Unexpected Chemical Reaction in Art!

My wife is an Early Childhood Educator. For art projects, it is common for her to mix Tempera paints with Elmer’s glue for colored glues. (Of course, now you can buy it, but you can make it yourself.) Anyhow, this time she mixed the paint with an unmarked white glue. Before she knew it, she had created “The Blob”! The mixture started “erupting” in slow motion doubling in volume and overflowing the container. A vinegar-like smell was noted. It is obvious the increase in volume was caused by the escaping gas.

It is suspected the glue was actually a decoupe glue. Does anyone know what happened here? - Jinx

The glue may be decouche glue? decoupe? Tomayto, Tomaahto!
(I can hear the French already cringing as some silly American slaughters their language! Sorry!) - Jinx

A bit of googling reveals many reference to “pH neutral” white glues, which leads me to suspect that some white glues are acidic. From the odor you mention, the culprit is probably acetic acid. Some tempera-like paints contain calcium carbonate which will react with the acid in the same foamy fashion as bicarbonate (baking soda) and vinegar.

I believe the name you are looking for is decoupage. :slight_smile:

Thanks, QED! That’s the ticket! :wink: - Jinx