UMTON cobalt siccative 100 ml is the best siccative for artistic oil painting. It’s added for quicker drying. It’s very concentrated, as it contains 1,5% of cobalt. In normal use, it’s added drop by drop. You can add up to 5 ml of cobalt siccative per 1 l of pure linseed oil. A larger amount isn’t suitable because the top layer dries very quickly, but then the deeper paint dries with difficulty. The contents of the bottle are enough for 20 litres of linseed oil.