Saturday, August 20, 2011
Using Preservatives in Your Handmade Bath & Body Products
I love handmade bath and body products. Even though I make them myself, I often indulge in the delights that other soapers come up with as well, because handmade carries the personality of the creator. Sometimes, I want the soap of someone with a sweeter personality than mine. Or just someone who doesn't swear like a biker. So I do cruise the interwebs looking for awesome stuff, and I find it, yay! But in the search, I find OTHER THINGS too.
I've already posted here about the super hippie preservative free lotions available. All natural means bacteria and fungus. They're natural too, but I don't want that much nature in my lotions. I love a little preservative. I said a LITTLE!
That's what this post is about. Overuse of preservatives. I have a list here, with the most common preservatives, their INCI names, usage rates, and effective pH range:
Optiphen - Phenoxyethanol (and) Caprylyl Glycol, 0.5%-1.5%, no pH restrictions
Phenonip - Phenoxyethanol (and) Methylparaben (and) Ethylparaben (and) Butylparaben (and) Propylparaben (and) Isobutylparaben, 0.5%-1.0%, pH 3.0-8.0
Germall Plus Liquid - Propylene Glycol (and) Diazolidinyl Urea (and) Iodopropynyl Butylcarbamate, 0.1%-0.5%, pH 3.0-8.0
Germaben II- Propylene Glycol (and) Diazolidinyl Urea (and) Methylparaben (and) Propylparaben, 0.3%-1.0%, pH 3.0-7.0
Tinosan SDC - Silver Citrate and Citric Acid, 0.1%-0.5%, pH less than 7.0, this preservative should be used with Potassium Sorbate to prevent growth of fungus.
Potassium Sorbate - Potassium Sorbate, 0.1%-0.5%, pH less than 6.0, not a broad spectrum preservative, most effective against fungus.
When reading the MSDS and Technical Data Sheets on these preservatives, one thing that really jumped out at me was a recurring phrase: wear protective equipment, including respirator, goggles, and gloves. Why? Because all of these, for lack of a better term, are poisons, and they kill bacteria and/or fungi. In large enough quantities (which for some of these is not very large), they can harm you too. And if used to excess in products applied to the skin, they can cause irritation and rashes.
What has me a bit worried, is that I see products with the preservative listed higher in the ingredient list than fragrance. This is a problem because in a best case scenario, the manufacturer doesn't know that you should list ingredients in order, by weight, from highest percentage to lowest. In a worst case scenario, it's a terrible problem, the manufacturer is using more preservative than fragrance. Now, fragrances and essential oils used as fragrance have varying rates of safe usage, but typically, that rate is anywhere from 3-10%. Some are even safe at 100% concentration, like anise, cedarwood, and fennel essential oils.
Anyhow, the preservative amount is so tiny, it should always be the last ingredient on your list. Tiny, tiny, tiny. Usually less than 1%. Never, ever as much as 2%, which is what one body butter I saw tonight claimed to have. Two percent of a preservative that should be used at no more than 0.5%, and can be effectively used at 0.1%. So that body butter had 20 times the amount of preservative that was needed, and four times the amount that is safe. I know that math isn't everyone's forte, but it's important to have the math skills necessary to safely formulate B&B products if you sell them. To figure out the amount of preservative you need, if it's given in a percentage, you need to move the decimal point two places to the left to get the correct multiplier. If the percentage given is 0.5%, then your multiplier is 0.005, or in fractional form, 5/1000. Multiply the total amount of your recipe, let's say 1000 gm of water, 300 gm of oils, and 100 gm of emulsifier, by the multiplier. In this example:
(1000gm + 300gm + 100gm) * 0.005 = 1400gm * 0.005 = 7gm
Translated into ounces, that's 50 ounces of lotion, with .25 ounces of preservative. 1/4 ounce in 1-1/2 quarts.
Another option, is to make butters with no water, aloe, or other water bearing liquid - bacteria and fungus need it to grow, and can't grow without it.
And you can get a respirator at Home Depot or Grainger (for example) for about $30.00, and it's something that I highly recommend. Safety first!