Dammar

Dammar (or alternately spelled 'damar') is used in foods, as a clouding or glazing agent, and in incense, varnish and other products. Dammar varnish, made from dammar gum mixed with turpentine, was introduced as a picture varnish in 1826 [1]; commonly used in oil painting, both during the painting process and after the painting is finished.[2]

Dammar crystals are also dissolved in molten paraffin wax to make batik, to prevent the wax from cracking when it is drawn onto silk or rayon.

The name is a Malay word meaning ‘resin’ or ‘torch made from resin’.

Dammar is the most popular natural resin for making spirit varnish. This is imported ABC Grade gum from Indonesia. Add turpentine and you have golden clear concentrated dammar varnish. This is the most economical way to obtain dammar varnish. Dammar can be used as:

• A final picture varnish for oil and tempera paintings.

• A medium added to oil paint for transparent glossy glazes.

• An ingredient in encaustic medium.

• An ingredient to make egg yolk emulsion that can be thinned with water.

Source

Dammar gum is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus or Hopea. Most is produced by tapping trees; however, some is collected in fossilized form from the ground. The gum varies in color from clear to pale yellow, while the fossilized form is grey-brown. Dammar gum is a triterpenoid resin, containing a large number of triterpenes and their oxidation products. Many of them are low molecular weight compounds (dammarane, dammarenolic acid, oleanane, oleanonic acid, etc.), but dammar also contains a polymeric fraction, composed of polycadinene.

Grades

Dammar gum imported from Indonesia (also known as Batavian dammar) is scraped free of surface dirt and then sorted according to size by sieving into seven grades, but today is usually only available in several grades.

Grade A

This type of gum dammar is whiter than other grades and is younger when picked. It is the grade retained on a screen having 0.588 inch openings, smaller sizes being designated by letters to grade F, which passes through a 40 mesh screen.

Grade CD

Dammar CD is almost the same as Dammar ABC. Its size is smaller than that of Dammar ABC because it is picked when it is 2 weeks old.

Grade ABC

Similar to the previous grades, this dammar is the most common grade imported and is good quality and is harvested when it is 2–4 weeks old.

Specifications

Dammar Varnish

It is best to prepare dammar as a concentrated varnish to make it easier to dilute and use in different recipes. Thinning the concentrated varnish with additional turpentine makes a final picture or a retouch varnish.

To Make Dammar Concentrate:

1 500 ml (1-pint) container with lid (such as a 1-pint Ball Mason jar)
String—the length of about twice the height of the container
Unbleached cotton cloth, cheesecloth or similar fabric
250 g dammar crystals
250 ml (1 cup) pure gum spirits of turpentine

Directions

If necessary, break larger crystals into pieces smaller than 1 cm (1/2-inch) pieces.

Wrap the dammar crystals in the cloth to make a small bag and tie the ends together with the string. Pour the turpentine into the 1-pint container.

Place the bag of dammar into the container, leaving one end of the string outside the container. Wet the dammar thoroughly by stirring the bag inside the container.

Close the container. If the lid will not fit because of the string, put the string into the container, on top of the bag, and close it up again.

Stir the contents of the container a couple of times a day.

After several days, when the dammar crystals have dissolved, remove the bag and put the lid on the container. If any debris has settled to the bottom, you can decant the dammar varnish into another container.

You now have a fairly concentrated dammar varnish that should be a golden yellow (sometimes slightly turbid) solution.

To Prepare Dammar Varnish:

Add 550 ml of turpentine to the concentrated solution of dammar to make a 31% weight/volume (w/v) solution. For an explanation about weight/volume solutions, read the article Measuring Resins in Varnish and Medium Formulas.

To Prepare Dammar Retouch Varnish:

Add 2,250 ml of turpentine to the concentrated solution of dammar to make a 10% weight/volume (w/v) solution. You can also replace a small amount (up to 100ml) of turpentine with ethyl alcohol (ethanol) to hasten drying and to clarify the dammar and turpentine solution.

Reference

1. Brannt, William Theodore (1893) Varnishes, lacquers, printing inks and sealing-waxes: their raw materials and their manufacture. H. C. Baird & Company. p. 168.

2. Mayer, Ralph (1991) The Artist's Handbook of Materials and Techniques (5th ed.). Viking Adult.