Friday, June 8, 2012

A few questions I've seen this week...

In this post, anonymous asks: ...I'm also interested in knowing if butters containing no water need preservatives, I've read conflicting information that they do not.

Anhydrous products - those without water - do not need a preservative unless they are exposed to water. (Click here for more information!) You can use an anti-oxidant to slow down rancidity - something like Vitamin E, for instance - but you don't need a preservative.

I think it's great that you want to use a preservative, and I encourage it in all water containing products!

In this post, KD asks: I can't use fragrances, what do I replace the 1% with to keep 100%? The water or butters?

Always increase the water amount when you leave out an ingredient. If your total water phase is 60% and you want to take out 1% fragrance, you'd increase the water amount to 61%. If you increase anything in the oil phase - for instance, the butters - you have to increase the emulsifier, and that's just a whole bunch of calculations that might be kind of annoying. If we simply add the removed amount to the water phase, we do some simple adding! 

In this post on formulating sugar scrubs with soy bean oil, desperatesoapwife (aka Marion) writes, First, thank you for all your great info. So highly appreciated and you are funny, too. I made this scrub and love it. I used 10% regular cacao butter and 10% Shea and 20% stearic acid, had no cetyl alcohol. The only thing, 2 days later, I had little white chunks, I assume stearic acid, in my scrub, which doesn't bother me, but I was wondering, if you have an idea why? I heated everything up and was holding it for 20 minutes.

In the same post, Alli asks, Why do you need to heat and hold if you're not using water?

Great questions! To answer your question, Alli, it's to help all the ingredients melt properly. Stearic acid  has a melting point of 69˚C, so we need to heat and hold the recipe to ensure that it has time to melt. If we merely get to the point of having the ingredients melted - for instance, using a microwave - our ingredients might not be completely melted and integrated into the recipe. Even if we use cetyl alcohol  melting point around 49˚C - our butters contain a lot of stearic acid, so we need to get it up to about 70˚C and hold it to make sure that all the fatty acids in any ingredient melt properly. 

What might have happened with Marion's scrub? We have a number of different melting points in the butters and stearic acid in this recipe, so heating and holding is a good idea - which she did - but we need to think about how it cools as well. For a product that has this many butters and fatty acids, we need to cool it quickly to get all the different fatty acids to reach their solidification points quickly rather than slowly. Placing your container in the fridge or freezer will make the fatty acids solidify quicker than leaving it on the counter. (We do this when we temper our butter to avoid grains!) I'm not saying this is the only possible answer for Marion - please comment if you have some other ideas! - but I think it's the most likely answer. 

Keep the questions coming - they're so much fun to answer! 


Anonymous said...

Hi Susan, I have a question about glycerin. I have read that it can act as a preservative, but the amounts I've read where it's effective have been anything from 15-70%. I was wondering if I make a simple glycerin-water spray, with about 20% glycerin, if I need preservative or if the glycerin itself does the job. Also, if I add other things like wheat protein, panthenol, etc., would the glycerin act enough like a preservative for the whole mix?

Also, I was wondering if there might be any science to back up using a vinegar rinse? I agree that using baking soda to wash hair is a terrible idea, but I have found a vinegar rinse (after shampooing, before conditioning) invaluable. My hair is much smoother and more manageable. I have heard the acidity closes the cuticle, but am yet to see the scientific backup to this. One odd thing I found - I once accidentally did the vinegar rinse between the 1st and 2nd shampooing, and it made the 2nd shampooing impossible. I can't remember exactly how, just that the shampoo wouldn't 'go' through my hair somehow, and I wondered if the shampoo couldn't open up the cuticle after the rinse.

My question is, is this, or some other reason, at least theoretically possible? I use cheap white vinegar because I think using apple cider vinegar would be a waste of money, about 1 part vinegar to 10 parts water. I have also used very dilute citric acid and found the same positive effects.

Kim said...

Hii, thank you for posting all this information. I made my very first lotion, a few months ago, thanks to you! I used your double boiler method for the heating and holding of my water and oil phase but I just couldn't get a stable temperature, then it was to cold and then to hot. Or water from the big boiling pot came in my smaller pots. I've been thinking about how I could get a stable temperature for 20 minutes and the oven seems to work best for me. I first heat my water/oil phase to 70°c in the microwave and then put it in the oven for 20 minutes. This seem to work, but I'm not sure if the method is ok...

Do you have to heat and hold using the double boiler method?

Thanks in advance, Kim