Solid Sugar Scrubs

[Genny]

I'm doing a little experiment and I thought I'd share and maybe some people might have some ideas.

On May 1st I made one batch of solid MP sugar scrubs using the following ingredients:
3 oz MP base
2 oz coconut oil
6 oz white granulated sugar

That same day I also made a batch of CP sugar scrubs using the following ingredients:
3 oz 2 day old CP
2 oz coconut oil
6 oz white granulated sugar

Both were completely dry when I put them in their storage containers. Both were sitting on my bathroom counter. Once a week I'd open the containers, use my barely wet hand to touch one and then close it back up.

Well the last couple weeks have been very busy and I forgot to do anything with them. I went to check them and the mp one has some serious visible molding going on. The cp one has no visible molding going on.

I was told by the supplier of the mp base that solid sugar scrubs using mp base do not need preservatives because of the high alcohol content in the mp. So, I decided to test what they were saying.

So, anybody have any ideas on why the cp ones don't have visible mold yet?

P.S. I'll post pics of my experiment tomorrow morning.

 

[Hazel]

Thanks for sharing your experiment. I have heard CO has antimicrobial, anti-fungal and antibacterial properties. But since you used it in both scrubs, I don't know why one would develop mold and the other one didn't. What are the ingredients in the MP compared to your CP?

 

[Genny]

The MP base is the detergent free ones from WSP :Sodium Cocoate, Glycerin, Propylene Glycol, Water, Sorbitol, Sodium Stearate.

My cp: olive oil, coconut oil, soybean oil, water, avocado oil, lye, shea butter and castor oil.

I'm wondering if it's because my cp was only 2 days old and most likely still had active lye in it when I made the cp scrubs. :?:

 

[Hazel]

That might be since the lye may have made the pH too high for mold. But then I think eventually the CP scrub might mold. Perhaps the sorbitol might have also contributed to the faster growth of mold since it is a humectant. But I really don't know. I just guessing.

 

[Genny]

Well, I went to take a pic of the moldy scrubs but my husband apparently used up the batteries on it and "forgot" to replace them :roll: So, I'll have to post pics after I get new batteries.

But it's definitely mold. Just something for people to keep in mind that have also been told that MP has too high alcohol for mold growth.

 

[Lindy]

I agree with Hazel that the high Ph of the CP one does not maintain an environment for mold and bacteria to form. It's the reason why you don't need a preservative even with cream soap - the ph is high enough to protect the product.

Great experiment!

 

[Hazel]

I agree with Hazel that the high Ph of the CP one does not maintain an environment for mold and bacteria to form. It's the reason why you don't need a preservative even with cream soap - the ph is high enough to protect the product.

But will the CP stay mold free? Genny thought it might have been because there was still some active lye. But that would have eventually been used up and the CP will become milder as it cured. I don't know if the pH will lower by very much but I do think it might reduce slightly. I also thought MP would have a high pH since it is soap, too. Unless it's the addition of the glycerin in the MP. Someone once mentioned she had problems with mold growing on a bath product she made (bubble bars?). I'm not sure but I do remember she said she didn't have a mold problem after she eliminated glycerin from the recipe.

@Genny

Please let us know how the CP scrub turns out. I'm curious because I have some CP sugar scrub I made months ago. But I always pinch off a little with dry hands and take the piece into the shower.

 

[Lindy]

The CP should remain mold free. There are always going to the exception to the rule but if you look at the science the pH of soap remains high unless you're doing something actively to reduce it such as rebatching using baking soda. I don't know how much sugar it would take to get it to a point that it would be able to mold.

If you're making a sugar scrub with just oils, MP or other things like that then you need to preserve, but CP soap is basically salt and glycerin, salt is often used to preserve things and in the old days it was used to preserve meat through the winter..... so that's where part of my theory comes from. Does that make sense?

 

[Genny]

Lindy ~ Your theory does make sense.

So far the cp ones are still free from visible mold.

 

[new12soap]

When I was recently looking at different colorants I learned that some are only suitable for MP and others for CP, the reason being the difference in ph levels between the two. CP is considered "high ph" and MP is "low". I am also only guessing, but it would stand to reason that the higher ph of CP would inhibit mold growth in the scrub the way it does in soap. The alcohol in MP I would think will evaporate out over time and besides alcohol doesn't kill everything. JM2C

 

[new12soap]

I know this thread is a few months old, but I just made some sugar scrub cubes with M&P and I was wondering if you could give an update? Did the CP scrub hold up?

 

[Genny]

Yep, the CP ones are still fine. I'm going to keep them for a year to see what happens. The MP ones ended up growing so much mold that I threw them away.

 

[new12soap]

WOW. Okay, well... I told the people to whom I sent them to take one out of the container with a DRY hand before getting in the shower, and to be careful not to leave any moisture in the container. Hope they believe me and use them up quick!

Thanks so much for the update

 

[Genny]

I think individually wrapping the scrubs might really help in keeping them from coming into contact with water and germs from our hands. I know all that excess packaging is not the most enjoyable thing to think about, but either is moldy sugar scrubs.

I'm thinking I may do that with those cute candy foil wrappers.