Saturday, January 25, 2014
Weekend Wonderings: Do we need to include a preservative in an anhydrous product?
In this post, I'm working on a few things, Renee asks: Could I get your thoughts (or feel free to refer me to a post) - I blend a beautiful facial serum with plant oils (rose hip, argan, avocado, etc. That's it - 100% plant oils… I need to think in terms of a preservative but I'd like something on the ecocert list (and I appreciate your prior thoughts on what is natural, what is 'organic', and the concept of minimally processed). I'm keen to stay as 'natural' as possible… but first priority is safety.
The purpose of preservatives is to prevent contamination by microbes, and microbes require water, therefore we only need to put preservatives into products that contain water or that might be exposed to water, like sugar or salt scrubs. If we don't have water, we don't worry about microbes, which means we don't need preservatives in those products.
For non-water containing or anhydrous products, we can add anti-oxidants, or ingredients that will retard the rancidity of our oils. The anti-oxidant we use most is Vitamin E, but there are other oil soluble anti-oxidants, like rosemary oleo extract (ROE). Adding an anti-oxidant to an anhydrous product will extend its shelf life.
various preservatives in a chart like this, you'll see that they are listed as "water soluble" or "oil soluble". If you have a water based product that uses only water soluble ingredients, you would use a preservative that is water soluble. If you have an oil soluble product, you can use an oil soluble preservative. If you have a product that has both a water phase and an oil phase - like a lotion or conditioner - then you can use a water soluble or oil soluble preservative.
For instance, for a toner, I would use something like liquid Germall Plus as it is water soluble. For a sugar scrub, I would use Phenonip as it is oil soluble. And for a lotion, I could use either of them.
Back to the very basics: What you need to know about making any product (part 1)
Back to the very basics: What you need to know about making any product (part 2)
Newbies section of the blog
Preservatives section of the blog
What contaminants can get into our products
How preservatives work
Water activity and sugar/salt scrubs
In the same post, Marjo asks: I currently have conditioning emulsifier hope maybe you play with that one, too. I am interested in pH adjusting with citric acid. Measuring must be done in cold phase but the acid has to be dissolved so i wonder what the best routine would be.
As a question, what is the INCI name of the conditioning emulsifier you have. I would bet that what you have is either Incroquat BTMS-25/Rita BTMS-225 or Incroquat BTMS-50 as these are the ones commonly called "conditioning emulsifiers" by our suppliers. If so, I've written extensively on all of them. Do a search or click on the links to the right hand side of the blog. (When I say I've written a lot, I mean it! I have at least 100 recipes on this blog using Incroquat BTMS-50!)
citric acid, check out this post on the topic. The cool down phase isn't that cold - 45˚C or 113˚C - so the citric acid will dissolve in the lotion properly. Please don't be adjusting pH levels without having something to measure the pH because you could make it too low and that isn't good for our skin.
Adjusting the pH of your products
In the same post, Birgitte asks: I made this shampoo from The Herbarie: (http://www.theherbarie.com/SMC-Taurate-Soft-Bubbles-Shampoo.html)
I used Hydrolyzed Oats instead of silk amino acids and LGP instead of Optiphen. It was wonderful straight off the bat, but then weird things started happening. I left the bottle in my cold bathroom and the shampoo turned from opaque to all white, and the viscosity turned to snot. If I held the bottle under warm water it returned to its 'natural state'. What causes this? The SMC Taurate or the GuarSilk? Is there a way to make products less susceptible to temperature?
Surfactants (and oils) have what is called a titer point or cloud point, which is the point at which they start to solidify. When we see a product like a shampoo, it is likely the clouding we see relates to some of the surfactants in the product solidifying. When it gets solid, it drops to the bottom and goes white. In a colder environment, the viscosity will change and probably feel thicker. Heating the product will make it flow better and allow the surfactants to return to the liquid state. This can happen with other ingredients like our thickeners - I know Crothix will do this when really really cold as does glycol distearate - but it's mostly an oil and surfactant thing.
Weekend Wondering:...Cloud point of a solid surfactant
The importance of temperature - an example
Heating, holding, freezing, and thawing our ingredients
Points of interest relating to temperature
Join me tomorrow for more Weekend Wonderings!