Shellac or Vinyl Sealer under nitro
 

There's a debate on my banjo builders forum about sealers to use under nitro. Most agree that for banjos, vinyl sealer is fine, but there was some belief that custom guitar builders prefer shellac as a sealer because it doesn't build as much as vinyl sealer thereby causing less dampening. I'm curious for opinions from the SSGs here.

I am not a fan of vinyl sealer. It is thick, doesn't sand well, and produces a bluish, milky cast when viewed in certain types of light. I use shellac, or nothing at all.

Shellac is the bestest.

Sticks to everything.

Everything sticks to it.

Mostly.

Mix your own from dry flakes and fresh alky or use Zinnser Seal Coat. Commercial liquid shellac can have lotsa wax and other contaminants - stay away from that stuff.

I always mix my own shellac. I swear it dries harder than canned stuff.

Anyway, what # cut do you guys use as sealer? How many coats?

I use neither and have had no finish issues.

You don't need any sealer under nitrocellulose lacquer. It adheres well to all the woods used in guitar making, with no undesirable interactions.

I use shellac (about a 1-1/2 lb. cut--no precise measurement needed) on the raw sanded wood for two purposes. First is to raise grain and set up loose fibers for sanding, which matters mostly on the top. Second is to keep the pore filler from staining or discoloring anything. You need enough to get an unbroken coat and no more than that. Usually a double coat, sprayed in one session, is sufficient.

After pore filling, I sand back to wood, and then go right to the nitro lacquer.

Zinsser Seal Coat comes dewaxed and 2# cut, and I've never had a problem with it, so I don't mix my own flakes as often as I used to.