Highly insoluble copal resin, if first combined with oil, will mix easily with solvents and other resins to make varnishes and mediums. This is a formula we use with hard copal resin to make a wonderful painting varnish. For most painters, we do not recommend making it but it is presented here for its academic value.
Ingredients:
| 2 parts | copal resin (crushed, dried chunks) | |
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| 3 parts | Special Aged linseed oil |
- Be sure to have excellent ventilation because this can be smelly and smoky. Heat the oil to a high temperature in one pan while you melt the copal resin in another. If the oil is cooked for about 45 minutes it will thicken and darken, causing it to dry much more rapidly.
- After the resin melts pour the hot oil into it, stirring until all is combined.
- Let the mixture cool and pour it into a clean container. This solution is very thick.
How to use:
This solution is a staple ingredient for mixing with many resins, balsams, and oils to make paint mediums and varnishes. It imparts a slippery thixotropic character to oil paints and if diluted with turpentine, it can be used as an isolating varnish. A thin coat dries hard in two days. A thick coat requires up to nine days.
While this is interesting to do, the smell and dangers outweigh its usefulness to the painter. We offer our copal concentrate already made, without the fuss.
