Sunday, August 4, 2013

Weekend Wonderings: Why so many emulsifiers in a commercial product, why we weigh essential oils, heating our phases, and creating a double boiler

In this post, Keisha asks: I've fallen in love with Laura Mercier's Ambre Vanilla Souffle and was trying to replicate it. Looking at the ingredients, it seems like they might have used two different emulsifiers (glyceryl stearate & peg-100; cetearyl alcohol & polysorbate 60.) I'm curious, why would someone use two different complete emulsifiers? I was able to get close enough to the texture and feel of the souffle just by using the glyceryl stearate & peg-100, and couldn't justify adding a 2nd emulsifier. Thoughts?

Water (Aqua), Caprylic/Capric Triglyceride, Glycerin, Fragrance (Parfum), C12-15 Alkyl Benzoate, Cetearyl Alcohol, Glyceryl Stearate, PEG-100 Stearate, Isocetyl Stearate, Myristyl Myristate, Vitis Vinifera (Grape) Seed Oil, Isododecane, Acrylamide/Sodium Acryloyldimethyltaurate Copolymer, Jojoba Esters, Butyrospermum Parkii (Shea) Butter, Caprylyl Glycol, Steareth-2, Phenoxyethanol, Isohexadecane, Oryza Sativa (Rice) Bran Oil, Polysorbate 60, Benzyl Alcohol, Polysorbate 80, Chlorphenesin, Xanthan Gum, Benzoic Acid, Disodium EDTA, Panthenol, Sorbic Acid, Aloe Barbadensis Leaf Juice Powder, Honey (Mel), Hydrolyzed Rice Protein, Sodium Hyaluronate, Tocopheryl Acetate, Aminomethyl Propanol, BHT, Ascorbyl Palmitate, Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate, Butylene Glycol, Prunus Amygdalus Dulcis (Sweet Almond) Protein, Retinyl Palmitate, Styrax Benzoin Resin Extract, Cinnamomum Zeylanicum Bark Extract, Coffea Arabica (Coffee) Seed Extract, Honey (Mel) Extract, Myristica Fragrans (Nutmeg) Extract, Theobroma Cacao (Cocoa) Extract, Vanilla Planifolia Fruit Extract, Benzyl Salicylate, Coumarin, Butylphenyl Methylpropional, Limonene. May Contain (+/-): CI 14700 (Red 4), CI 42090 (Blue 1), CI 19140 (Yellow 5), CI 15985 (Yellow 6).

If we look through this list, we can see quite a few things that show up in emulsifiers, might have an HLB emulsifier value, or might be solubilizers themselves - like cetearyl alcohol, glyceryl stearate, PEG-100 stearate, isocetyl stearate, polysorbate 60, and polysorbate 80 - but they might not be in here as an emulsifiers. For instance, cetearyl alcohol might show up in emulsifying wax, but it's used as a thickener and emollient as well. (That's what I use it for!) Or polysorbate 60 might be used to emulsify fragrance or essential oils into another oil and the manufacturer purchased it that way (so the INCI would be something like tea tree oil (and) polysorbate 80 (and) sunflower oil).

A lot of ingredients we see in products are part of a bigger ingredient. For instance, Incroquat BTMS-50 is Behentrimonium methosulfate (and) cetyl alcohol (and) butylene glycol, so when I add it to my product's ingredient list, I will list it as those three ingredients, not as Incroquat BTMS-50. The ingredients might not show up side by side if they aren't in similar amounts. If I use 6% BTMS-50, it means I have about 3% behentrimonium methosulfate, 1.5% cetyl alcohol, and 1.5% butylene glycol. If I have 2% white willow bark extract and 2.5% cetearyl alcohol, those things will separate the ingredients, so my list looks like this: water, behentrimonium methosulfate, cetearyl alcohol, white willow bark extract, cetyl alcohol, and butylene glycol - it doesn't look like I'm using Incroquat BTMS-50 at all. It's not to be tricky, but to list the ingredients in descending order of usage.

Or take something like Germaben II, a broad spectrum preservative. The INCI is propylene glycol, diazolidinyl urea, methylparaben, and propylparaben. These can be put in any order they want after the point in the ingredient list that is used at under 1%. So the manufacturer isn't using propylene glycol in the product, but is using an ingredient that contains propylene glycol. (You can see this in this product with the preservative spread across three lines in the paragraph of ingredients above. It looks like they're using a version of Optiphen Plus with some other anti-oxidants thrown in.

There might be two emulsifiers in here creating an HLB emulsifying system - I'm thinking as you are that it's the glyceryl stearate and PEG-100 stearate - with the others as emollients or solubilizers for other ingredients, or there might be more.

