What's going on with this finish

[Sam Murdoch]

Well alright then enough speculating . I am doing an experiment.

I have 2 boards each with a previously done Waterlox finish.

1) I have just wiped down one (a cherry board) with mineral spirits and with the mineral spirits being very obviously NOT COMPLETELY DRY I have wiped on a new coat of Waterlox Original Sealer.

2) On the second board (this one is alder) I have wiped on a new coat of Waterlox on a clean mineral spirits free surface.

These are both now in a warm dry environment. Before I go to bed tonight - about 5.5 hours from now - I will wipe on a second coat on the Alder sample. This should be 20 hours sooner than the directions recommend and according to Waterlox Central the finish will look like that in Alan's photo. Will see my results in the morning. May not be able to report until tomorrow at this time but I will report. Until then...

Test Results are in:

Both samples previously finished with Waterlox Original Sealer. The sample coat was the same finish

Sample # 1 - Cherry board with wet mineral spirits with a heavy wipe on coat of Waterlox. There are 3 "holes" in the finish - dry spots around which the Waterlox flowed - 2 at about 3/32" and 1 at about 3/16" dia. These holes materialized within the first hour. They would be a nuisance but would easily sand and blend with the next coat. Otherwise a a nice hard even coat after nearly 24 hours of drying time.

Sample # 2 - Alder. In this case I applied a heavy wet film wiped on last evening at 5:30. Did a second coat at 11PM. This morning and now tonight 24 hours after the first coat the surface is not smooth - not leveled out. Not as badly reacted as in Alan's photo but it does look and feel finely textured - like very minute pores throughout the finish. Not an acceptable finish.

Sorry, I can't provide photos. I don't believe that my camera would pick up any detail. If I had a scanner...

Conclusion -

1) The wet mineral spirits caused some reaction issue that I think could easily be blended in with subsequent coats. Still it would be best to make certain that the surface is completely free of wet mineral spirits before applying the Waterlox.

2) The wet on wet finish however would need to be very nearly completely stripped off as both coats have been compromised. A wipe on coat requires certainly more than 8 hours of drying time but this experiment won't tell you if 8 is enough or 12 or 24. Just that 5-1/2 hours isn't and that a wet coat over a coat that is still drying doesn't work. I think that's what Alan had going wrong.

[Chad Bender]

Test Results are in:

1) The wet mineral spirits caused some reaction issue that I think could easily be blended in with subsequent coats. Still it would be best to make certain that the surface is completely free of wet mineral spirits before applying the Waterlox.

2) The wet on wet finish however would need to be very nearly completely stripped off as both coats have been compromised. A wipe on coat requires certainly more than 8 hours of drying time but this experiment won't tell you if 8 is enough or 12 or 24. Just that 5-1/2 hours isn't and that a wet coat over a coat that is still drying doesn't work. I think that's what Alan had going wrong.

Nice test. Those results are completely consistent with the waterlox instructions that the each coat must be completely dry (not cured) before adding another coat. Waterlox sticks to itself with no sanding required, which is a great advantage over some finishes. But if a coat is not dry, subsequent coats will fail. I typically evaluate the surface to see if it's ready for recoating two ways:

First, the smell test. Does the room smell like solvent? If so, the finish is not dry. If not, proceed to step two. (Note that the tung oil smell that is given off during curing is different. That takes several weeks to disipate. But, with a little practice you can easily distinguish the two.) Depending on the room temperature and the amount of airflow, a surface could be dry in a matter of hours or take a couple of days.

Second, the sanding test. Take some 320 grit paper and lightly sand a small test spot. This should produce a very fine, dry white powder. If the surface gums up, it's not dry enough.

I do typically sand everything immediately prior to the final coat, to knock down any nubbins. I'm not sure what purpose sanding between earlier coats serves.

[Alan Lightstone]

Test Results are in:

Both samples previously finished with Waterlox Original Sealer. The sample coat was the same finish

Sample # 1 - Cherry board with wet mineral spirits with a heavy wipe on coat of Waterlox. There are 3 "holes" in the finish - dry spots around which the Waterlox flowed - 2 at about 3/32" and 1 at about 3/16" dia. These holes materialized within the first hour. They would be a nuisance but would easily sand and blend with the next coat. Otherwise a a nice hard even coat after nearly 24 hours of drying time.

Sample # 2 - Alder. In this case I applied a heavy wet film wiped on last evening at 5:30. Did a second coat at 11PM. This morning and now tonight 24 hours after the first coat the surface is not smooth - not leveled out. Not as badly reacted as in Alan's photo but it does look and feel finely textured - like very minute pores throughout the finish. Not an acceptable finish.

Sorry, I can't provide photos. I don't believe that my camera would pick up any detail. If I had a scanner...

Conclusion -

1) The wet mineral spirits caused some reaction issue that I think could easily be blended in with subsequent coats. Still it would be best to make certain that the surface is completely free of wet mineral spirits before applying the Waterlox.

