Grain-Filling and Finish Efficiency

Can any formula fully fill grain with just one coat? Finishers kick around the time-consuming process of achieving a totally smooth surface. September 14, 2006

Has anyone tried MLC's Level post-cat, high-build sealer? I've been told by their rep that it can be built to 10-14 dry mils and is a more affordable alternative to using 2K poly for a high-build finish. Designed for use under CV.

Forum Responses
(Finishing Forum)
From contributor A:
I just used it for the first time on a mahogany job. In my humble opinion, it isn't as good as they say for fully flattening a surface. I applied the first coat thinned 30% and two coats out of the can. Sanded flat with 320 between each, two comfortably wet coats of Magnamax, the first sanded with 320 as well.

The problem I had was, first of all, a small amount of finish pop that I just couldn't fill no matter how wet I laid it down. The second problem was with the way it flashes. Because it is so thick in the grain, the finish in the grain will at first (minutes after spraying) stand proud of the surface. It will in time flatten, is sanded, etc. I did the whole finish process in twelve hours and had a glass smooth surface. After three days when the finish was done curing, I had visible grain texture on the whole surface. It was still a very nice finish, but not full flat. I suppose you could allow each coat to set longer if you have the time. It would work well on tight grained woods.

From contributor R:
The only finish that I can think of that you can get a full fill in only 1 day, without shrink back, is 100% solids UV. All other finishes have solvents in them that need to evaporate. As they evaporate, the film shrinks. The more layers you put on in a relatively short amount of time, the longer it is going to take for the solvent in the bottom layers to evaporate and then shrink. That is why the finish looks flat for a while and then suddenly dimples. This is part of the basic chemistry of these products.

Taking this principal into account, I recommend, for best results, shooting only 1 coat per day, sanding the next day and recoating. This way you allow the finish to release the majority of its solvents and shrink back before you sand it flat. This holds true for whatever finish you use. The more you put on at one time, the longer you wait before you recoat.

I know you are going to say that you don't have time to wait a day per coat, but do you have the time to re-do the job, or worse yet disappoint the client? You need to explain to the powers that be that these finishes take extra time.

From contributor W:
Extra time means extra money... Don't shortchange yourself.

From the original questioner:
Contributors R and W are both right. Time is money, yet a good product is a good product. I recently sprayed (with MLC's CV200 varnish) a zebrawood vanity top. Very open grained. My first three coats were thinned 50% and sanded way hard with 180 and 220 using a jitterbug-type sander. Next three or four coats got the same treatment but weren't thinned, but they were all cut way, way back. In the end I bet I only have 3-5 dry mils on the thing, but it's mirror flat. But that was a lot of coats and I did it over several days (just working it in with other stuff). Quite a nice looking top.

From contributor A:
You're missing my point, contributor R. I understand the principle of shrink back. I don't think it is efficient to use a sealer as a grain fill if it ties up your spray booth a day for each coat. Not only that, from what I've heard, most people that use it thin it to get it to lay into the grain (even my rep said as much). Isn't that like going back to square one? I liked my final finish using it, but I wanted the questioner to hear my struggles. Next time I will grain fill with a paste filler and then maybe use the level sealer over top.

From contributor R:
Even with a paste wood filler, I let the paste dry overnight and then I still only shoot 1 coat per day. Personally, I think paste filler is the best way to go, especially if there are mouldings or if there are any details shaped into the wood. Even on a flat panel, I don't think you save any major time by using a finish as a filler, unless you are using a widebelt to do your sealer sanding.

From contributor D:
Polyester is the nuts for this purpose. Absolutely non-shrinking and you can spray anything on top of it. Somewhat difficult to use but once mastered, polyester can't be beat.

From the original questioner:
It also can't be afforded. Just joking, of course. If the customer is willing to pay, it's worth it. I got a quote from ChemCraft on enough polyester to cover a mahogany chest of drawers and dresser unit, and they wanted over $150. I can get a 5 of conversion varnish and spray the whole can of it cheaper than that. By the way, I've been told that some polyesters (3-part finishes) have to be mixed very cautiously because improper mixing can cause it to flame up. Is this true? Aside from its pitfalls, I'd like to spray it one day. Sounds like fun.