Can you use baking soda instead of borax when making putty?

Although baking soda (sodium bicarbonate) and borax (sodium tetraborate) share some similarities, including being white powders and having sodium ions, they are different substances with distinct chemical properties. While both can be used in various cleaning applications, they are not interchangeable in all cases, especially when making putty.

In the context of making putty, borax plays a crucial role in cross-linking the polymer chains of the glue (typically polyvinyl acetate, also known as white glue) through a chemical reaction called cross-linking. This reaction creates a strong, flexible, and cohesive putty-like material. Baking soda, on the other hand, does not possess the same cross-linking properties as borax and cannot effectively substitute for it in putty making.

Borax reacts with the polyvinyl acetate glue to form a borate complex that acts as a cross-linking agent. This complex essentially "binds" the individual polymer chains together, creating a network of bonds that gives putty its characteristic properties. Baking soda, lacking this cross-linking ability, cannot provide the necessary structural integrity and elasticity required for putty.

While baking soda may have other uses in household cleaning, its inability to cross-link polymers makes it unsuitable as a substitute for borax in putty making. Substituting baking soda for borax will result in a mixture that lacks the desired putty-like properties, potentially leading to a weak, crumbly, or ineffective substance.

Therefore, if you are looking to make putty, it is essential to use borax as specified in the recipe and avoid replacing it with baking soda.