From Kremer's gum tragacanth specification sheet:
Gum Tragacanth is the dried exudate produced from Astragalus gummifer, which grows particularly in Iran. Tragacanth has the food additive number E413 in Europe.
Solubility: in water to a soft, stiff, opalescent slime.
From the Karawan Trading Corporation:
Tragacanth is one of the oldest gums known and its use dates back to 5000 years ago. This plant is used in traditional Iranian medicine for improving the human immune system and alleviating side effects of other pharmaceuticals. It is much used for the suspension of heavy, insoluble powders to impact consistence to lozenges, being superior to Gum Arabic, also in making emulsions, mucilage, etc. It is also employed by manufactures for shifting calico, crape, etc.
The gum is obtained from the plant . The farmers start harvesting from May and finish in September. In the west of Iran, where the weather is colder, it lasts until October; the farmers call their harvesting seasons spring and autumn. According to our experience the viscosity level in spring harvest is higher than in the autumn. The roots of the plants are scored with a special knife. The dried gum then seeps from the cuts and is collected by hand. It is later sorted by colour into different qualities.
From my kitchen:
Yesterday's mix is thickening and still with blobs of gum. Tomorrow I'll wrap up the solution and just might start making pastels!