Cream of Tartar 50g
Cream of Tartar (potassium bitartrate) is a mild acid whch is a product of grape fermentation. It is used to add acidity (decreases PH) to effect a colour change, and to soften wool fibre when mordanting with alum. Our cream of tartar is food grade.
It shifts the colours with cochineal and lac from fuschia and burgundy shades tobrighter and redder colours. With madder, it will shift the hue to orange. 
With logwood and some tannins, it inhibits colour development.