Saturday, January 26, 2013

Question: Are the preservatives found in our ingredients enough to preserve the product?

I see people asking if they need to include a preservative in their product when they are using ingredients that already contain preservatives, and the short answer is yes. The long answer is also yes with an explanation.

Let's say you want to make this toner (from this post on dry skin toners). How much preservative would we find in the ingredients? Is that enough to preserve the entire product?

MAXED OUT TONER FOR DRY SKIN
HEATED WATER PHASE
19% water
20% aloe vera
20% hydrosol of choice
20% another hydrosol of choice
0.5% allantoin
5% Cromollient SCE or water soluble shea or water soluble olive oil (PEG-7 olivate) or another water soluble emollient
2% hydrolyzed oat protein
2% hydrolyzed silk protein
2.5% sodium lactate or sodium PCA
2% niacinamide

COOL DOWN PHASE
2% panthenol
0.5% green tea extract
0.5% chamomile extract
0.5% banana extract (or another extract of choice)
3% honeyquat
0.5% preservative of choice (use as directed)

We will probably find preservatives in the aloe vera, hydrosols, proteins, sodium lactate, honeyquat, panthenol, and liquid extracts. They will be at the level required for that ingredient, which could range from the minimum to the maximum of the suggested preservative depending upon the difficulty in preserving that ingredient. Manufacturers are only going to use what they need in their product to save money, which means the preservative will likely be found in quite low quantities and might be specific only to that ingredient's needs without being a broad spectrum preservative.

What does this mean for us? If we relied only on the preservatives in our ingredients, we'd be short preservative for the product because our water isn't preserved! We don't know if the preservative used in an ingredient is suitable for the product we're making - for instance, is a surfactant as hard to preserve as a botanical? - and we don't know if we have enough. We also don't know if the preservatives are heat tolerant. I'm heating up a whole bunch of ingredients here, and most of our preservatives don't like to be heated and held, so how can I know if they survived the very necessary heated water phase intact?

In short, the preservatives found in our ingredients are not enough to preserve an entire product.

3 comments:

Lise M Andersen said...

Great post Susan. This is a question I also get quite often from folks.

Rocio said...

Hi Susan.

Thanks for sharing this information.

Have a great day!!

addictedtomakeup said...

Hi Susan, firstly I love your blog and as a formulator I've found it an incredibly useful resource. Having initially focussed on anydrous skincare products, I want to move into emulsions. When making creams for myself I have always used dehydroacetic acid / benzyl alcohol at 1% which I thought was sufficiently broad spectrum to cover everything. I recently read that it was weak on mould however, and that I should add 0.5% sodium benzoate to cover this. My question is: with the addition of the sodium benzoate, is it necessary to adjust the pH for this and if so, within what range? If I do, I have anhydrous citric acid to bring down the pH - but how do I incorporate this at cool down - can it simply be stirred into the cream or does it need to be pre-mixed with a little water? Thank you in advance! Natasha