Wednesday, October 10, 2018

BEAUTY SCIENCE: Dry Shampoo


Are you a dry shampoo addict or just use it in a pinch? It is one of the most handy items in your beauty arsenal. It can be great on a hectic day or for added lift & texture on 2nd or even 3rd day hair. There has been a dry shampoo explosion in the past few years. Like most fads, this one’s a repeat—Victorians sprinkled powdered arrowroot on their locks. Today’s formulations are a little more complicated, but they do basically the same thing: soak up grease.

However, not all dry shampoos are created equal.  Some of the cheaper ones may contain harmful ingredients like talc!  Below are the most common ingredients in dry shampoo.  The really good quality salon products can be a life/time saver.  Be a knowledgeable consumer...read the label!

Talc is used in dry shampoo formulas because of its excellent absorbent abilities. Talc is a material made of magnesium, silicon, and oxygen, but may also have asbestos fibers. It’s the asbestos fibers that are the scary part, which can pose health risks such as respiratory toxicity as well as cancer.

Your better choice to absorb those excess oils - cornstarch!  Your scalp secretes a mixture of lipids called sebum, which makes tresses oily after a few days sans shower. White, powdery cornstarch binds to sebum’s fatty-acid chains through weak electric interactions called van der Waals forces. 

Kaolin is another ingredient used in dry shampoo.  Mined for centuries from Kao-ling, a hill in southeast China, this soft clay absorbs grease and cloaks the shine of unwashed locks. Its hydrous aluminum silicates coat hair strands, reducing their reflectivity and creating a matte look. 

Laminaria saccharina Extract. Obstetricians sometimes insert a laminaria stick (made from a type of brown algae) in the cervix to induce labor—it absorbs moisture and expands, aiding dilation.

Brown algae also makes for a decent sebum sponge. Suppliers farm the algae, chop it up, and treat it in a solution of water, glycerin, and other stuff they wouldn’t disclose to extract this ingredient.  Maybe not a best choice ingredients.

Magnesium Stearate.  This anti-caking agent coats the surface of starch molecules to keep them from clumping—one of starch’s favorite leisure activities. Magnesium stearate is also the culprit behind bathtub rings; magnesium and calcium in water swap ions with sodium stearate in soap to form the waxy solid that you have to scrub from your tub.  Hmmmmm?

When you spray on your dry shampoo, do you notice the force with which it comes out.  That is due to LPG's (Liquid Petroleum Gas), a combination of  Butane, Propane & Isobutane.  It's what is used as the propellant to force chemicals out of the can and nebulize them into a fine mist. Aerosol cosmetics like hair spray used chlorofluorocarbons until the late ’70s—after scientists realized CFCs wreak havoc on Earth’s ozone layer, the US government banned them. Liquefied petroleum gas (often a combo of butane, propane, and isobutane) became the go-to alternative. With a boiling point below 0 degrees Celsius under normal conditions, LPG is kept around 50 psi in the bottle to preserve its liquid state. The ingredient is safe, just don’t use dry shampoo near an open flame—LPG is highly flammable, so you could end up with your hair on fire.

Phenoxyethanol fights the bacteria in the product.  While this chemical can be found naturally in green tea (go, nature!) we’re talking about the synthetically manufactured version that’s known as a “natural identical.” We’re on team “if it ain’t broke, don’t fix it,” so we’re not sure why anyone would opt for a lab ingredient versus the original goodness. Phenoxyethanol’s purpose is to help fight bacteria. The EU and Japan have approved the use for up to 1%, but we can’t help but think of the cumulative effects of this controversial dry shampoo ingredient. The jury is still out on Phenoxyethanol long term effects, but studies have shown it can lead to developmental and reproductive issues as well as being linked to cancer. You may want to stick with the green tea version.

The purpose of dry shampoo is to draw moisture and oil away from the scalp, and this is where alcohol comes in.  The liquid alcohol suspends solids without dissolving them and carries the oil-absorbing particles out of the bottle when dispensed. It evaporates quickly after it hits hair roots and absorbs body heat—the endothermic process creates a cooling effect that soothes an itchy, dirty scalp. Alcohol can be extremely drying to our delicate strands and head, absorbing natural oils that are needed for a healthy scalp. Excessive use of dry shampoos that contain alcohol can lead to long-term hair and scalp damage. When dry shampoo is used too often, it can cause dandruff, dryness and blocked pores.

Finally, there is the Siloxane, Silicones & Octamethylcyclotetrasiloxanes.  Silicones and siloxanes are used in a variety of conventional beauty products and are commonly included for their ability to not break down during application and to help product formulas dry faster. There has been a slight shift away from this questionable ingredient after scientific studies, and Canada and California have been taking a closer look, but overall, silicones are still very common in personal care products.


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