The is quite simply the BEST black shielding paint available ON THE PLANET!
I spent many years buying this exact formula from an aerospace supplier. Expensive as hell but the best! Thick, lasts forever, goes on in a single thick coat, and HIGHLY CONDUCTIVE. I liked it so much I went to the manufacturer and bought a metric ton of it to get the price down. This is American made, bottled in America.
DO NOT CONFUSE this with the lame watered down stuff they sell elsewhere- This is the best.
I package a 1 ounce bottle with a nice stiff brush. This is water soluble so cleanup is a snap! This stuff is so thick and adheres so well I think you'll be able to do 4,5 or even 6 guitars with one bottle!