[Heike]

ETcellphone, I’m sorry to let you wait. 

Urea inclines to hydrolysis when it is incorporated in a water solution. In this process the pH value increase, and this is a critical point for some preservatives. Some formulators prefer a combination of lactic acid with its salt sodium lactate. That will slow down the increase of the pH value. 

[Heike]

Please have a look to Urea; because of your water based formula it needs to be buffered to keep the ph stable. You can try a buffering system with sodium lactate and lactic acid. Sodium lactate is also a effective humectant which will show synergetic effects with glycerin.

Betaine is good in combination with glycerin because of reduce the tackiness of it. But have a look to the total amount of glycerin - like Jemolian recommends.

For barriere repair I will recommend an other kind of ingredients or an other product type. You may find effective barrier regulation with linolic acid (in natural oils, some are more oxidative stable like others) combined with phytosterols and hydrogenated phosphatidylcholine. It’s a little bit tricky to do this with acne pronouned skin - try to begin with a very low percentage dosage. You can formulate a hydro dispersion gel with low parts of lipids.

[Heike]

Hallo, I’m Heike. My main interest is developing cosmetic products conform to skin physiology. I started as a hobbyist many years ago, but in the last few years my work has turned more and more to a side job. I’m interested in learning and exchange my experience with others. Perhaps someone knows my (german) website »olionatura.de«. Regardless of that, I am happy to be here and I greet everyone warmly.