Homemade baking Powder

Did you know there was such a thing;)I find it hard to find baking powder without AL in it and found this recipe. credit goes to Edna Lewis. It works great, I just made my second batch of it today.

To make 1/2 cup baking powder, sift 1/4 cup cream of tartar, 2 tbsp. baking soda, and 1 tbsp. corn starch together 3 times. Transfer to a clean, tight-sealing jar. Store at room temperature, away from sunlight, for up to 6 weeks.