Active Matter vs As-Supplied Percentage in Your Formula

Here's a mistake that looks small on paper and quietly throws off an entire ingredient declaration: treating a surfactant's "active matter" percentage as if it were the concentration you're adding to your formula. It's one of the most common gaps between a maker's working recipe and what should actually appear on a filing, and it usually isn't caught until someone checks the math line by line.

What "active matter" means on a spec sheet

Plenty of liquid raw materials, especially surfactants like sodium lauryl sulfate or sodium coco-sulfate, aren't sold as pure substance. They arrive as a solution, typically the active ingredient dissolved in water at some standard concentration, often something like 30% active matter. The rest of that liquid is water, sometimes with a small amount of a stabilizer or salt.

When your formula calls for "10% SLS" and your bottle is labeled 30% active matter, using 10% of the as-supplied liquid does not put 10% actual SLS into your product. It puts roughly 3% actual SLS into your product, because you're adding 10% of a liquid that's only 30% active.

The two numbers you need to keep separate

• As-supplied percentage: how much of the liquid raw material, exactly as it comes out of the drum or bottle, you're weighing into your batch.
• Active matter concentration: the real amount of the named substance in the finished product, after accounting for the dilution the supplier already built in.

For a filing, what matters is the active matter concentration in your finished product, because that's the actual ingredient identity and amount Health Canada or any other regulator wants declared, not the volume of diluted liquid you happened to measure out.

Doing the math correctly

The calculation is the same logic as expanding a supplier blend, multiply the concentration of the active substance in the raw material by how much of that raw material you added to the batch.

Real concentration = (active matter % of raw material) x (as-supplied % added to formula)

A worked example: your formula uses 12% of a surfactant supplied at 28% active matter.

0.28 x 12% = 3.36% actual surfactant in the finished product

That 3.36% is the number that goes on your ingredient declaration and any restricted-ingredient check, not 12%.

Raw material as supplied	Active matter %	As-supplied % in formula	Real concentration in product
Sodium Lauryl Sulfate solution	30%	10%	3.0%
Sodium Coco-Sulfate solution	40%	15%	6.0%
Cocamidopropyl Betaine solution	30%	6%	1.8%

Why this matters more than it seems

Two situations make this error genuinely consequential rather than just a rounding quibble.

First, restricted-ingredient limits are set against the real concentration in the finished product, not the as-supplied amount. If an ingredient carries a concentration cap on the Cosmetic Ingredient Hotlist and you evaluate your formula using the as-supplied percentage instead of the active matter percentage, you can either fail a check you'd actually pass, or worse, clear a check you should have failed, if the dilution runs the other direction on a different raw material.

Second, fragrance and preservative math often stacks on top of this same confusion. A preservative blend that's itself diluted in a carrier, added at an as-supplied percentage, needs the same two-step correction: the blend's own dilution, then the blend's use level in your formula.

Where to find the active matter number

This lives in the same place your other supplier documentation does, usually the technical data sheet or the safety data sheet. It's sometimes labeled "active matter," sometimes "active content," and sometimes just stated as a concentration in the product description, like "SLS, 30% aqueous solution." If you can't find it stated anywhere, ask the supplier directly before you build your formula math on an assumption.

A habit worth adopting

Whenever a raw material is described as a solution, a dispersion, or carries a percentage in its own name or spec sheet, stop and ask whether that percentage is the finished-product concentration or the supplier's own dilution. If it's the latter, run the multiplication before it goes anywhere near your ingredient declaration.

This exact category of error, real concentration versus as-supplied amount, is one of the things Cosmetic Comply checks automatically when it processes your ingredient list, since it pulls active matter data from supplier documentation and calculates the true finished-product percentage before anything is screened or filed.