No Carcinogenic Fumes,
Fat over lean is a fundamental technique that every painter should be aware of. If they wish to have good adhesion of paint layers and prevent cracking, delaminating, imperfect drying, and uneven gloss in their painting then they should always paint fat over lean. This means to paint so that each successive layer of paint is fat and contains more oil than the lean layer preceding it.
Don't be mistaken, a fat layer of paint has nothing to do with the thickness of the paint. Fat over lean refers to the amount of oil in the most recent layer of paint relative to the dried layer below it.
Chelsea Classical Studio's Lean Medium consists of linseed oil and lavender spike oil essence – a historically documented, alternative solvent for painting that is safer to breathe than turpentine. Lean Medium will thin the paint and make it dry faster. It is recommended for early stages of painting. Chelsea Classical Studio's Fat Medium is a mixture of linseed oil, lavender spike oil essence, and damar resin. Fat Medium will make the paint more glossy and dry faster. It is recommended for later stages of painting.
Chelsea Classical Studio has made painting fat over lean easier and more intuitive than ever. To paint fat over lean, begin by using our lean medium and simply add more fat medium each successive day of painting and, towards the end, switch to fat completely.
“Whatever technique you use when painting in oil, the tradition of 'fat over lean' should be observed. 'Fat,' or more oily paint, must always be applied over 'Lean,' or less oily paint...”
~Mark David Gottsgen (1948-2013),
excerpt from The Painter's Handbook