Have you ever experienced your wet hair turning into a brittle, rough, hard, and rigid mess, right after applying certain hair products? It feels as if most of the moisture has been drawn out of your hair. This is what the curly hair community refers to as “Flash Drying”.
What Causes Flash Drying?
Hair is porous and its water uptake can vary according to the surrounding conditions. As hair absorbs water, it swells, and the diameter increases. This can be quite prominent with high porosity hair under high humidity conditions when there is more water in the air.
Humectants, high molecular weight starch-based molecules, and certain film-forming polymers can influence the movement of water molecules into and out of the hair shaft. They are considered to be the main culprit that may induce a sudden shift of water causing the hair to become hard, brittle, and frizzy.
Which Ingredients Cause Flash Drying?
Humectants are chemical molecules that can absorb water. Humectants are excellent moisturizing agents and are added to a formulation to keep hair hydrated. However, if certain humectants 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 draw the water out of the hair, resulting in dehydrated hair!
In simple terms, a humectant will absorb water molecules from wherever it will find it easily and in excess. If there are more water molecules in the air, it will absorb water from the air and deliver it to the hair, for more hydration. However, if more water is available in the hair and the air is dry, the humectant can pull water out of the hair, causing it to become dry.
“Flash Drying” of wet hair is potentially due to the excessive available water and its uptake by humectants, causing water outflow.
Film-forming ingredients are used in many hair care formulations to produce a fine film on the hair’s surface to protect it from external changes such as humidity. Many hair styling products, gels, curling custard, and 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 can be an obstacle to any further penetration of active ingredients and water molecules.
Water is a universal solvent and the primary cleansing liquid. It can be soft or hard depending upon the concentration of calcium and magnesium ions in the water. Hair will absorb these metal ions from tap water. Over time, metal ion deposits may lead to significant build-up on the hair cuticles. This build-up can hinder the penetration of water and moisture from hair products and lead to Flash Drying.
Products containing high amounts of glycerin (5.0 – 10.0%) may cause severe flash drying. These are products where glycerin is listed as the second or third ingredient. Although glycerin is an effective humectant and moisturizer for hair care products, under wet hair conditions, it may cause severe Flash Drying. This in turn can cause frizz. Most curlies avoid glycerin-containing styling products in humid conditions. In fact, glycerin is the most mentioned ingredient responsible for both Flash Drying and frizz.
Aloe vera is a fantastic ingredient for its wide range of benefits. It purportedly contains more than 300-400 different chemicals that work together in harmony. Some of these include polysaccharides, glycosides, and protein. Aloe vera can also cause sudden water loss and flash drying.
Conditioning polymers are common in hair care products. Most of them are large, high molecular weight molecules that form 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, giving a sensory feel of Flash Drying.
If you experience Flash Drying right after using a particular product, you can:
- Spritz or mist your hair with water to rehydrate and dilute out the agent that caused the flash drying (often glycerin or sorbitol)
- Carefully apply a low-polymer or oil containing leave-in conditioner
- Try plant-derived film-forming humectants instead.
Anyone can experience Flash Drying due to products and their environment. It is difficult to pinpoint exactly when and what causes it, as we all have different hair textures. The best way to know is to test products containing these ingredients and if they cause an issue, avoid them altogether.