I ran out of baking powder making a triple batch of waffles, so I did the well-established substitute: 1 part baking soda to 2 parts cream of tartar.
Example: 1/4 tsp baking soda to 1/2 tsp cream of tartar yields the equivilant of 1 tsp baking powder.

I saw some variants of this recipe which call for 1 part corn or potato starch as well.
Example: 1/4 tsp baking soda, 1/4 tsp starch, 1/2 tsp cream of tartar yields 1 tsp baking powder.

Does anyone know if the difference between these recipes is what making baking powder single or double action? I've looked in my cookbooks and on several places on the net, but I can't seem to find an answer to this. Does anyone know?

I don't know about double or single acting, but cornstarch is added to make the mixture smoother and keep it from clumping in storage. If you're making it as needed, you don't need to add the cornstarch.  

The difference between single and double acting: Single only leavens once, when liquid is added,  double leavens when liquid is added and again when heat hits it - like in the oven. I don't know, ingredient wise, what the difference is.  

Edey

Joyous:

Does anyone know if the difference between these recipes is what making baking powder single or double action? I've looked in my cookbooks and on several places on the net, but I can't seem to find an answer to this. Does anyone know?

I looked in my Meta Given's Modern Encyclopedia of cooking, copyrights 1945, 1955, 1959, 1966 & 1969, and on page 112 she writes the following. It is long, but thorough::

"Two different types of baking powder are commonly used in the home, both containing baking soda and cornstarch, plus certain acid reacting compounds which vary in nature and amount. The powders derive their names from the acid reaction ingredients. They are: 1) sulfate-phosphate, so called combination (or double-action) baking powder, containing soldium aluminum sulfate and calcium acid phosphate.  2) Tartrate baking powder, containing cream of tartar and tartaric acid, and phosphate baking pwder, containing calcium acid phosphate.  Since food laws in general require that the ingredients be named on the label, you can readily determine which type of baking powder you are using.

The leavening gas given off by both types is the same, but the rate of formation and residue varies considerably. Baking soda is the alkaline compound in baking powder which, in the presence of water, reasts with the acid ingredients of baking powder to form carbon dioxide, which is a gas.  In this reaction, the batter or dough is permeated with very fine bubbles of the gas which make the batter light.  The only function of the cornstarch is to keep the active chemical ingredients separated and inactive while in the container. It has been found that a major portion of the cornstarch formerly used in combination-type baking powders may be replaced with a specially precipitated calcium carbonate, which, not only keeps the baking powder stable but also has the health advantage of enriching baked foods with substantial amounts of much needed calcium.

The rate of gas foration differs according tothe type of baking powder.  Sulfate-phosphate (Combination-type) baking powders have their lesser action in the cold batter, with the greatest action in the oven.  That is why these baking powders can be sifted witht he dry ingredients.  Such batter or doughs, after being poured, or rolled out and cut, may stand a short time without much effect on the leavening power.  Tartrate and phosphate baking powders have the marjor portion of their action in the cold batter and the lesser action in the oven.  For this reason, these baking powders are sprinkled over cake or other batters the last minute of beating.  As soon as the beating is finished, the batter is promptly poured into the pans and is promptly placed in the oven."

As a child, my mother taught me to store the unopened can of double action baking powder upside down to minimize the loss of action due to ageing on the shelf.  Cans are supposed to be good for up to 2 years, kept in a cool dark area. She also taught me to shake the can with the lid in place before removing the lid to measure after the can was open, to keep the ingredients well mixed.  - Marivene

Wow! Thanks for typing all that out! So the starch has nothing to do with it. If it's cream of tartar, it's single action?

Joyous:

If it's cream of tartar, it's single action?

Hi Marivene,

It sounds as though, as long as you have the starch, that either single or double action baking powder can be stored. I'm concerned about the sodium aluminum sulfate in some powders - do you know what it does or why it's there? I might need to do some legwork on that, but if you happened to know, it's a lot easier for me to just ask!