Glyptal & best way to apply it?

I have applied it before. You need a very clean block and then I use a propane torch to wave across the surface.

You might think the block is clean but when waving the torch over the surface all kinds of stuff boils out.

I let it boil out and then wiped it with Acetone. Rinse and repeat until there is nothing left to boil out.

Wipe it all down really good with Acetone until a white rag stays clean and then you're ready to paint it.

Any less effort will result in the paint not sticking properly.

Tom