Hello, I made a hair cream that I stored in a round plastic jar at room temperature and a week after making the cream, it swelled up in the jar, and when I opened the jar, it exploded and cream sprayed everywhere. I don’t understand how that happened, and how to not do it again. I was trying to look up the reason online but not sure if I even know where to start. I think it might have something to do with “hydrogen swelling” but not sure because this is the first time it has happened. I do have acidic ingredients in my cream. Was that the reason for the exploding cream? The ingredients do start off warm during the formulating process and then they eventually cool in the freezer. Was that the reason? Thank you for any help you can give to this self-taught chemist!
Without a list of ingredients, it is really impossible to say exactly what was happening. Many reactions can produce gasses that could accumulate to excessive pressures in an enclosed container. A very likely one would be a reaction between an acid and a carbonate, producing carbon dioxide.
As Mr. Cooke states, most commonly this would be an acid and a carbonate or bicarbonate.... but that is usually a rapid reaction. It is unusual that it would take a week. Hair creams and so on often are emulsions, so if acid and carbonate/bicarbonate are in different phases they may react more slowly. Any gas generating reaction could have this effect.
Steven and James are correct. But you would know if you introduced baking soda and acid, and it usually happens quickly, unless something impeded the interaction, like we do with encapsulation. Then again, it could simply be the pressures generated by warming a sealed container, which induced both liquid phase and gaseous/headspace expansion.
However, you didn't mention pasteurizing the water, or the components, although you mentioned hot processing (but you may only have hit the optimum temperature to help organisms grow). Yes, some organisms give off gases. You could have incorporated any one of a myriad of safe preservatives (preservatives aren't used to kill 'hordes' of living organisms, but mostly to keep any trace organisms from growing rampantly).
There is the Annual National meeting of the Society of Cosmetic Chemists December 17&18 in NYNY, where you can meet and talk with some of the top minds in Personal Care Innovation. There is a special rate this year to attend just the technical posters, and talk with the authors (showing techniques, technology, or new functional ingredients). www.scconline.org and register for the Technology Showcase (or the entire meeting). See you there. Yes, the SCC also offers 1 and 2-day classes on specific topics. Or, on the same website, there is a resource tab that gives you the name of Consultants from various backgrounds, hair, skin, preservatives, patents, biofunctionals etc. Or, you can look up preservatives at https://www.ashland.com/selectors/preservative-selector you can always catch me after the new year at firstname.lastname@example.org
This is a better question for a microbiologist. If you did not use an in can preservative, I am almost certain that your concoction suffered an infection.