I have a piece of Walnut that I am finishing with Waterlox, and even after the third coat, with 0000 steel wool between coats, I still get a distinct grain pattern in the reflected light. (ie. the pores are still open)
Do I have to use a pore filler to get a relatively smooth finish? While wet, the luminescence of the grain is beautiful. However, once dry, the reflection detracts from this due to the finish conforming to the pore structure.
In a past project, I finished Mahogany (not quite as open pore as Walnut, but similar) with Minwax clear spar varnish, and after the third coat applied in the same fashion, I had a nice, smooth finish. Is what I am getting with the Waterlox due to the higher viscosity? Do I just need to cycle through a few more coats of Waterlox with 0000 between coats until I get a level surface?
Mark
Replies
Mark, Waterlox is a thinned wiping varnish. Because it is thinned, it will take many coats to fill the pores. Using a brushed, full strength varnish to fill the grain, then sanding smooth followed by a couple of more coats of the Waterlox will give you faster results.
Even faster, would be to use a grain filler first.
Stick with the Waterlox, just keep building it up. I have found the satin waterlox to building a little quicker than the original (may just be me). It sould even out after 6 coats and the look will be well worth the effort!
Aaron
I disagree that continuing with the Waterlox will eventually give a level appearance. I do agree that the surface of the finish will be beautiful, but even with a dozen coats, the "dips" into the grain and pore structure will continue to show. This is the nature of the very thin film that results from a wiping varnish/oil and is desired with this type of finish.
If you don't want that grain structure to show, and want a smooth surface film, you must first fill the wood with a silex filler or a wood slurry before applying the finish.
Rich
Hmm...Already have 3 coats, so I suppose it's too late to go back to the pore filler ? I'm leaning towards the pure varnish 4th coat (Minwax clear spar varnish) followed by another Waterlox coat.
If anything, this is good practical experience for my next Walnut project. At least this is just one board face and not an intricate work of art. If I have to sand it all down and start over (last resort!), it's not the end of the world. I appreciate the pointers!
Mark
Mark,
Level it carefully with 320 grit and apply varnish, either alkyd or poly with a brush - but not spar varnish! You may want to brush another coat on after that.
After a brushed on varnish, there is no need for Waterlox.
Rich
As the others have indicated, 6 coats is the majic number for me.
I agree, you have already started so it is likely too too late for a grain filler. Stick with the waterlox, I personally wouldn't switch to Minwax. Waterlox is thin and won't completely fill, but will give a beautiful finish. If you do switch there is no need to topcoat with waterlox at that point you maybe asking for more problems than you will solve.
Aaron
Any film finish can be built to the point where the grain is fully filled. It just takes lots of coats, patience and periodically sanding back the finish to level. Once the finish sands to a level surface--you no longer see shiny areas in the grain or pores--the pores are filled. At this point, a final finish coat will give you a perfectly flat, grain filled finish. All grain filler does is shorten the process considerably.
As I said before, using full strength, brushed one coats will make it go faster. You don't need to worry about brush marks as you will be sanding the surface flat anyway. You're just trying to get material into the grain depressions or pores. I would not use Minwax Spar Varnish. Spar varnishes are soft and do not sand well. Use a fast dry interior varnish.
Finally, filling using finish requires that you put on a lot of material. This means that it will take quite a while for the finish to fully cure and it should be fully cured before you attempt to flatten the surface. Sanding too soon will go through the hardened outer film but the inside layers will still be soft. This makes a mess. With varnish, the curing process could take up to 4 weeks.
I dropped by my neighborhood Highland Hardware today (Couple of blocks away <grin>) to get some full strength varnish, and learned a few more details that were escaping me.
The use of 0000 steel wool between coats only burnishes the finish. Meaning I'm not removing finish between coats, I'm merely rounding over the ridges on the pores and creating a tooth for the next coat. So, with that method, it doesn't matter how many coats I use, I will have valleys in the pores and the problem never really goes away. I didn't realize this was the case, since it appears to the naked eye that I had removed finish. A much better method is to use a cabinet scraper between coats to get back to bare wood. A scraper is effectively 220 grit sandpaper, but it doesn't gum up. This technique will get me to a relatively flat surface, as I'm removing finish all the way back to the bare wood, but not the pores. Also picked up a quick demonstration of flattening and burnishing the edges of the scraper, followed by an actual scraping.
I also picked up a can of pore filler for my next project, but I also learned a good technique for when I don't want to use pore filler.
Mark
Whether you use a scraper--which, by the way is an excellent way to flatten a finish--or sandpaper with a backer pad, you need to get down to the wood in the high part of the grain. Either will work.
Another method that helps fill the pores when using waterlox or other wiping varnish is to apply the finish and then wipe off with a clean rag. several coats like this will also concentrate the finish on the low areas and pores.
Aaron
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