Avoiding Dust In Your Finish

Article - September 12, 2007

This week’s question comes from Jason. He writes:

No one has ever answered this directly for me, and you are becoming my trusted source! :) It has to do with finishing and dust getting on the finish…I mainly use tung oil now and that fixes the problems since it soaks in and doesn’t sit on top of the wood, but in the past whenever I used polyurethane when it was dry the board felt bumpy and looked bad b/c of all the crud that settled in the finish…I have tried cleaning up the shop to the best of my ability and I can’t seem to keep dust out when using a poly or something similar…And if I sand it out and recoat, it is just back again…How do I get rid of this damn dust in the air???? Is there some trick I am missing, it drives me crazy and actually I stopped woodworking for a long time b/c I could never seem to get a decent finish which frustrated me to no end…I now have a better shop and I do have a Delta air filtration unit, should I leave that on when finishing??? I just figured it would stir up the airborne dust particles more…I thought maybe finishing in a different room, but even my bedroom has dust particles floating around, I can see them in the rays of sun coming through the windows…And my house isn’t dirty or anything, I always figured some dust is just normal always in the air…Help a frustrated brother out, lol…I appreciate any help you could give me on this subject.

And here was my reply:
“Hey Jason. Take a deep breath. We all deal with these issues so don’t get too uptight. There are a few tricks and some standard practices that should help you out. First, you should try to reduce the shop dust as much as possible. Vacuum the area thoroughly and turn on your ambient air cleaner the night before a finishing day. You are right about keeping the cleaner on while finishing. That will only stir the dust up and create more problems for you. Now if you really want to get crazy about it, you can even wet the floor down around the finishing area. This will cut down on the dust created when you walk around. I never really do this though.”

“Once the prep work is done, you can start your finishing. When using poly, you have a long cure time right? And that’s the problem. While the finish cures, dust settles in it. So one thing you can do is start using a wiping formula (if you are not already). The wiping formula is thinned with mineral spirits, and will dry faster than full-strength varnish. You may have to apply more coats to get the finish thickness you want, but that’s a small price to pay for less dust-nibs. Now once the finish is dry, you should lightly sand with 320 grit and apply the next coat. Repeating this process, you won’t have a problem until the final coat (as you found out). For the final coat, I typically thin the varnish as much as 75% with naptha instead of mineral spirits. The naptha flashes off quickly and dries before lots of dust has time to settle. If you can spray this coat with an HVLP system, you are even better off. Now once this last coat dries, it is inevitable that you will have an occasional bump. I take care of these with a light touch of 2000 grit automotive sandpaper. The 2000 grit is aggressive enough to flatten the nibs but fine enough not to scratch the finish. Don’t rub too hard. Just a few light passes will do the trick. That should leave you with a nearly flawless finish. And with practice, the results get better and better. Hopefully that will put you on the right track. Good luck!”

Discussion

techie September 12, 2007 9:10 pm

The info you gave is perfect. I even once tried to use a piece of tarpolin suspended about 1 foot over a huge panel i was finishing some years back. It actually worked, but it took forever to setup. I also use wipe on poly, and do thin it on the first and last coat.

Another idea is to have a higher temp in the shop as well. A temperature of 10 degrees higher than standard room temperature also helps the finish cure faster.
Also you may want to try water-based finishes! In some cases, they can dry faster than shellac finishes. I find that major horizontal surfaces (tables, chests, dressers, etc.) need tough oil-based finishes. But the sides (gable ends), i use water based with great results.

The smell is greatly reduced, and you don;t have to wear a mask (you should always anyway)! But with oil, it can be unbearable in a small space.

Peace

Reply
LordLQQK September 13, 2007 5:33 am

Great info. On oil poly you might want to use water when you use the 2000 grit sandpaper. It is wet/dry super mega fine stuff and can give you a mirror like finish with high gloss poly. Use a spray bottle and lightly mist the surface, this will keep the paper from clogging and it acts as a lube for the sanding. Sanding block/sanding dowels should also be used wherever possible.

LQQK

Reply
David Caskey,MD September 13, 2007 7:11 am

I had a large piece to finish and obtained a very good result by simply hanging some clear plastic sheeting from the ceiling. This worked great and was simple to construct. From watching the painters who work on my house, I get the idea they do the same when applying varnish and poly.

Reply
Mark Salomon September 13, 2007 3:26 pm

I use a coat or two of brush on poly sanding with 400 between coats (you really need to let this dry or it will pill up when you sand if it’s not dry). I’ve found that wipe-poly by itself doesn’t give enough of a base unless you put about 10 coats on and I don’t want to spend this kind of time. To prove to yourself how little wipe-on goes on try measuring the amount of wipe-on poly that you actually use for a coat and and you’ll be amazed at how little goes on. Anyhow, after it’s dry wipe a couple of coats of wipe-on poly with a light 600 sanding in between. You can finish with a final wipe-on satin, a light rubbing with 0000 steel wool followed by wax, or simply a coat of wipe-on gloss poly if you want a higher sheen. Virtually no dust problems and a great finish.

