The finished layer can be 1/2 to 2 inches thick, and once dry is sealed with a drying oil (like linseed oil).
en.wikipedia.org Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil, and walnut oil.
en.wikipedia.org These are triglyceride-based, and include cooking oils like canola oil, solid oils like cocoa butter, oils used in paint like linseed oil and oils used for industrial purposes.
en.wikipedia.org This line includes thinner, linseed oil, safflower oil, stand oil, painting medium, fast drying medium, and impasto medium, as well as gloss varnish, matt varnish, satin varnish, and varnish remover.
en.wikipedia.org He knew that most substances expand when heated, so he took a container of linseed oil and measured its change of volume against his reference points.
en.wikipedia.org