Combining the Same INCI That Comes From Two Raw Materials

Glycerin is probably the single most common ingredient to accidentally list twice, or worse, list twice under two different quantities that don't add up to reality. It's cheap, it's in almost everything as a humectant, and it also shows up as a carrier or diluent inside other raw materials you might not think of as "containing glycerin" at all. If you've got a preservative blend and an extract that each bring their own glycerin along for the ride, your final ingredient list needs one line for glycerin, not two.

Why this happens so often

Most formulators add glycerin directly as a standalone ingredient because it's a good humectant. But glycerin is also a very common carrier for:

• Botanical extracts (a lot of glycerin-based extracts use it as the solvent)
• Some preservative blends, where it dilutes the active preservative components
• Certain colorant dispersions

So you might have 3% glycerin added directly, plus a botanical extract used at 2% where the extract itself is 50% glycerin by weight. That second contribution adds another 1% glycerin to your formula that's easy to miss if you're only looking at your own batch sheet and not tracing every raw material's internal composition.

Working the math

Take that example and work it through properly.

1. Direct glycerin addition: 3.0% of total formula
2. Botanical extract added at: 2.0% of total formula
3. That extract's glycerin content per its certificate of analysis: 50%
4. Glycerin contributed by the extract: 2.0% x 0.50 = 1.0%
5. Total glycerin in the finished product: 3.0% + 1.0% = 4.0%

The single line on your ingredient list should read Glycerin at 4.0%, or within whatever range you're declaring, not 3.0% in one place and a hidden extra 1% nobody accounted for.

Source	Contribution to formula	Glycerin content	Glycerin contributed
Direct addition	3.0%	100%	3.0%
Botanical extract	2.0%	50%	1.0%
Total			4.0%

Why the summed number matters

A concentration range or percentage on the Cosmetic Notification Form is supposed to reflect what's actually in the finished product, not just what you added on purpose. If a reviewer or anyone checking your filing later finds that the real glycerin content is higher than what's declared, because a supplier blend's contribution went untracked, that's a discrepancy that reflects on the accuracy of the whole notification, even though glycerin itself isn't a restricted ingredient in most cases.

This gets more consequential when the duplicated ingredient is something with an actual concentration limit attached, like a preservative or an acid. If dehydroacetic acid, benzyl alcohol, salicylic acid, or a similar restricted-concentration ingredient shows up from two different raw materials and only one contribution gets counted, you could end up filing a formula that looks compliant on paper while actually sitting over the real limit.

How to catch this before you file

1. List every raw material in your formula, including ones you think of as "just an extract" or "just a preservative."
2. Pull the certificate of analysis for each one and note its full INCI breakdown, not just the headline active ingredient.
3. Build a simple spreadsheet mapping each INCI name to every raw material that contributes it, multiplying use level by internal percentage for each.
4. Sum every INCI name that appears more than once before you write your final ingredient list.
5. Pay special attention to any duplicated ingredient that also carries a concentration limit.

Water is the ingredient people expect to see everywhere, listed as Aqua, but glycerin, benzyl alcohol, and citric acid are the quieter repeat offenders that slip through when a formulator is tracking their own added ingredients but not tracing what's already built into someone else's blend.

Cosmetic Comply does this expansion and summing automatically. When you enter your formula, including any supplier blends, it maps each component back to its INCI name and CAS number, multiplies through the percentages, and combines duplicate ingredients into one accurate line before screening the total against the applicable restricted and prohibited lists. That's the step most likely to get missed doing it by hand, and it's exactly where a small formula error can turn into an inaccurate notification.