-
Is urea heat sensitive?
I have always added urea to my water phase and this appeared to work well. Is urea heat sensitive? Should I be adding it during cool down?
-
6 Replies
-
It is not heat sensitive for short periods of time, Lindsay. It WILL however make an endothermic reaction when it hydrolyzes with water, so I always used that physical property to my advantage when making urea creams: emulsify, then add urea during cool-down so it will help the process along. Cool, huh? (Yes, pun was intended)
-
Thanks for your (cool) reply. Much appreciated.
-
What about allantoin? It probably is preferable to add it during cool down but I add it to the water phase because I feel I need the heat to get it dissolved properly (even at low %).
-
urea is heat sensitive in water solution. In general urea is not stable in water solution.
https://www.ncbi.nlm.nih.gov/pubmed/25043489 -
Many thanks for the link. Very interesting.
-
No worries: employ a lactate buffer at pH 5 - 6. Urea will always slowly hydrolyze to biuret, ammonium nitrate and eventually ammonia, but that goes with the territory, as everyone knows. Urea creams are one of the oldest “natural” product formulations in existence - nearly 100 years of use. They work well too.
Log in to reply.