Dammar or soft copal varnishes are soft, very flexible and transparent, but dry slowly. These varnishes have a bright appearance and a faint pale yellow color. The color may be varied from golden yellow to yellowish brown by gamboge, dragon's blood and asphaltum.
The proportion of the different ingredients vary between:
|
Parts |
Dammar |
100 |
Boiled linseed oil |
50 to 120 |
Spirits of gum turpentine |
200 to 500 |
The dammar is pulverised and dissolved in hot spirits of turpentine, and boiled linseed oil or linseed oil to which a liquid drier has been added is run into the solution.
If the harder kinds of dammar be used, they may be rendered more soluble in linseed oil by the addition of a small quantity of soft dammar.