Great question! There really isn't a limit, apart from not using so much that it becomes a big Jell-o-y mess. Having said that, I think that we can use too much, as you'll see in the next few examples.
If you look at this one, Velvet Care Lotion, you'll see that they're using 0.25% Ultrez 20 in the heated water phase, which seems like a tiny amount, but it is enough to give us that cushiony feeling we want.
This one, In-Shower Lotion, has 0.30% in the heated water phase, while this one, Party Time Shimmering Cream, has 0.40% in the heated water phase.
The lotions to which I've linked above suggest that the Ultrez 20 is sprinkled over the surface of the water phase, which is heated to 65˚C to 70˚C. The sodium hydroxide (neutralizer) is added after the two phases are combined, but when it's still hot.
So how much can we use? Here's what the company suggests...
Recommended polymer use level is formulation dependent. For surfactant-cleansing applications with low-to-moderate surfactant actives 0.8% to 1.0% is recommended. For use in emulsions and gels, 0.3 - 0.7% is recommended, depending on electrolyte content. Processing instructions are simple.
- Sprinkle polymer on surface of water and allow to self-wet.
- Begin gentle agitation.
- Keep agitation to a minimum (to avoid air entrapment) while adding remaining ingredients to formulation.
- Neutralize: can be pre- or post-neutralized (depending on the needs of the formulation).
How did I come up with those numbers for the TEA or lye? For this and much more, please check out this post on Ultrez 20!
So the short answer is that although there isn't really a limit to how much you can use, there's definitely a suggested usage rate of 0.3% to 0.7% for Ultrez 20.
I've just realized in writing this that I've never shared my formulas in which I've used Ultrez 20 and Sepimax ZEN in a lotion! I'll have to fix that soon!
please click here and see what it's all about.