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C18-36 ACID.

Valuable CAS 135620-17-6 / CLEANSING, SURFACTANT - CLEANSING, SURFACTANT - EMULSIFYING

A high-purity blend of long-chain fatty acids that functions as a structural architect and protective sealant for the skin barrier. Its unique carbon chain length allows it to provide exceptional stability and a smooth, non-greasy finish in precision skincare formulations.

Occlusive Emollient Viscosity Controller Skin Conditioner Structural Binder

Science

This ingredient operates as a biomimetic occlusive, creating a hydrophobic crystalline lattice over the stratum corneum. By filling the interstitial gaps between corneocytes, it effectively minimizes transepidermal water loss (TEWL) while simultaneously reinforcing the structural integrity of the product matrix.


Research

High confidence
Effective range 1–22%
Optimal

10%

Key findings

  1. 01 Clinical evaluations conducted by the CIR indicate that long-chain fatty acids in this category are safe and effective at concentrations up to 22%, particularly in anhydrous stick formulations.
  2. 02 Case studies involving 10% concentrations highlighted the necessity for high-purity sourcing, as rare sensitization was observed in compromised skin (dermatitis) while remaining inert in healthy control subjects.

Transparency

Not commonly dusted
Min. effective
1%
Red flag below
0.5%

Because it is often used for its textural and structural properties, it is rarely 'dusted' for marketing purposes. However, concentrations below 1% may not provide the meaningful barrier protection or viscosity control required for therapeutic efficacy.


The Formula

Solubility
Oil
Optimal pH 4.5 – 8.5
0 7 14

Stability

Exhibits superior oxidative stability due to its saturated long-chain structure. It remains stable across a broad pH range in emulsions but is primarily used in anhydrous systems where pH is not a factor.

Synergies

  • Hydroxystearic Acid
  • Behenic Acid
  • Squalane
  • Ceramides

Conflicts

  • Strong oxidizing agents
  • Highly polar solvents
  • Strong bases (risk of saponification)

Safety

CIR Status
Safe as used
Max tested
22%
Pregnancy
Safe
Sensitization risk Low

Safe for cosmetic use when formulated to be non-irritating. Sensitization is extremely rare and typically only seen in individuals with pre-existing severe dermatitis.


Your Skin

Yes Normal
Yes Dry
No Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Valuable

An excellent, stable lipid component for reinforcing the skin barrier and optimizing the physical delivery of stick-based and rich cream formulations.


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