Whitney Ryan > writes:
>Where can one buy food grade cornstarch &
>calcium phosphate?
>
>I bought a ton of Baking Soda at Costco
>(sodium bicarbonate), and I want to make
>a small amount of baking powder.
>
>Baking powder, as far as I can tell, is
>baking soda + cornstarch + "cream of tartar"
>which is usually either calcium phosphate
>or potassium hydrogen tartrate (KC4H5O6).
>
>I went to Safeway, Trader Joes, and Whole
>Foods, but none had the missing ingredients,
>only one of which is required (the cornstarch
>is optional but the acid tartrate is not.
>
>Where can one buy food grade cornstarch &
>calcium phosphate?
>
>Cream of Tartar

Every grocery store I've patronized carries
both "food grade cornstarch"[*] and cream of tartar.

Check the flour section for the former, and the
spice rack for the CoT.
[*] Used to work on the line bagging starch in 100#
bags. For food grade, we had to wear a hairnet.