For sealing a head without a gasket. EC Birt's solution back in the day was to go to a paint store for a can of silver paint, he would reach back and get the one that has been sitting undisturbed for the longest time. Without disturbing the paint he would drain off all of the can's contents but the gooey residue paste at the bottom. He would "paint" the gasket surface with this goo to create the seal.
"I couldn't wait for success, so I went ahead without it."