Hydroxyethylcellulose and CAPB
Last week I was at the lab formulating a very basic shampoo formulation with a client, using hydroxyethylcellulose (HEC), sodium laureth sulfate and cocamidopropyl betaine (CAPB).
The thing is, we noticed that the formulation was losing viscosity when we added the preservative at the end of the process (caprylyl glycol and phenoxyethanol blend solubilized in cocoamidopropyl betaine).
Our first bet was that HEC was incompatible with the preservative system. So we did a test adding other preservative that we had in the lab (without solubilizng in CAPB) and the viscosity loss didn’t happened. Then we did other test adding just CAPB at the end of the process, without the preservative system and the viscosity loss happened. So we thought that HEC was actually incompatible with CAPB, not the preservative system.
After that I did a quick research in the forum and saw some discussions saying that HEC is incompatible with surfactants. Is that correct? Is it incompatible with a certain percentage of active matter or just some specific classes (e.g glucosides, betaines)?
I also wanna conduct some tests here in the lab using other surfactants and other concentrations of active matter. When I get some results I’ll bring it here too.