Re: Wet sanding?

I "wet sand" finishes but not bare wood. The main finish type that I wet sand is when I'm going for a "piano finish" on something. For instance, the oil drop turnings that I made about a year ago had around 20-30 coats of black lacquer on them. Between each coat of lacquer, I hand sanded from

600 - 1200 grit with water-soaked wet/dry automotive sandpaper. I tried several different lubricants (the "wet" in wet sanding of finishes) but water worked best this time. This gave me a great, deep, wet look that I wanted. Had I gone longer, I would have developed a highly polished, mirror-like finish effect instead of a dead black "oil" effect that I got.

Otherwise, I think maybe you're just thinking of raising the grain in order to sand it off and get a smoother finish? If that's the case, then I do that all of the time with flat work, not too often in woodturning. However, I don't use water. I use a faster evaporating liquid like mineral spirits (pretty quick) on up to toluene (nasty stuff but evaporates really quickly) so that don't have to wait around to finish things up. Using water: just use a spritz bottle and spray the wood a little all around. You don't need to soak the piece. Wait however long to let it surface dry and raise the grain. Sand very lightly with your final grit sandpaper. Don't wet your sandpaper.

On the other hand, you may have heard of the process of sanding woodturnings when wet either by water or wax or mineral oil. I believe in most of those cases, it's the slurry that's often produced and fills in the pores of the wood that's giving the smoother feeling to some woodturnings. I don't like the look of pieces where this has been done as it looks muddy and fuzzy. No clear definition of the grain, etc.

I don't like to do this with anything but tough pieces that are going to be finished with mineral oil (plus other stuff maybe) anyway and are experiencing bad problems with tearout. For the truely terrible pieces with tearout problems, I use other methods but that's a different discussion. The mineral oil (or equivalent) will help to stiffen the fibers and fill the intra-fiber areas so that I can more easily shear them off with a tool. But then you tend to have other problems such as the muddy appearance mentioned above.

Hope this helps,

- Andrew

Just out of curiousity ... do people wet sand their lathe projects much? > > I never have - I have just gone up to 600-800 grit and called it good. > > I understand (I think I do) the purpose of wet sanding (opens grains more > etc), but what is the best technique to do it? Actually put a damp cloth on > the piece and then let it sit for a bit (x amount of time) and then sand it > from there? Put a bit of water etc on the sand paper? Maybe I am way off > base here ... > > Thanks > Darren

I only use water as a wet source if I'm going to apply some other water-based material such as a water-based aniline dye. I will apply the water with a paper towel and then dip the sandpaper, typically 400 grit or finer, in the water and sand.

For non-water-based finishes I have used Lee Valley Polymerized Tung Oil Sealer, Watco, mineral oil and perhaps a few other things. Not everybody thinks wet sanding is great but I find it is one of the effective ways of dealing with end-grain and other rough-grain problems. Like using water I will wet the piece with the solution using a paper towel and then apply some solution to the sandpaper. It creates a fine slurry while you are sanding. I always wipe the piece down after sanding to get rid of any of the slurry.

Give it a try. Billh