Cream of tartar is a byproduct of the winemaking industry. During fermentation, a sediment forms on the inside of the barrels, containing tartaric acid. These are crystals of argolis, that are ground, purified, dried, and reground to produce cream of tartar.
Cream of tartar and sodium bicarbonate are used in combination to create baking powder, which was invented in 1854 in the United States and has had a long history of safe use. It is used in baking and in Lush products for the same reasons, to create aerated textures and mousses that hold well. In hair care treatments it will also enhance the effect of the natural ingredients, making them more powerful.
Combined with sodium laureth sulfate, the two materials make the base of the solid and self-preserving bubble bars. They form a versatile paste which can be used to make an endless variety of shapes and give fantastically frothy and dense bubbles.
Lush purchase this ingredient in Italy. It is made by a family-run business established in 1968, who collect the necessary sediments from several wine producers in the country. Experts in their field, they have opened five more production sites around the world over the past decades, although we still buy from their original location.