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Flash Drying

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Verna Meachum

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Flash hair drying is a technical term that you’ve probably heard at least once within the curly hair community. But what exactly is it? It is defined as “an instant flush out of the water from hair” as a result of a product application or treatment. If you’ve ever experienced this, it feels like most of the moisture has been drawn out of your hair. It could be a shocking experience where wet hair, all of a sudden turns into brittle, rough, hard, and rigid hair, which then becomes difficult to manage and style.

Is it Good or Bad?

No, it is not good at all. No one wants frizzy, brittle, rough, hard hair, on top of spiky hairs spread randomly all over your head. Even under wet hair conditions, your hair seems lifeless.

So, what is this? What is the cause? We need answers…

Causes of Flash Drying

Here’s a little science to help break things down. Hair is porous, bio-composite material that may absorb water, and its water uptake varies according to the surrounding humidity conditions. As hair absorbs water, it swells, and its diameter increases due to high water level inside. This is even more prominent under high humidity conditions when there is more water outside. Water uptake by hair is a “Two Way Traffic” where hair absorbs or may desorb (lose) water depending upon the surrounding conditions. Damaged hair fibers are more susceptible to this and are known to suffer these water equilibrium changes more severely.

Certain chemical agents and ingredients can influence (or disturb) this two-way traffic of water molecules across the hair shaft (in and out). Humectants, e.g., glycerin, is one familiar example of such ingredient abundantly used in hair care products. Other moisturizing ingredients also have this ability to retain moisture content while their water uptake capacity varies depending upon their molecular structure and chemistry. Aloe vera and polymeric ingredients are also known for the same reasons. How could these ingredients cause flash drying? There could be various possible mechanisms involved.

Humectant Mechanism: Water Outflow

Humectants are chemical molecules that can absorb water. Some examples are glycerin, propylene glycol, urea, sorbitol, and other polyhydric alcohols. Starch-based molecules, e.g., glucose and lactose, can also absorb moisture. Humectants are excellent moisturizing agents and are added to a formulation to keep hair hydrated. However, if they are used in large amounts or under low humidity conditions (dry weather), they may act in a slightly different way. They can absorb water molecules from the hair cortex and flush them out, resulting in less water content for hair. In simple terms, glycerin will absorb water molecules from wherever it will find it easily and in excess. If there are more water molecules in the air, glycerin will absorb from the air and will deliver to hair, thus causing the hair to be more hydrated. However, if more water is available in the hair (and the air is dry low humidity), it will flush water out of the hair, and cause the hair to become dry — this follows the thermodynamic equilibrium.

“Flash drying” of wet hair is potentially due to the excessive available water and its uptake by humectants. There is plenty of water, and applying humectant will shift the water equilibrium towards surrounding, causing water outflow.

Surface Coating Mechanism

Film-forming ingredients are used in hair care formulations to produce a fine film on the hair’s surface to protect hair from external changes such as humidity. Hairstyling products, gels, curling custard, or creams contain these polymeric film formers. Besides their beneficial role in adding style and volume to hair, their film can sometimes make hair stiff and hard — this may happen suddenly, even if your hair is wet. Thus, the tough coating is an obstacle for any further penetration of active ingredients and water molecules.

Hard Water: Deposits of Calcium & Magnesium

Water is a universal solvent and is the primary cleansing liquid. It can be soft or hard, depending upon the concentration level of calcium and magnesium ions. Hair uptakes these metal ions from tap water. Repeated deposits of metal ions may lead to crystalline build-up on the outer cuticular surface of the hair fiber. Recent studies have demonstrated that metal build-up alters the physicochemical and cosmetic features of hairs (combing force, sensory feel, and shine).2-3 This significant build-up of metal may hinder the penetration of active ingredients leading to unwanted and undesired results. Flash drying is one of those results.

Ingredients to Avoid Flash Drying

With the above discussion, we can draw a list of chemicals and ingredients that we should possibly avoid preventing any flash drying.

Glycerin. Our old friend glycerin has been around for so many years. The products containing high amounts of glycerin (5.0 – 10.0%) may cause severe flash drying. Though it is a cost-effective humectant/moisturizer for skin and hair care products, it works in two-way traffic, and under wet hair conditions, may cause flash drying. Glycerin is the most mentioned ingredient responsible for flash drying.

Aloe Vera. Aloe vera is a fantastic ingredient for its wide ranges of benefits. It contains more than 300-400 different chemicals that work together to provide dermo-cosmetics performance. The main components are various polysaccharides (Starch), glycosides, such as mannan (Mannose sugar) and its acylate derivative acemannan.4 It also contains a protein molecule made up of essential amino acids. The hair care products having aloe vera ingredients are also susceptible to cause flash drying. The possible reason is the synergistic effect of starch molecules and proteins. These molecules are capable of withholding and attracting large amounts of water from the hair, inducing a sudden water loss.

Film-forming Polymers. Conditioning polymers are a common element of hair care products. Most of them are large, high molecular weight molecules forming a thin coating on the hair shaft. PVP and its derivatives are primary examples of such polymers offering good moisture resistance and styling under extreme humidity conditions. However, excessive use and repeated applications may cause build-up and make hair stiff hardened. The water repellent layer changes the surface properties of hair, and the subsequent application of cleansing and conditioning products respond differently. Hair –water balance is changed, and hair looks dried, giving a sensory feel of “Flash Drying.”

Troubleshoot for Flash Drying

How can we avoid it?

• Regularly use of deep cleansing shampoo, having moderately acidic pH to remove/minimize product build-up.

• Avoid sulfate shampoos. They increase hair protein loss and make hair damaged and fragile, which subsequently alter hair-moisture equilibrium and induce flash drying.

• If your hair is sensitive to proteins, it’s best to avoid products having large protein molecules.

• Use soft water for everyday cleansing; the metal build-up is detrimental for your hair health. Acidic pH shampoo will help the removal of calcium and magnesium ions.

• Don’t use heavy high molecular weight oils/butter and waxes such as beeswax, petrolatum, carnauba wax.

In case you have flash drying right after using a particular product, and you need a quick solution:

• Immediately wash your hair using a deep cleansing shampoo to remove product residue.

• Apply a regular conditioner to detangle your hair and rinse it off.

• Apply a low polymeric leave-in conditioner. Pay attention to ingredient listing; the product should not have polymeric styling ingredients.


Flash drying is a surprise shocking experience, and anyone of us can experience this. It is difficult and challenging to pinpoint exactly when and what caused the issue, as every one of us has different textures. Humectants, high molecular weight starch-based molecules, and film-forming polymers are considered as the main ingredient that may induce sudden flush out of water. Hair becomes hard, brittle, and frizzy. The remedy is to avoid these ingredients and try to remove the product quickly using a mild sulfate-free cleansing shampoo.


1.  Zviak, C., The Science of Hair Care. Taylor & Francis: 2005.

2. Godfrey, S.; Staite, W.; Bowtell, P.; Marsh, J., Metals in female scalp hair globally and its impact on perceived hair health. Inter. J. of Cosmet. Sci 2013, 35 (3), 264-271.

3.  Evans, A. O.; Marsh, J. M.; Wickett, R. R., The structural implications of water hardness metal uptake by human hair. Inter. J. of Cosmet. Sci 2011, 477-482.

4.  Burlando, B.; Verotta, L.; Cornara, L.; Bottini-Massa, E., Herbal Principles in Cosmetics: Properties and Mechanisms of Action. CRC Press: 2010.

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