A hindered amine light stabilizer (HALS), which is added to varnishes to protect against photochemically initiated autoxidation due to oxygen and UV light. Tinuvin should be added 2-3% by weight, as soon as possible before use. Varnish to which Tinuvin has been added should not be stored for more than 3 weeks. Tinuvin may cloud damar or mastic varnishes, but letting them sit for a day or two may help clarity, as well as a few drops of Benzyl Alcohol.
Hint: To help weigh small amounts of Tinuvin, measure how many drops weigh one gram.