Siccative or Dryer is the name given to certain preparations which

There are a variety of oils manufactured for the use of artists: linseed oil, nut oil, pale and dark drying oil, poppy oil, etc.  For ordinary use the most satisfactory is the poppy oil, which can be obtained from  any dealer in artists' materials.

Siccative or Dryer is the name given to certain preparations which, when mixed with paints, cause them to dry quickly. There are a variety of such preparations, among which the best known are Winsor and Newton's drying oils, Megilp, Siccative de Harlem, and Siccative de Courtray. The drying oils are seldom employed now, while Megilp, a sort of jelly which comes in tubes, is almost entirely out of use among artists. Siccative de Harlem is still found in some of the older artists' color boxes, and is used in the proportion of one-half Siccative to one-half oil. The best of all, however, and that most generally in use among French and American artists is the "Siccatif de Courtray."  This is a dark brown fluid imported in small square bottles, one of which will last a very long time if kept carefully corked.

The Siccatif de Courtray is used in the proportion of one drop to five of poppy oil. This is a safe allowance, as too much might cause the paint to crack from drying too rapidly. If using transparent colors, such as madder lake or rose madder, siccative should always be mixed with the oil: if one is painting on the same canvas every day, it is well to use the siccative also, but for a painting which is only taken up occasionally and has plenty of time to dry, it is not necessary to use any siccative, the oil in itself being sufficient.