Reply
bobby russell September 30, 2007 6:42 pm

Good info guys , i would like to add a couple of things if you are using a sprayer and have the compressor or tubine have them outside the room and just before you spray or brush boil an electric kettle once or twice depending on the room size half an hour before you start painting .what happens is the steam rises and and when it falls it takes it the dust with it and helps a great deal with you finish. good luck..Bobby

Reply
C Ed Wright October 4, 2007 7:57 am

Dr. Caskey’s plastic attracts airborne dust via static electricity. Great if that’s the problem. That’s like planting dill near tomatoes to divert hornworm caterpillars (because they prefer dill to tomato plants!). However,

Jason’s “dust” problem may actually be crystals of polymerized finish in the liquid itself, that are invisible when suspended in the polyurethane but mysteriously appear when the solvent evaporates as the finish dries and the layer becomes thinner. If no dust-control solution seems effective, this may be what’s happening, especially if it’s been around a while. In that event, simply filter the contents of the can into another, perfectly clean, container. Before returning the filtered liquid to the original container (if you choose to), you must first thoroughly clean all residual liquid from that can, because it will also contain some of those crystals. It might be easier to simply use a new empty can from the paint store/department and label it with a magic marker.

Reply
Alan Bland January 19, 2020 4:10 pm

I have a designated spray room 8×9. With 21”x21” fan in wall and a 14”x20” furnace filter at the top of the opposing wall. I have a moisture and particle filter after my standup Gindy compressor in another room and one 25 ‘away and than a small one on my gun. I vac and tack and strain my water white conversion varnish and from a high quality gravity feed gun. I still get more than few particles on my furniture tops. The best advise I’ve heard yet is sprayed by a electrostatic spray to bring partic ok Ed down. I truly appreciate an advice I can get. Thanks

Reply
Ruadh April 20, 2020 11:19 am

If it is a small piece, build up your finish in the shop and lightly sand. When you are ready for that final coat or 2 where you really need to keep the dust out, thin the varnish down like people already have suggested, but go run the shower in your bathroom nice and hot for a while. Let it run long enough to steam up the mirrors real good. Now wait for the humidity in the bathroom to drop to acceptable levels and now you have a room with virtually no dust in the air. This is a trick people use for cleaning camera sensors at home.

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Amy November 26, 2020 5:51 pm

Thought I’d jump in and add this tip as it might not be super obvious to some, but what you wear while you work can have an impact on your finish. If you wear something prone to pilling/putting off fibres it’ll easily shed onto your project. Tightly woven fabric garments are best. If you roll a lint roller over your shirt and you see tons of lint you’ll know not to wear that in the shop.

Reply
R Webb December 15, 2020 10:25 am

You can just delete this entry if it’s inappropriate. I have a ‘similar’ problem that is making me crazy! I wonder if a question from a non-carpenter will be noticed. I purchased an Eddy Bahama console (crafted from Ribbon Stripe and Quartered Mahogany veneers in dark Kona finish.) but I can’t keep it dust free. Using dust free cloths etc, but dust just moves around. Any suggestion would be gratefully received!

Reply
- Marc Spagnuolo December 15, 2020 2:29 pm
  
  We just use a microfiber cloth with just a bit of water in it. Grabs the dust well enough for our purposes.
  
  Reply
Danny Byrd jr February 7, 2021 1:53 am

Hello, I newly stained a gun stock and as it’s drying I see alot of dust settling in the wet finish. I want to remove this before I apply a clear gloss finish here soon. Any ideas on removing the dust would be greatly appreciated.

Reply
- Marc Spagnuolo February 7, 2021 10:21 am
  
  A light sanding with 320 should do the trick.
  
  Reply
keith January 23, 2022 9:08 pm

I am a furniture refinishing hobbyist, refinishing in the basement of my ’30’s house. While I appreciate many of the tips regarding minimalizing the dust, none eliminate it (you can sand it out of the previous coat of tung oil until the cows come home but, without an elaborate dust controlled room [$$$], nothing is going to prevent it). I’ve become resigned to the inevitable – I’m going to have dust marred ‘finished’ tabletops and the only remedy is an “after the fact” rubbing compound once the final finish is securely hardened. Can anyone advise me as to what that compound might be (toothpaste??). Thx!!

Reply
Kevin August 16, 2022 6:00 pm

Had a nice live edge pine bar installed with an addition. A contractor put a couple of dings in it so I decided to strip it down and put a new clean finish on it. First attempt I tried the 3x water-based poly. I have never worked with this stuff before and I just could apply that heavy of a coat to make it work. Thin coats dried too fast and I couldn’t keep a wet edge. Stripped it down and tried the standard water-based poly. Again it just wanted to dry too fast. Applications are being applied indoors with the temps below 70 degrees. Now I have gone back to the old reliable oil based poly. Sand, tacky cloth, mineral spirit washed. Twice I’ve done this and the dust bunnies are evident.
I am going to try and use a 400 grit to remove the dimples and apply a thinned poly.
I’ve been reading many blogs. Looking for a miracle I guess.

Reply

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Avoiding Dust In Your Finish

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