I do love playing with gels. I can thicken a toner, make an eye gel, create a new facial cleanser, formulate an after sun gel with aloe, and so on. Let's take a look at two ingredients I've been using a lot to make gels lately - Ultrez 20 and Sepimax ZEN.

ULTREZ 20 (INCI: Acrylates/C10-30 Alkyl Acrylate Crosspolymer) 
What is this exciting polymer that makes ooey gooey fun" From Lubrizol: "A self-wetting rheology modifier designed to impart moderate-to-high viscosity as well as stabilizing and suspending properties to personal care applications." In other words, it's a white powdery thingie that you add to water to create a gel that will thicken your creations.

Sounds awesome, but there's always a down side, eh" Gels don't tend to play well with electrolytes, cationics, or salts - three things we may want to include in our gels. Ingredients like aloe vera or sodium PCA contain a lot of electrolytes and salts. Cationic or positively charged ingredients are things like cationic polymers like polyquaternium 7 or honeyquat, as well as Incroquat BTMS-50 and some hydrolyzed proteins. (For instance, I know the silk amino acids from Voyageur Soap & Candle thins out Ultrez 20 thick gels.) As well, the final pH of a gel with Ultrez 20 should be around 4.5 to 5, so you can't add things like glycolic acid or AHAs easily.
Ultrez 20 notes that it can handle up to 10 to 12% surfactants, which isn't a lot, so this isn't the thing to thicken up a body wa...