Wax hardeners there are many, but damar resin is magic. What makes Damar crystals so special is their very high refractive index. In germany damar resin is known as Cat’s eye resin. Damar resin is also prized for incense use. It is said to lift the spirit, combat sadness and melancholy, bringing light to the soul . This optical qualities of the crystals earned them the nickname Cat’s eye resin.
I will write specifically on the refractive properties of encaustic medium sometime in the future for sure, but for the time being I need just to mention that elements with higher Refractive Index (RI) are generally more brilliant than those with low RI, because more light is returned back out, instead of just passing through. Diamond for instance has a RI of about 2,4 and damar crystals about 1,5 (in the same range as glass).
The resin improves the workability of the wax by increasing its melting point. Damar resin gives the wax the varnish-like optical property of showing high saturated colors underneath it.
Damar is a clear pale yellow natural resin obtained by “sweated-out” of trees growing in rain forest areas.The tree is an object of worship for Buddhist and Hindus in India.
The name of the damar resin comes from the Indonesian island Damar, the larger island from the group of volcanic islands of the same name located between Australia, Indonesia and Papua New Guinea. in Europa Damar resin crystals come mainly from Malaysia and Indonesia, and are graded in 3 stages being number 1 the nearly transparent in color and then sorted by size from A (big crystals) to F (powder). Dirt, twigs, rocks, and other impurities are always present in the resin crystals.
Damar contains 62% resin, 23% dammarol acid and 2,5% of water. It is specially used in varnishing (*) due to its low molecular weight and viscosity and high refractive index, which makes the underlying colors high saturated. Since 1826 dammar resin is used as main ingredient of picture varnishes of oil and tempera painting.
Damar crystals start softening at about 90ºC and melts at completely at 180ºC. When we mix 1 part damar to 8 parts bees-wax, what we are really doing is combining to elements with different melting point: bees-wax 70ºC and damar resin 180ºC, increasing in a range of 10ºC the melting point of the encaustic medium. When we mix 2 parts damar to 9 parts bees-wax we are increasing it in a range of 20ºC.
But why do we want this? just to maintain wax-medium workability (viscosity) in cooler temperatures 60-80 ºC at which otherwise bees-wax would already be congealed (cloudy).
How does damar resin crystals alters the aging of the wax? Damar resin primary process of deterioration is auto-oxidation initiated by photochemical reactions . The yellowing process is only a secondary reaction. Damar resin can also bloom, (bloom is a white haze) normally happens when it dries under conditions of extreme humidity.
Damar resin has low toxicity but the resin power can cause allergies (!). In crystalline form damar resin can be stored indefinitely in an air tight container in a dry and dark area.
(*) Did you know? The “vernissage,”equivalent to today’s “private view” was a social event of the time. Painters would put a fresh varnish layer in their paintings just before the opening of the exhibition. This would give the appearance of being freshly completed.
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