Shellac primers or sanding sealers are so thin it is like painting with water. But, they dry so fast when the stuff runs it doesn't do much harm. I always just brush it on, using a very, very cheap brush and disposing of it when I'm done. I'm not sure I want to spray an alcohol based substance, because of the flammability and the stink. But, it does come in spray cans. My preference of those products is the "sanding sealer" variety, which is clear.