2) The wet on wet finish however would need to be very nearly completely stripped off as both coats have been compromised. A wipe on coat requires certainly more than 8 hours of drying time but this experiment won't tell you if 8 is enough or 12 or 24. Just that 5-1/2 hours isn't and that a wet coat over a coat that is still drying doesn't work. I think that's what Alan had going wrong.

Interesting, Sam. And thanks again for doing the test.

So it appears that you need to wait longer using Waterlox diluted with mineral spirits as a wiping varnish than the typical 8 hours that is often quoted (In fact I'm seen multiple articles/posts on Wiping Varnish that talk about as little as 4 hours between coats if the surface feels dry and not tacky. Fine Woodworking has a nice article on using full-strength Waterlox as a wiping varnish and applying 2 coats a day.) The surface was dry and not tacky when I recoated it, but per Sam's test was clearly not dry enough internally for recoating.

So, outside of not having any brush marks (and Waterlox is pretty good, though not foolproof in leveling out), using Waterlox as a wiping varnish may not have any advantages over using it undiluted as the recoat interval may not decrease with that regimen. It may still be 24 hrs. We don't know yet exactly how long. Likely longer than 5-1/2 hrs, and less than 24 hrs.

I'm trying to determine compatibility with VOC Compliant Waterlox and Mineral Spirits on a test piece I'm doing now. Basically doing 2 coats of 50/50 Waterlox/MS solution. Preliminary look is that there may be compatibility issues, where there absolutely wasn't with the Original formulation. I may try it with Naphtha on the reverse side, as the low VOC formulation has some (15%) Naphtha in it. I wonder if it will work better as a wiping varnish diluted with Naphtha.

[Sam Murdoch]

Just to be clear Alan - I did not dilute these sample - straight waterlox. When I have diluted in the past I use Penetrol - mostly to aid in leveling. That doesn't speed or delay the drying time. I don't think of Waterlox as a wiping varnish I think of it as tung oil with some additives for "enhanced" drying. Tung oil by itself takes days, even weeks to dry, but it is a great finish if you are building A Great Wall out of stones .

Well, after all this we are much smarter. Let's hope it lasts...

[Alan Lightstone]

Sam, I got that. I think there may be a secondary issue that the VOC compliant Waterlox isn't compatible with Mineral Spirits when diluted 50:50 (Actually, I think it was more like 70 Waterlox / 50 MS when I did it). I'm trying to see if that is the issue with my present test. Also whether Naphtha would work to dilute Waterlox VOC compliant version to use as a wiping varnish.

[Prashun Patel]

Alan neither the new or original Original Sealer Finish need to be thinned further. They are already wiping varnishes.

I also just tried a less thorough test than Sam. If I put the SF old formula on top of a surface dampened with ms it looks just like yr surface- that is if I brush it on. If I wipe it on thin it does not bead. If I wipe the surface down completely dry and let the ms totally evaporate for several mins, it brushed on just fine. I cannot explain why the surface tension of the varnish appears to be compromised when doing this, but indeed did happen.

[Kent A Bathurst]

Been following this with interest, because...........

The phenomena is independent of Waterlox, in any of its iterations.

You can accomplish the exact same thing with Behlen's, by using MS to wipe down sanding dust, and then brushing the next coat too soon. You can sand back the resulting unevenness to get it smooth enough to disappear after subsequent coats. But - I ascribe this to surface tension and cohesiveness - the edge of the varnish around the "pull back" areas has created a bit of a ridge, so you are trying to get it level with the surrounding varnish field without flying the plane into the hill.

My heart stopped........it was to have been the last brush-on coat of a large dining table top. Emergency panicked PM to Obi-Wan [aka Scott Holmes], who basically said - let it dry for a day or two, sand it back, press on regardless. That was the one and only time I had used MS for wiping sanding dust. I learned my lesson. After vacuuming, I will always use use what I had used before - DNA. It dampens the rag to lift the dust [actually, I use a small squirt bottle and squirt it on the object, then wipe], and then flashes off quickly.

[Alan Lightstone]

Have to try DNA for wiping sanding dust. I didn't use it initially as the piece had alcohol based dye on it, but after several Waterlox coats, it should have been fine. I'm just in the habit of using the same solvent for wiping sanding dust as is the solvent in the Waterlox, in this case.

Yesterday, I wet-sanded the piece with 320, 400, and 600 grits (again with MS - wish I had seen your post earlier, Kent), then waited 8 hours and reapplied a brushed on coat of Waterlox (full strength). This morning it looks much, much better. Still needs a few more coats, of course, but sanding off the top few coats seemed to do the trick. It wasn't terribly easy to sand off, but nothing crazy. 400 grit as a first attempt wasn't coarse enough. I had to drop to 320 to make any headway.

