Bob Couch replies: I do use wet-dry paper in my Waterlox finishing process but not during application, only during rubbing out once the piece has cured.
I would think that using abrasive paper would add loose wood fibers to the finish when you want a dust free clean surface during the finishing process.
The process for applying Waterlox (furniture not turned pieces) I have had the most success with, starts with a surface that has had the grain raised with water and scuff sanded with the next higher grit than my final grit. My final grit is usually 220 or 320. If I have end grain that will be finished, I may go up to 400 or 600 on just the end grain and do a wash coat with dewaxed shellac before finish. This helps keep the end grain from being much darker.
Waterlox will penetrate the wood surface very nicely so I want my first coat to really saturate the wood before it dries and won’t absorb and further. To accomplish that, I use a foam brush to apply a heavy coat and continue to brush on additional coats to any areas that soak up the Waterlox more than other areas.
I will let the first coat cure for a minimum of 24 hrs. If there are any rough areas, I will scuff sand them with 320 before adding my additional coats.
I have the best results with a good quality foam brush when adding coats. After 3-4 coats, I will usually wet sand with 320 or 400 wet-dry paper before adding another 2-4 coats depending on how open the grain is and if I’m using finish to level it.
After a minimum of a week’s time to cure, wet sanding with a cork or felt block helps to keep an even pressure and the wet-dry paper won’t load up and damage the finish. I will usually will start with 600 or 800 paper and go up to 2000 or 2500 grit. You can find these grits at Klingspor, which is where I buy pretty much all of my abrasives—woodworkingshop.com.
Once the finish is level, depending on the sheen I’m looking for, I will use 0000 steel wool to apply a good quality furniture wax followed by rubbing out the surface with a white Scotch-Brite pad to burnish and bring the surface back up to the sheen I’m looking for be it a soft gloss or a high gloss finish.