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I am towards the end of finishing a bench that has paduak. The wood (I found out after the fact) is quite oily and so the finish takes forever to dry. It also turns out that it loses its red color over time, so I won't be purchasing it again.

I waited on the finish for a couple of days and it finally hardened (total of about 4-5 coats of arm-r-seal gloss rubbed on.

Afterwards to prepare for the final coats I wet sanded the finish with 600 grit and soapy water. Unfortunately the slurry has settled into the wood pores. It appears very white when the piece is dry.

I have tried using mineral spirits to get it out. It looks fine with the mineral spirits on, but once it dries the white shows back up in the pores. This gives me hope that maybe if not completely cleaned out, it will not be so visible with a layer of finish.

Anyone got any experience that can chime in? Thanks, john

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    Your solution is exactly what I was going to suggest as one fix John. By adding more finish you permanently 'wetted' the residue, and as you can see this makes the dry dust essentially invisible (it's not completely invisible, but close enough in most cases). – Graphus supports Monica Feb 14 '17 at 9:35
  • I'm having a very similar issue. I wet sanded GF High Performance Gloss with 1500 grit. White slurry was left behind. Wiped with mineral spirits and all seemed fine. But the white spots remain. Almost looks like faint dried water spots after wiping with the microfiber towel. I'm tempted to just spray on another layer of gloss after reading your post. Does this sound like what you encountered? And after your last coat dried, was the residue not visible? Many thanks! – Nat2233 Jun 15 '17 at 14:15
  • @Nat2233: yes it sounds exactly like what happened to me. Adding a final layer of topcoat w/ extra care made the white spots disappear and I was very happy with the finish. After the final coat, it looked as it did with the mineral spirits on wet. – jbord39 Jun 15 '17 at 19:33
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The white residue is abraded varnish, settled in the low spots. Ideally this should be rinsed or wiped away as the final stage in the wet-sanding before moving on to the next step. A damp microfibre cloth is an excellent tool for doing this, but just flushing the surface with water and any cloth will get rid of it, just as everyone had to do before microfibres came along :-) I've even seen some finishers using their hand as a type of squeegee when wiping the surface down, although I'm not convinced this is better than using a cloth.

I have tried using mineral spirits to get it out. It looks fine with the mineral spirits on, but once it dries the white shows back up in the pores. This gives me hope that maybe if not completely cleaned out, it will not be so visible with a layer of finish.

Yes exactly so. When you apply varnish this is said to wet the surface and the effect as you've now seen is permanent. This is much the same as the difference between bare sanded wood, which looks pale and dry, and the richer colouring once the first coat of any finish goes on, wetting the surface fibres. Note that the wood is still said to be 'wet' by the finish after it has dried.

Some addition points:

Do all your sanding in one go
You can do all of your sanding at the end, so rather than sanding to prepare the surface for the final coats as you've referred to you are smoothing off and perfecting ("flatting off") the surface of the varnish.

Sanding between coats isn't necessary unless you're removing dust nibs or other defects — on most finishes it is not needed to ensure bonding between one coat and the next. All excessive sanding between coats is doing is removing finish you don't need to remove and slowing down the whole process.

Bit more on this here:
Leveling a finish/finishing the finish

Grain fill/pore fill
You can fill the wood prior to applying the final finish to minimise the potential for this problem. If the wood's surface is very flat and smooth to begin with you won't easily have any low spots that can harbour sanding residue.

With varnish, which can have a very substantial body so it builds thickness well, you can fill grain using the finish itself (often done by luthiers for example, usually with shellac in that case but the same principle applies with most film finishes).

Another option is to sort of do both things at once, by sanding in the first coat of varnish. This creates a slurry of wood dust and varnish, which is an excellent grain filler and of course you have no worries about any compatibility issues between the fill material and your final finish since they share the same binder.

  • Thanks. I wanted to avoid a grain fill because I do like when the surface has a more natural look rather than like full on glass, with dimples into the pores and perhaps indention lines into any long grain pores. I see wood like this all the time but getting a finish like that is elusive to me :P – jbord39 Feb 14 '17 at 15:07
  • @jbord39 I like that level of finish on open-textured woods very much myself. When you say you rubbed the finish on, are you applying it like wiping varnish? – Graphus supports Monica Feb 14 '17 at 17:25
  • Yes I used a cotton cloth which I leave soaking in the arm-r-seal and just wipe it in in circular motions when I apply a coat. – jbord39 Feb 14 '17 at 17:31
  • I find I get much better results when wiping on varnish if it's diluted some. You can wipe on straight varnish certainly, but it'll tend to lay flatter if a little thinner than as supplied in the tin. – Graphus supports Monica Feb 14 '17 at 23:02
  • Thanks. I got some bubbles after wiping on and managed to blow them out with some quick puffs of air. Is there another way to deal with any bubbles? – jbord39 Feb 14 '17 at 23:36
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Traditionally "tack cloth" is used between finishing coats to remove any dust from previous sanding or from the atmosphere. Basically it's a cheesecloth with a mild adhesive on it.

It has fallen out of favor in recent years due to the risk of the adhesive contaminating subsequent coats of finish.

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    AFAIK, it's actually varnish on the cloth. You need to use a light touch with them to prevent rubbing onto the surface – Steven Feb 14 '17 at 1:11
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    Microfiber dusting cloths work just about as well as tack cloths, and can simply be laundered for reuse. And you don't have to worry about them drying out or spontaneously combusting... – keshlam Feb 14 '17 at 1:31
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Well I got impatient and just put on another layer of the arm-r-seal about 3 hours ago. It filled in the holes and made the white poly-slurry filling the pores invisible.

I also tried (beforehand) vacuuming out the white powder but was unsuccessful.

I would still be interested in what methods others use for this situation.

Thanks, John

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You can also try blowing out the dust with an air compressor.

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