Is one of the first things you ask whilst buying hair dryers how many watts they use? Then you are not alone. But, did you know that for hairdressers, it doesn’t actually matter? Read on for more information on hair drying, watt, and watt’s really important.

Many believe that in order to dry hair quickly, hair dryers need a certain amount of watts. This is not the case. According to scientific studies, there is an optimal level for drying hair. Here is the explanation:

The drying speed is influenced by two things:

  • The air humidity
  • The speed of the air

These two factors have a threshold that there is no need to exceed. For example, the humidity of the air that goes out of the hair dryer is under 4% if the temperature is 80°C, even in a humid bathroom. To increase the temperature to more than 80°C has no effect on the amount of time the hair takes to dry.

Did you know: It is important that the hair is a little damp when you start blow drying? It is the only way you can make the hair keep its shape until it is washed next. Want to know more? Check out how the hair takes shape when you blow dry it!

Don’t let the hair faint

It’s not unlikely that you have over-dried one section only to feel that the hair has “fainted”. No matter how hard you try to revive it, the hair remains lifeless and without elasticity. This can be explained: When the hair is already dry, the temperature of the hair rises when it’s continually exposed to the hot air. The natural bounce gets “burnt” out if it’s blow dried over and over again.

Learn more about the hairs structure here!

What happens inside the hairdryer, and I’m sorry for having to get a bit technical here, is that the air in the salon gets warmer and pushed in the direction the nozzle is pointing. The air in the room has a given temperature, for example 22°C, and a given humidity (which is the amount grams of water per cubic metre of air). The absolute humidity isn’t very important in this context.

The important thing is, is the relative humidity, which is the air’s ability to absorb water molecules. The relative humidity is dependent on the temperature of the air. In other words, by warming up the air through the hair dryer, you also increase the air’s ability to absorb moisture. The lower the humidity in the air, the more “drying power” it has. Understand?

Yes, it’s like saying that the beer gets cold quicker in the freezer than in the fridge, because the freezer has more “freezing power”. And the other way around as well: You have likely seen the dew that appears on a cold glass of beer on a warm summer day? What happens is that the temperature of the air close to the glass decreases, and that way its ability to hold humidity. And bam! Your glass has condensation.

Hot, but not too hot

To get the water in the wet hair to go over to gas, a lot of energy is needed. What happens in the hair when water goes from a liquid to a gas is that the water collects evaporation energy from the hair (in addition to the drying air). Are you cold after you get out of the sea? It’s the same thing. The temperature in the hair is kept lower than the temperature of the drying air.  And as long as the hair is wet, the temperature in the hair will be at what we call the wet sphere temperature. But when the free water has evaporated, the temperature in the hair will also increase in temperature until it reaches the same temperature as the drying air.

The hair doesn’t benefit from being heated up to high temperatures like this. The heating element inside of the hair dryer is very warm, and dust and pollution in the air can split and create charged ions. These will also affect and influence proteins, oil, and other desirable components in the hair. This creates discolouration and smell.

Water and hair are also charged with positive ions, and that’s why most good hair dryers have ionizers that add negative ions. It loosens “charged” water from the hair easier and cuts down the drying time.

Do you want to know more about drying techniques? Check out this blogpost!

Fast, but not too fast

The same goes for the speed of the airflow. What’s important is removing water molecules that lie closest to the airspace around the strands of hair. You can do this by creating turbulence in the air around each strand. Sufficient airflow from the hair dryer makes the hair blow, and that creates enough turbulence to remove the water. To increase it more than this doesn’t help. Not even the strengths of a hurricane would matter for the drying speed.

Remember: The airflow and the heat does not increase the time it takes to dry hair. It’s about getting the right combination of the two that gives the optimal effect for drying. The perfect combination of airflow and heat leaves the hair naturally bouncy and will leave it looking shiny for days.

On the lookout for a hair dryer that dries the hair optimally, completely without the hair overheating?  Learn more about Dual Air