Barrier forming agents (Hydrolyzed proteins, dimethicone ++) - Do they work?

Zink

So I see a lot of skin care lotion formulas add different types and size of hydrolyzed protein (from large like oats and wheat to small like silk protein), then there is dimethicone which is prevalent in several formulas.

Do these agents actually do anything? Is there much point to forming a "barrier" layer on the skin? What would such a barrier do? I like the idea of "locking in" moisture, but not sure what's hype and what's not.

If there are any natural (ish) agents that will effectively keep the skin moist for longer, let me know!

MakingSkincare

Zink - barriers/occlusives help reduce TEWL.  

More info and list of ingredients - http://swiftcraftymonkey.blogspot.co.uk/2010/03/chemistry-of-skin-trans-epidermal-water.html

Perry

Right.  Barrier ingredients are occlusive agents.  Some work better than others.  Petrolatum is one of the best.  Dimethicone is pretty good too.  That's why these ingredients are used.

mikebavington

The two most popular are petrolatum and mineral oil. They do, indeed, work.

Zink

So work in this context is measured by reduction of TEWL I assume.

Any studies on it with metrics on efficacy? E.g. what do vegetable oils do compared to mineral oils? What about hydrolyzed proteins? And good "natural" alternatives to dimethicone? Not using Zinc in this case.

pma

A bit of topic, but my favorite occlusive ingredient is lanolin. I know some studies show petrolatum prevents TEWL even better than lanolin, but according to my personal experience lanolin is much better than petrolatum.

It's sad and unfair this ingredient (lanolin) has a bad  reputation - even Kligman said it's a "false allergenic". But even formulators are afraid of lanolin. 

Bobzchemist

It's not just the allergenicity - most anti-animal-cruelty organizations consider lanolin an animal product and just as bad as using tallow or lard. Some people in the natural products industry even claim that the use of any animal product, including lanolin and/or beeswax, automatically disqualifies a product from being called "natural" (to them, nothing can be natural unless it comes from a plant).

Personally, I don't understand it. To get lanolin, you just collect it from wool. The sheep aren't harmed, and I don't see PETA going after the wool clothing industry.

It's the same with beeswax. Nobody kills bees to get beeswax, and bees are insects, so, rationally, how is beeswax an animal product?

Unfortunately, there is no reasoning with these people.

Bobzchemist

@Zink,

The skin is a pretty good barrier, and water doesn't really penetrate. Water and water vapor does, however, go out (TEWL)

If you think about it, though, there is much, much more water on the inside of our bodies than on the outside. Keeping that water inside the skin (reducing TEWL) is really the only effective way of moisturizing.

Perry

As a biology major I have no problem seeing Bees as animals.

But I agree, animal products like Lanolin, honey and Beeswax should not be a problem in cosmetics.  No animals are harmed in getting them.

Zink

What about  vegetable oils? How to do a "natural" friendly barrier? Could butters like shea work?

Perry

I looked for some published research on those but couldn't find anything.  Here is a relevant one on various oils and TEWL though.  http://journal.scconline.org//pdf/cc1979/cc030n06/p00345-p00356.pdf 

I doubt that vegetable oils would be occlusive enough to provide much benefit.  Shea butter may be better as it has longer chain fatty acids but not as good as petrolatum.

Zink

No vegetable oils there, searched and couldn't find anything either, but seems like people are pretty happy with anhydrous moisturizers.