WHAT ARE PEARLIZING AGENTS IN SHAMPOOS?

Also known as “opacifiers”, pearlizing agents are ingredients that make a shampoo solution appear less transparent and more rich and pearly.  They could be classified along with colorants, thickeners and fragrances, as cosmetics for the formula.  These are ingredients that give the shampoo a more desirable appearance.  Without cosmetics, most shampoos would be unattractive to the consumer.  With just the basic ingredients, most shampoo formulas would be watery, grayish and maybe a little cloudy.  Pearlizers give the solution a more luxurious, rich appearance.  Modifying the appearance of a solution is one of the skill sets of the cosmetic chemist, the formulator who designs the product.  Thickeners, opacifiers, colorants, and fragrances are crucial tools in the creation of an appealing shampoo product. 

The most common pearlizing agent in shampoos is Glycol Stearate, also known as Glycol Monostearate or Etheylene Glycol Monostearate (EGMS). Chemically, Glycol Stearate is the ester of ethylene glycol and stearic acid.  It is NOT a mixture of the two.  It is a distinct chemical compound.  Yes, it comes from ethylene glycol, but it does not contain ethylene glycol.  Stearic Acid is a widely used fatty acid that can be derived from either plant or animal sources.  This allows it to be claimed as a “naturally derived” substance.  While some shampoo manufacturers might want to extend this definition to Glycol Stearate, this is a stretch.  It is my opinion that this is clearly a chemically engineered ingredient.  This fact does not make it undesirable.

 PROPERTIES OF GLYCOL STEARATE.  Like many ingredients in the tool box of the cosmetic formulator, Glycol Stearate usually serves more than one function in a product.  It has several desirable properties.

• Opacifying agent – Used in small amounts, glycol Stearate has the ability to make liquids less transparent.  It’s light reflective property makes the solution shimmery or pearly, giving it a luxurious appearance.  Used at 4-5%, in a shampoo, it will create a white, pearly product.
• Skin conditioner, emollient  -Glycol stearate has the ability to smooth and soften the skin tissue when applied topically. Its fatty, thick texture allows it to fill in the tiny spaces that exist between the protein fibers. This makes glycol stearate what is known as an emollient. Especially beneficial for dry skin, glycol stearate is found in a wide variety of moisturizers, body lotions, body butters, shampoos and conditioners.
• Emulsion stabilizer – Glycol Stearate has mild surfactant properties, having a molecule with one water-loving end (hydrophilic) and one oil-loving end (lipophilic).  This enables EGMS to help hold oil particles in the water solution and prevent product separation.  This helps to extend the shelf-life of a product.
• Thickener – Both EGMS and Glycol Distearate work to build viscosity in a solution, making it thicker. 

 SAFETY OF GLYCOL STEARATE - According to the Cosmetic Ingredient Review Committee (CIR), a group of independent experts that evaluate the safety of cosmetics, Glycol Stearate is safe in the quantities used in cosmetic and personal care products. There have been reports of contact dermatitis and allergic reactions to Glycol Stearate, although this does not appear to be common. All in all, EGMS and its chemical cousin, Glycol Distearate appear to be safe ingredients at the concentrations found in cosmetic and personal care products. 

 Animal data for acute oral toxicity, skin and eye irritation, and sensitization show that these ingredients have low acute toxicity. Repeated insult patch test with 50% Glycol Distearate on 125 subjects presented no evidence of skin irritation or hypersensitivity. Human studies using formulations containing Glycol Stearate at levels of 2-5% reported no skin irritation or sensitization.

 Environment Canada, the leading Canadian cosmetics review panel, has also confirmed the overall safety of the ingredient. Glycol stearate is not known to have any toxic properties or to have a potential for mutagenic effects.  It is also approved without concern in the European Union. 

 SUMMARY – Pearlizing agents are valuable tools for the cosmetic formulator, as they give a rich, luxurious appearance to an otherwise drab product. Glycol Stearate, aka Ethylene Glycol Monostearate or EGMS, is one of the most commonly used pearlizing agents, and it usually serves multiple purposes in a shampoo or cosmetic.

 A close chemical relative, Glycol Distearate, also acts as a pearlizing agent, thickener, and emulsifier.  The biggest difference between the two is that Glycol Stearate is an emollient and re-fatting agent for the skin, while Glycol Distearate is an occlusive, forming a film on the skin that prevents moisture loss. 

 The good news about pearlizing agents is that they are visibly identified by the opalescent appearance of the product and they are regarded as safe for cosmetics in the US, Canada and EU.  There is no scientific established reason to avoid these chemical compounds. The bad news is that even these harmless ingredients have occasionally been traced to allergic reactions by humans with sensitive skin.  For every shampoo ingredient known to mankind, there is some person, and possible animal, that will have a negative reaction.  Groomers should insist on knowing all of the ingredients for each product we use in our professional service.  

REFERENCES:

Cosmeticsinfo.org

CIR REVIEW: http://online.personalcarecouncil.org/ctfa-static/online/lists/cir-pdfs/pr237.PDF

SkinStore.com Glycol Stearate: http://www.skinstore.com/glycol-stearate.aspx

European Commission Health and Consumers/CosIng/Glycol Stearate. 

REMINDER:  Our book, Beyond Suds & Scent – Understanding Pet Shampoos and Conditioners is available from www.shop.bbird.biz  This book was written to give pet groomers and pet product professionals a foundation of understanding about the workings of our products.  Start your journey into the bottle NOW! 

 

Comments

[Ammarah]

thank you sooo much. this was so helpful for my assignment i am doing on cosmetics

[esye]

Thank you so much. Very helpfully.

[Temitope]

Thanks for the info. I hope to give it a try. I hope my shampoo and liquid wash look better.
I'll keep you posted. Thanks once again

[Ibkhan]

Hi all respected member and experienced staff, please help me sort out , I have made cold process liquid soap from coconut and olive oil, using KOH after dilution its transparent amber, I want it to turn milky/bright white I tried using Titanium dioxide, it worked but only for thicker/viscous formulation it didn't worked in thin runny formulation, it settle down after 5-6 hours and is not stable in liquid formulation please guide me through , to get non toxic bright