Episode 36: Irina Tudor on Fragrance Science

Chemists Corner is a podcast about cosmetic science and formulating.

Today’s interview: Irina Tudor Irina Tudor

Irina Tudor is the founder and owner of Irina Tudor Consultancy. She has a Masters of of Science degree in Behavioral Science and has studied cosmetics through the SCS distance learning program. She is a researcher focusing on the science of odor and smell and is available to help solve fragrance problems.

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Twitter: SomethingSmelly


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Cosmetic Formulating Tips

This question was asked on the cosmetic science forum and I thought would make for a good discussion.

How do you go about switching ingredient vendors? We want to switch vendors because of lower prices and lower minimums. Can you just switch one ingredient out for another?

Why switch cosmetic ingredient sources

Before I answer, it is a good idea to think about why you would want to have an alternate source for a raw material. There are a number of reasons.

1. Price - You can get the raw material for lower cost. An excellent reason to switch suppliers.
2. Lower minimums - You can buy less of the ingredient. This is particularly important for small businesses.
3. Insurance - If you have a single source, you are at the mercy of your supplier. You should have other sources just in case something goes wrong.
4. Reliability - You need to have a supplier who will be able to reliably fill your orders.

Changing cosmetic raw materials sources

Unfortunately, changing from one source to another isn’t as simple as just buying from a new source. The main problem is that ingredients that have the same name, don’t necessarily have the same composition. INCI names cover a wide range of mixed materials. For example, Cetyl Alcohol from one supplier can have a higher % of C16 material than the Cetyl Alcohol from another supplier.

Another problem is that suppliers often make raw materials in a different way which can lead to different residual materials in the finished product. Residual materials are frequently hidden in a raw material but can wreck havoc on certain ingredients in your formula. The result will be a color change, viscosity change, or formula destabilization.

The bottom line is that you can’t just switch raw materials from one source to another without proper testing.

So how do you go about approving a different supplier?

To approve a new supplier there are a number of things you need to do. First, you need to make sure the specification (or specs) for the ingredient match. To do this, you can look at the certificate of analysis (C of A) that the new supplier provides with samples. Compare this document to your current specification sheet and note where there are differences. Then you can tell the new supplier changes in the specs that you can make. It may also be easier to just give the new supplier your specification sheet and ask that they meet it. Remember, specifications are negotiable.

Once you have matching specs for the new material, you’ll need to make batches and run some tests. The first test is simply to see what happens to your batch when you use the new raw material. Make a batch with your current raw material and make one with the new raw material. Keep all the other raw materials the same. Check the pH, viscosity, appearance, order, and anything else that might be different. You should also conduct performance tests. The specific test you conduct will depends on the type of product you are making. For cleansing products you would run a foam test. For skin lotions you might run a moisutization test. If things look good you’ll have to conduct stability tests of the formula in your final packaging. If the change is significant enough, for example this formula is a big seller for you, you’ll also want to run consumer tests. Once you are satisfied that you can’t tell any differences you can start using the new raw material.

Note, it may make sense to make a batch where you blend the new raw material with your current source just to make sure that you can safely blend the two ingredients in the future. Sometimes when you are making a batch you may run out of a raw material and be forced to use something from a different supplier.

Testing depends on material

There are some ingredients where it’s not too risky to use an alternate supplier. Things like Glycerin, Propylene Glycol, and Salt will be so similar that there is little risk in using a different source. But materials like natural ingredients, fatty alcohols, and surfactants are much more risky. For these you’ll want to do a full battery of tests.


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The job of a cosmetic chemist, or as they call it in the UK a cosmetic scientist, requires you to do a wide variety of things both in and out of the lab. Your main responsibility will be that of a formulator. This means you mix raw materials together to create cosmetic products like lipstick, nail polish, skin lotions, shampoos, toothpaste and any other type of personal care product.

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