In this same post, Lise notes this about essential oils: I have worked with essential oils for a long time, and although they vary slightly in weight, I have never managed to measured out 1 ml as 40 drops. The highest drop amount I have ever gotten into 1 ml was 24, and the fewest was 20 drops to a ml. Just thought I'd mention it as essential oils need to be carefully dosed.

Thanks, Lise! This is why we measure everything by weight! It's simply more accurate. Essential oils are not just about fragrance, many have therapeutic properties

To those of you who worry you might be overstepping by answer questions posed by your fellow readers - stop worrying and comment! I can't know everything, and I love to hear about what you've learned and can share with others. The whole point of this blog is to provide accurate information about making bath and body products, and I don't want to be the only one providing that information! So please, share! 

In this same post, Karen asks: I wondering why my oil and water phases seem to be two completely different temperatures even though I am heating them in the same pot. This happened to me the other day too, the oil phase takes much longer to heat and never gets as hot as the water phase. Am I doing something wrong?

I don't know if you are heating the ingredients directly on a stove top or in a double boiler, but that aside, you aren't doing anything wrong. I find the oil takes longer to heat up, so I make sure I have it in a glass container instead of plastic as it conducts the heat better, and I make sure the water has boiled up before I add my containers. I've taken to measuring out the oil phase first, adding it to the double boiler, then measuring out all the stuff for the water phase because the oil phase always needs more time.

Anyone have some better suggestions than mine? Please share! 

As a reminder: Please for the love of all that is good and holy, use a double boiler. Our ingredients can spatter, boil, and burn when we heat them directly, which is one of the reasons I beg you not to use a microwave. I still bear the scars of microwaved lotion bars on my arms. (I make mistakes so you don't have to!) The water acts as an insulator to keep our temperatures relatively steady.

It's easy to make a double boiler on your stove. Heat a large-ish pot of water to boiling, then reduce the heat so it isn't even simmering. Put a rack at the bottom if you want. Put your heat proof containers into the pot with the handles hanging off the side to make them secure. Heat until you reach 70˚C and hold them at that temperature for 20 minutes. (This is why we call it "heat and hold".) Remove carefully and finish up the product.

That's it for another edition of Weekend Wonderings! Have a comment or question? Add to the post of your choice - please choose a relevant one - or visit the Weekend Wonderings question page and I'll do my best to answer it!


Keisha said...

Yay! Thanks for selecting my question!

Anonymous said...

How cool! Get back from vacation and see you have addressed my question. I will try your suggestions


Anonymous said...

What suggestions do you have for a rack? I tried to use a trivet, but I found out the hard way it wasn't made out of stainless steel and it rusted after one heating.
Love your Blog, Dan.

johnny somethingerman said...

For the double boil, I really like my beaker set. Depending on the size of the batch I can use the 1000 or 750ml beaker for the water phase, or 500 or 250 ml beaker for the oil. The nice thing for me is I can get my stick blender in the wide open beaker. When I make really big batches, I go for a candle making pitcher (about $10 US on amazon).

I've had bad experiences putting cold glass in a boiling pot, so I let the phases heat up with the water, but I do things a bit differently for each phase. The oil phase I monitor only with an IR thermometer, allowing the oil to hold the heat to keep it around 70C (usually it sits at about 85C) with the stove on the lowest possible setting. I think I could hold it lower if I used a pair of bamboo skewers broken to fit in the pot as pylons for the beaker to rest on, keeping it away from the pot-s direct heat transfer.

For the water phase I use a candy thermometer, and I constantly watch the temperature and adjust the burner to keep the temp at 75C +/-5. Again, if I used the babmoo skewers I'd probably have less trouble holding the temp steady.

Using this method I've never had a lotion fail (except the time I tried using cetearyl alcohol as my high HLB emulsifier in an emulsification system, bad idea!).

Anonymous said...

A little late to the party, but to shine some light on the question of why the oil takes longer to heat up than the water, the answer lies in Heat Capacity vs Thermal Conductivity.

Water has a higher Heat Capacity than the oil, which means that in terms of amount of heat, you need more heat to raise the temperature of water than you need to raise the temperature of the oil the same amount. Therefore, you would expect that the oil would heat up quicker than the water; however, this is not the only thing to consider.

This is where Thermal Conductivity becomes very important. Water has a much higher thermal conductivity than the oil. This means that heat is transferred from your water bath to the water phase much more efficiently than it is transferred to the oil. In the end, the difference in Thermal Conductivity is greater than the difference in heat capacity, which results in the oil being slower to reach the same temperature as the water, assuming you start with about the same amount of each phase.

There ya go! SCIENCE!!

Susan Barclay-Nichols said...

Lovely explanation, Anonymous. But I'll be forced to delete it if you don't add a name to it. Sorry, but that's my policy as explicitly stated on every page of the blog, and I'd be grateful if you could respect that. Thanks!