Petrochemical solvent to make the varnish more fluid.This irritant solvent can cause headaches and is harmful to the fetus, it is a carcinogen and neurotoxicant, capable of attacking the nervous system. Even in small quantities, it is better to avoid breathing it! 

L’Atelier Green has replaced it with biosource solvents: ethyl acetate (sugar cane) and butyl acetate (cassava)