In the jet set age when one has to match looks with time constraints the best option to keep the long tresses glossy and bouncing is to go for a hair dryer. It is also known as a blow dryer and is a tool, which is electromechanical. It blows hot air over hair that is damp or wet to speed up the process of evaporation.
Towards the end of the 19th century hair dryers made its debut. In order to work it relied on generation of heat and mechanized flow of air. Alexander Godefroy invented the first model for his French salon. The convenient domestic hand held dryer popped up in 1920. Coils of wire run through the gadget which when heated produced hot air.
Hair dryers help but cannot by itself style the hair. For it brushes, combs and other aids are required. Since the 1920’s different hair dryer designs have been granted patents. But that is only concerned with the exterior facelift. The basic skeletal framework of the inside has remained the same, except for addition of some safety points.
Hair dryers have become indispensable. There is a general idea that sitting around with wet hair might lead to colds and sniffles. Whatever the reason the hair dryer has come to stay and the only way it is going to be dislodged is the way mankind is more prone to hair loss than never before. To suit the change new bald fashions have come into vogue and this might well spell the end of the road for the electromechanical hair dryer.
The principle underlying the mechanism of the hair dryer is the speeding up of the process of evaporation from the hair. The hot air emitted from the gadget envelops the head with an umbrella of warmth, which is hotter than the room temperature. Air that is warm can hold more moisture than what the air in the rest of the room can, at that point of time. The molecules in water droplets, no longer being attracted to each other, move onto the gas stage from the liquid one.
To produce the hot air only two things are required – a fan operated by a motor and a coil for the purpose of heating. Heating energy is turned into convective heat. When the tool is plugged in and switched on currents begins to run through it. Power is supplied to the coiled wire that becomes heated. In the next phase the current causes the small motor to start spinning which in turn whirls the fan. It generates an airflow. This flow is now directed down the hairdryer’s barrel over and into the heated elements. Heat rises and the air becomes hot by the process of forced convection. The warm and hot air now streams out from the nozzle of the barrel.
The small fan looks like a water wheel or hydraulic turbine. But instead of gathering in the potential energy from flowing water the trick inside a hair dryer is done by electrical energy to produce the hot flow of air. The tiny fan is fixed to the nose of the motor. When power is fed in both the fan and the motor start to spin. The movements of the blades of the fan are centrifugal and hence it draws air in by way of small circular inlets in the sides of the object. A screen that stops protects these holes from other items like strands of hair getting sucked in also. The heated air is then pushed through the barrel of the tool. Most of the latest models can be set at high or low airflow requirements. A controlling switch modulates the speed of the motor by altering the rate of current flow.
The material from which the wire is made is known as nichrome. This is an alloy of nickel and chromium. It is used for common household appliances like curling irons and toasters. Nichrome wires are good producers of heat. Compared to copper it is a poor conductor of electricity. The resistance allows it to heat to satisfactory required levels. On the other hand the use of iron is not practical because it rusts quickly at the temperature used for hair dryers, toasters and the like. The fan generates the airflow. It passes through the heated elements and out through the nozzle. Cool air is now taken in and the cycle continues. The temperature of the air coming out depends on the wattage being used. Some models use 1875 watts.
Some hair specialists are worried that this much of heat can cause damage not only to the hair but also to the scalp. Here arises the question of safety measures when mass production of hair dryers has become an industry and the device has invaded nearly each and every home. There must be a cut-off switch for safety because the scalp can get torched if the temperature shoots up to more than 140 degrees Fahrenheit. For this heat sensors can be used for tripping the errant current flow. A simple bimetallic strip can do the job. It consists of two metal sheets, which expand when heated but each at different rates. This causes the one which has grown larger, to bend and trigger off a switch-off. For more enhanced safety a thermal fuse can be fixed. It will prevent fires and aggressively break the circuit if the temperature rises abnormally. The outside the hair dryer has to be properly insulated otherwise it will become too hot to handle. Usually an insulated sheet lines the plastic exterior.
There is one hair dryer that is safe and free. It is the Sun. Hairstyling is as old as the hills. In the morning after a bath wet hair was coaxed into waves with the help of pencils. By the end of the day the Sun had done its part and bouncy waves made my lady prettier than ever before. But hair is fast joining the endangered list!