paulhus@euclid.DEC (05/28/85)
Bubbles in varnish/polyurethane Since I always use polyurethane, this may not be applicable to varnish: I have used a small amount of silicone spray lubricant to keep bubble formation down. It works very well - the resulting surface is always glass-like. BUT, the resulting mixture looses some desirable qualities - IT SAGS like crazy! You can use it only on a horizontal surface, and IT DRIES VERY SLOWLY. I rotated a piece 90 degrees after a day of drying time and it still sagged! Putting silicone in polyurethane: Use a large scrap of wood. Spray a small amount of silicone lubricant into the can of poly. Stir. Brush some of the mixture onto the scrap. Keep adding silicone until your brush-out is free of bubbles. (My total is about 3 seconds of spray in a quart of poly.) N. Chris Paulhus DEC Maynard, MA decwrl!dec-10382!dec-euclid!paulhus
lrolla@cadtec.UUCP (Larry Rolla) (05/30/85)
While in high school woodworking we used to use a propane torch to remove the bubbles from a polyurethane project. You keep the flame about 6 inches away from the surface while moving it back and forth. I used to like this part of the project. :-) I'm not sure that this will work with varnish but its worth a try. LWR
hen@bu-cs.UUCP (Bill Henneman) (06/03/85)
In my experience, brushes are the sole source of bubbles in a finished surface - I use an adaptation of French polishing for everything. Use a pad made of absorbent cotton wrapped in a lint-free cloth (the cotton holds the supply of finish, the cloth applies it). Wipe in a figure 8 motion. For large surfaces, I use a sponge instead of cotton for the center of the pad.