Making Dammar Varnish — The Clear Picture Varnish for Oil Paintings

Select clean, pale, translucent dammar resin tears — avoid dark, cloudy, or bark-contaminated pieces as these produce a darker, less clear varnish. Place 100 g of resin tears in a cloth bag (muslin or cotton) and crush with a hammer or mortar and pestle to pieces roughly 5-10 mm. Smaller pieces dissolve faster. Dammar resin is brittle and shatters easily. Do not grind to powder — fine dust creates a cloudy suspension that is harder to strain clear.

Place the crushed resin in a clean glass jar and add 200 ml of pure gum turpentine (NOT mineral turpentine/white spirit, which dissolves dammar poorly). The standard ratio is 1 part resin to 2 parts turpentine by weight — this produces a medium-consistency varnish. Stir gently, seal the jar, and let stand at room temperature. Stir or shake gently every few hours. The resin will dissolve completely within 12-24 hours. Do NOT heat to speed dissolution — heat degrades the resin and increases yellowing. Work in a well-ventilated area as turpentine vapour is an irritant.

Once the resin has fully dissolved, strain the varnish through two layers of fine-weave muslin cloth stretched over a clean glass jar. The straining removes bark fragments, undissolved resin particles, and any insoluble impurities. For the clearest varnish, strain a second time through fresh muslin. The strained varnish should be a clear, pale golden liquid — nearly water-clear for the best grade dammar. If the varnish appears cloudy, let it settle for a few days and decant the clear portion from any sediment.

Dip a clean brush into the varnish and brush a thin coat onto a piece of glass or a test painting. The varnish should flow smoothly, level without brush marks, and dry to a clear, glossy film within 15-30 minutes. If too thick (sticky, leaves brush marks), add turpentine in small amounts and stir. If too thin (runs and drips, dries with no sheen), let the jar sit uncovered for a few hours to evaporate some turpentine, then re-test. A well-made dammar varnish dries to a perfectly clear, hard, glossy film that saturates the underlying paint colours beautifully.

Store the finished dammar varnish in a tightly sealed glass jar away from heat, light, and moisture. Dammar varnish has a long shelf life — months to years if properly sealed. To apply as picture varnish: ensure the oil painting is fully dry (at least 6-12 months for thick oil paint). Lay the painting flat, apply a thin, even coat with a wide, soft brush in long, parallel strokes. Do not rework or go over the same area — this causes streaks as the varnish begins to set. One thin coat is usually sufficient. The varnish can also be mixed 1:1 with turpentine for a thinner 'retouch varnish' used between painting sessions to restore colour saturation in sunken areas.