[jsbaldwin89]

I'm working on a project that requires me to mix a liquid solution that contains ammonia which is used as a surfactant together with dental stone which is a high grade gypsum used for making dental models.

The problem I get when mixing this solution with the dental stone is that it produces a lot of air bubbles in the stone. If I use just plain water, there are no bubbles.

I know that it's the ammonia that is doing this because I tried it with just water and ammonia and I got the same air bubbles in the stone.

I tried different brand dental stones and they all got the air bubbles when mixed with the solution that contains ammonia so the ammonia is reacting to a common ingredient in the stone. I'm not sure what else is in the dental stone besides gypsum and calcium. Whatever is in it, there is a chemical reaction causing the air bubbles.

The ammonia is part of the liquid solution so I can't remove it. Do you have any suggestion on how I can neutralize the bubbles?

Please feel free to re-post anywhere else where I can get help. Thanks for your *delete me*

James

[Borek]

One of the reasons I can think of is that setting of the gypsum means water is consumed, when water is consumed, concentration of ammonia goes up till solution gets saturated, then bubbles are unavoidable. If that's the case, I doubt there is anything you can do.

Then gypsum may be alkalic for some reason, which will force ammonia out from the solution - same problem as above, although slightly different mechanism.

You may try to lower pH adding acid - but then ammonia will be turned into NH₄⁺, which is a completely different substance, so it will probably change solution properties. Ammonia is usually used to make sure solution is midly alkalic.