My impression is still that the VOC compliant Waterlox leaves more air bubbles and seems to have more dust nibs, despite my having my air cleaner at full speed, and a fan/filter going full bore. I clearly like the original formulation better, but can't mix and match now.

[Prashun Patel]

Alan-
You sound like yr well on yr way, but I have a couple comments:

1) It's hard to wetsand with DNA. It evaporates too quickly. Wetsanding with soap/water or MS is usually the easiest. Only after clean up - as a final wipe down might it make sense to use DNA. I'm impatient as the next guy (more so) but the BEST way is to wipe dry, let air dry, then vaccuum.

2) I wouldn't keep the air cleaner on during brush finishing.

Also, just for my own clarification: confirm that you are using the SEALER FINISH product - and not the full strength varnish. If yes, then I've found that it wipes and brushes BEST when unthinned.

[Alan Lightstone]

Alan-
You sound like yr well on yr way, but I have a couple comments:

1) It's hard to wetsand with DNA. It evaporates too quickly. Wetsanding with soap/water or MS is usually the easiest. Only after clean up - as a final wipe down might it make sense to use DNA. I'm impatient as the next guy (more so) but the BEST way is to wipe dry, let air dry, then vaccuum.

2) I wouldn't keep the air cleaner on during brush finishing.

Also, just for my own clarification: confirm that you are using the SEALER FINISH product - and not the full strength varnish. If yes, then I've found that it wipes and brushes BEST when unthinned.

Well, back to just waiting longer and using MS, though I might try DNA to see, but I agree it sure does evaporate quickly.

I am using the original sealer/finish (VOC compliant version) on this part of the table. And now am back to using it unthinned.

Why shouldn't I keep the air cleaner on during brush finishing? I would think (and can demonstrate with my Dylos meter) that the air is tremendously cleaner with it on. Also, I use activated charcoal/pleated filters on mine, so they help somewhat with the volatile organics to decrease their time in the air (though this may be like spitting into a lake.)

[Prashun Patel]

The air cleaner MAKES the air clean. You want to finish in a room that's already been cleaned.

You're basically putting on a fan that draws dust PAST and possibly INTO your wet finish.

I've read it recommended here by Steve, Howie or Scott that the persnickety way is to run an air cleaner in a dedicated finishing room for sometime, then turn it off and let all remaining dust settle on the floor, then change yr clothes and bring in the piece, finish, and leave the room asap.

If yr rubbing out the finish at all, this may be overkill.

Also, you might try wiping on yr final coats (just a thin slicking). That kind of thickness doesn't give dust time enough to settle and dry.

[Kent A Bathurst]

Have to try DNA for wiping sanding dust. I didn't use it initially as the piece had alcohol based dye on it, but after several Waterlox coats, it should have been fine. I'm just in the habit of using the same solvent for wiping sanding dust as is the solvent in the Waterlox, in this case.

Yesterday, I wet-sanded the piece with 320, 400, and 600 grits (again with MS - wish I had seen your post earlier, Kent)......

Oh - no - I don't wet sand, I'm doing between-the coats leveling and dust nib removal with 320. Then I vac, then I wipe with the DNA, just to get up all the dust. I don't see why you can't wet sand with DNA, but it flashes off as Prashun says.

Never saw the need to wet sand for between coats of varnish, to be honest.....never even occurred to me, actually. I sand with 320 between every other brushed coat. After my final brush coat is sanded, I'll wipe on one or two, waiting an hour between them. If I am going for satin finish, I'll use Waterlox for the wipe coats. Comes out fine. I do think I'm going to try the MS and brown paper bag trick though, after a couple weeks curing time.

[Alan Lightstone]

Interesting. I've always wet sanded with 400, about every 3rd coat, then 600 just before the final wipe-on coat. Never thought that I could dry sand the varnish and not clog the sandpaper with those grits.

I'm dying to try the brown paper bag trick too.

[Kent A Bathurst]

Well........the battle orders I operate under say no sanding required between coats if I can get the 2d coat down in 12 - 24 hours. Beyond 24 hours I sand. Usually I'll wait 36 - 48. If you are getting gummy stuff, then it isn't dry enough, I'd guess. I get fine, amber dust.

Again - I use Behlen's, and the Wlox wipe on for satin. But everyone's said that Behlens and Wlox are equivalent in use. Dunno about the low VOC stuff, though.

[Prashun Patel]

You can dry or wetsand between coats. It's not really needed for adhesion purposes - just leveling. If yr surface is smooth 'enough' you'll be able to buff out minor imperfections and dust in the end. I choose to wetsand with MS between every couple coats because I find it a little less aggressive than dry sanding, and I tend to get corns when dry sanding.

Newer stearated sandpapers (according to Jeff Jewitt) are a better choice because they let you see what yr doing better, can used dry, and don't leave material that is incompatible with most varnishes. I used this kind of 'carborundum' sandpaper once and it was wonderful.