open their grain is.

A sanding sealer will do some limited grain filling on close pored timber like Blackbutt, but on open grain woods like NG Rosewood there is just not enough "filler" in the mix to fill the grain.
Your options are to use multiple coats of finish -- you keep applying until the pores are full -- with a traditional shellac finish you added talc to the mix to achieve -- after several days -- a piano finish.

The other alternative is to use a grain filler like that made by Wattyl. Wattyl Craftsman Grain Filler


As to books, etc.
Almost anything by Bob Flexner https://www.amazon.com/Bob-Flexner/e/B000APORGS
https://www.popularwoodworking.com/w...inishing-blog/

[rustynail]

To be honest I'm not knowledgeable enough to say categorically. I can only say what I have found gives an excellent result. As far as I'm concerned, and I'll stand corrected, sanding sealer is to raise up the remaining fibres so they can be knocked off when sanded back again. You can certainly feel the surface has become rough after the SS is applied. If this isn't done then the next wet thing that goes onto the timber will raise up the grain - if that is the finish itself which is not going to be sanded back at all then you will have a permanently rough surface.

Grain filler is to fill the pores in the timber, and so different timbers will have different requirements, depending on how open the grain is of that species. Australian Red Cedar is very open grained and will probably need two applications of AquaCoat, maybe even three in parts. OTOH, Gidgee would only need one. Certainly grain fillers like TimberMate and Intergrain won;t raise up the grain because they are super viscous with almost nil moisture content.

I suppose that the SS step could possibly be deleted when using AquaCoat, given that the AC is wet and would raise up the grain. I am just loath to change a process that is giving me the results I want - and I enjoy finishing, unlike some who find it a chore. Watching the grain pop out when using each grit past 500 is really rewarding.

Another point - I do not subscribe to the view that sanding up to very fine grits just burnishes the timber so that the finish cannot penetrate the timber. Timber is porous and will still absorb oils. Other finishes like Shellac, varnishes et al tend to sit on top of the timber anyway, so what's the difference?

Oil requires a much finer sanding than either poly or lacquer. Both the later are surface finishes and require a key to keep them in contact with the timber. Time is the teacher here. After a while, the poly is inclined to lift from over-smooth surfaces, particularly if the surface is concave, as in a moulded table edge. Without a key, this degradation manifests much earlier. And with poly, it now has to be stripped right back before recoat.
An oil finish can be slurry sanded on the first coats to give an effective grain fill. This method can be repeated until the surface has reached a suitable level of fill which will vary specie to specie. With lacquer, the surface can be "pulled" to minimise grain indentation. This method is used to avoid the overmasking of the grain feature when fillers are used. A beautiful piece of flame or fiddleback timber needs to have s*#t rubbed into it like a hole in the head. Poly is a great name for a cocky but not nice to wood.

[woodPixel]

I'm not so sure that all poly is crap. Some of the vendors I've been speaking with recently have some seriously amazing formulations. I'm obviously not talking about Bunnings discount stuff, but Behlans, Intergrain, Norglass and Bondall....plus my personal favourite Mirotone.

Luthiers that I talk with, who sell $5-$8000 acoustic guitars use Mirotone and Behlans. They swear by it.

Given these blokes are the absolute undisputed rockstars of finishing, they are worth looking in to.

I'll dig up some links and pictures

[rustynail]

I agree, they do come up a treat. Refinishing is where things start to come unstuck (literally).

[Robson Valley]

What's the value in constantly shredding the wood surface with sandpapers?

Try cutting the wood for a genuine smooth surface with cabinet scrapers.
You can make your own out of scrap steel with a chalked up file.
I've got dozens, they are so cheap and simple to make.
Sandpapers are for sharpening.

[auscab]

A good way of going in the right direction with grain fill that I like is .
Make a pva / water soloution . About 15% pva. Sand the surface with something like a 320 grit paper around in circles across the grain in a slurry. Its got to be watched closely that its not to wet . That just washes the slurry out of the grain if it is . To dry and you start skidding over slurry dry build up . Just right and you see a full grain fill happen in front of your eyes . let it dry and the glue sets it off. When you touch it next your not wiping dust out of the grain. If it sets with dry circular slurry over the top then that can be fine sanded back straight later. Sometimes I do the second sand back with oil and turps . The dry circular slurry over the top acts like sight lines , the moment they disappear I know when to stop sanding. Cutting back and grain filling can be done like this between coats as well . Its great on timbers that are not stained . It gets a little more tricky if it is stained and you go through in spots . You just have to touch up . If its being done in between coats then the water / glue mix should have a darker pigment added. Anything filling the grain either has to be the same colour as the wood or darker . Never lighter. it looks wrong if it is . Just a touch of Brown Umber with some Black oxide is one way . I use Vandyke with some Black .

Rob