Sunday, May 9, 2010

How to duplicate a product!

I love figuring out what's in a product and duplicating it! I'll give you an idea of how I figure out how much is in a product when I set out to replicate it. It's based on what I know are the usage rates of the ingredients and where they end up on the ingredient list, as well as the skin feel. 

Ingredient lists are supposed to be written in descending order with the ingredient in the largest percentage first and the smallest percentages last. But in some cases, they're allowed to list everything under 1% in whatever order they like (I consider this the "miscellaneous" category). I know preservatives are generally used at lower than 1%, so I generally figure that's where the 1% list starts. I know other ingredients, like fragrance, gelling ingredients, fancy additives, or botanical extracts are used at 1%, so that's another indication of where I can start the 1% list.

Sometimes they fool me, though. Although I wouldn't use aloe vera at 1%, if it's only there for label appeal it could end up in the miscellaneous category. If you see it in the lower half of the ingredient list, near the preservative, then you know there's not enough to be beneficial. 

If we look at this ingredient list (from Spectro Jel's cleanser, which we'll take a look at duplicating tomorrow)...
Aqua, Butylene Glycol, Glycerin, Hydroxypropyl Methocellulose, Polysorbate 20, Cetyl Alcohol (moisturizer), Hydrated Silica, PEG-12 Dimethicone, Diazolidinyl Urea, Carbomer, Triethanolamine, Sorbitan Oleate.
I know that we won't be using more than 1% of the diazolidinyl urea because that's the preservative, which means the carbomer and following ingredients will be 1% or less. I'm not sure about the PEG-12 dimethicone, so I will assume (for now) that's at more than 1%.

If I'm not sure about usage rates or purposes of certain ingredients - like the hydrated silica - I visit the site and look it up for information or search through my text books. I see from the Safe as Used PDF this ingredient can be used at up to 34% safely. But it's also used as an abrasive, and I don't remember this product being abrasive, so I'm assuming it's there as a gelling agent. I know that we wouldn't use tons of gelling agent, so I'm thinking it's around the 1% mark as well. If that's the case, then the PEG-12 dimethicone would be 1% or less in this product.

There's one thing stumping me in this recipe - the hydroxypropyl methylcellulose. I know it's a gelling agent and it can be used up to 3%. So if we assume the highest we'd go is 3%, this means everything below it is 3% or less. Which means I can use a starting point of less than 3% for the polysorbate 20 (which makes sense because it's a co-emulsifier with the sorbitan oleate), cetyl alcohol, hydrated silica, and PEG-12 dimethicone. This will also relate to the amount of carbomer I use. If I'm using another gelling agent - or two if the hydrated silica is also for gelling - I know I need to use less carbomer, thus less TEA.

So if I break it down I know that I have the following amounts...

  • water - whatever's left over
  • butylene glycol - not sure yet
  • glycerin - not sure yet 
  • hydroxypropyl methylcellulose - less than 3% 
  • polysorbate 20 - less than 3% 
  • cetyl alcohol - less than 3%, probably more than 1%
  • hydrated silica - less than 3%, could be less than 1%
  • PEG-12 dimethicone - less than 3%, could be less than 1%
  • Diazolidinyl Urea - 1% or lower
  • Carbomer - 1% or lower
  • Triethanolamine - 1% or lower
  • Sorbitan Oleate - 1% or lower

I hope I've given you some idea how to use your knowledge of your ingredients, usage rates, and skin feel to figure out how to duplicate your favourite recipes!


Mich said...

Thanks for letting us take a peek into your brain during "reverse engineering" mode!
You rock!

Sierra Snow Soaps said...

This is so helpful, I love it. My dd has an AP Bio test in the morning and we are going over some of her studies and I wanted to show her your site. As usual, awesome!
Michelle in NV

Anonymous said...

You're the Sherlock Holmes of the Cosmetic Science world! :)

Evik said...

Excellent, excellent! I am so happy to find this blog, please, keep writing! Good luck! Evik

Jizzy said...

Susan, I truly appreciate your blog. I'm an aspiring mixtress and your posts are like my bible. You've really taught me a lot. Keep up the great work!

Sherry D said...

This is amazing! You know so much already... I have to admit I am so intimidated by this. I feel like I have to get into chemistry and reactions to know anything about how these ingredients work or work together. Guess it's time for more research... I can't WAIT to start working on my own products. One question, though... do you recommend any particular tools to start off with? I noticed a woman on Youtube using beakers and some sort of little mini stove/heater system. Not sure if I should invest in some sort of set or just use the stove?

Susan Barclay-Nichols said...

Hi Sherry! I've answered your question as part of today's Weekend Wonderings. The short answer is that we should make or buy a double boiler for our projects as our ingredients can't take direct heat.

Lynn said...

I have some homemade anti-wrinkle cream that someone made and gave me. I would love to duplicate it so that I can make it at home. I only have a list of the ingredients she uses and was wondering if you could give me some direction as to where I could get help in using the correct amounts of each ingredient. The ingredients are as follows: rose water, apricot oil, avocado oil, beeswax, lanolin and neroli essential oil.

Thanks in advance for your help.

Susan Barclay-Nichols said...

Hi Lynn. Sorry, I don't offer help duplicating any more. Havng said that, you could find many versions of this recipe on the 'net. You will need to use the lanolin as an emulsifier as beeswax isn't an emulsifier.