Questions: Preserving scrubs

Just so you know, this scrub uses melt & pour soap and is from this challenge (click for the post to find the recipes) as Petra and I tried to duplicate a Lush product. I used this mold from Voyageur - click here - one I use for a lot of things!

In this post, Deborah asks: I'm gonna try this recipe shortly but I wanted to ask why you don't have a preservative in this. Is it because it is one time use only? Just checking cause I've never made one and I wanted to be on the safe side. Thank you in advance.

Great question, Deborah! You know, I think there should be a preservative in here, and you're welcome to add one if you wish (more about that in a moment).

We always say that we don't need to include a preservative in an anhydrous product (one without water) and this scrub bar doesn't contain water, therefore we can make it without a preservative. But there's a caveat to that sentence - unless the product is coming near water. A scrub bar not only comes near water, but it could be sitting in a small pool of water if you leave it in an undrained soap holding container, so it's a good idea to put a preservative into it.

I generally make my bars to be used in two, maybe three, showers and I make sure they're stored in a well drained place, so I haven't worried about the preservation that much, but I think I was wrong.  I think it's better to include a preservative in the mix to be on the safe side because I don't know how long other people might keep the bar and how they might treat it. If I really don't need a preservative, then I'm adding 0.5% to 1% of something to a bar other people might consider unnecessary. If I do need it, then I'll be happy I included it!

In this post, an anonymous questioner writes: This may be a dumb question - I have never made lotions or scrubs before - I am learning all about this stuff now :) Would using Germall Plus as a preservative instead of Phenonip result in any difference in the final product? I am assuming these are just personal preference in preservative types.

Again, another great question! (I would say there are very few dumb questions, and ones about preserving our products are never ever dumb! You can never be too safe.)

You can't use liquid Germall Plus in an anhydrous or oil only product as it is a water soluble preservative. If you click here and look at the preservative chart, you'll see that Phenonip works for oil soluble products, as do the Liquipar preservatives. (There may be other preservatives out there that work for oil soluble products, but I haven't encountered them and haven't reviewed them on the blog.) The parabens are mostly oil soluble, which is why they work in scrubs or scrub bars.

If you wish to put preservatives into your scrub bars, emulsified scrubs, or oil based scrubs, follow the manufacturer's directions for usage. In the case of Phenonip, you can add it to the heated oil phase of your product.

But how much to use? A 200 gram product might have 100 grams of oil and 100 grams of sugar/salt/pumice so should you preserve it all or just the oil based ingredients? I choose go by the weight of the entire product - so oil and salts and so on - at the percentage allowed by the manufacturer (for Phenonip, that would be 1%).

As a note, I will be revising my scrub recipes to include a link to this post! Great questions! 

If you're interested in learning more about preserving sugar scrubs or want to know more about water activity and preserving (which is the argument some people use in not preserving emulsified or oil based scrubs), please click here.