Resin dissolved without heat and aged

**Greg J.** · July 13, 2012, 10:08 AM

[LEFT][COLOR=#000000][FONT=Verdana]Neil's Best Damar Varnish and one other has the phrase "... resin dissolved without heat in pure gum turpentine and aged one year." What is the value of dissolving without heat? In my (small) understanding, this would create a varnish that will cure more slowly than if heated. Also, what is the value of aging it one year?[/FONT][/COLOR][/LEFT]

**Greg J.** · July 18, 2012, 08:29 AM

Anyone know?

**George O'Hanlon** · July 19, 2012, 08:46 AM

Originally Posted by Greg J.

[LEFT][COLOR=#000000][FONT=Verdana]Neil's Best Damar Varnish and one other has the phrase "... resin dissolved without heat in pure gum turpentine and aged one year." What is the value of dissolving without heat? In my (small) understanding, this would create a varnish that will cure more slowly than if heated. Also, what is the value of aging it one year?[/FONT][/COLOR][/LEFT]

All natural resins are more susceptible to yellowing when exposed to heat and light, so preparing damar without is beneficial, although it will still continue to yellow. Aging damar varnish improves its handling characteristics, according Leslie Carlyle in a her paper on recreating 19th varnishes.

**Greg J.** · July 20, 2012, 03:16 AM

Thank you! I would never have guessed those things with my (limited) understanding of the chemistry involved. Rhetorical thought: I wonder if pre-exposing natural resins to heat then bleaching them would reduce the amount they would yellow over time.

**George O'Hanlon** · July 20, 2012, 04:13 PM

Originally Posted by Greg J.

Thank you! I would never have guessed those things with my (limited) understanding of the chemistry involved. Rhetorical thought: I wonder if pre-exposing natural resins to heat then bleaching them would reduce the amount they would yellow over time.

No, this would not but actually lead to more yellowing. The yellowing is quite different from that of drying oils.