Source: The Conversation (Au and NZ) – By Magdalena Wajrak, Senior Lecturer in Chemistry, Edith Cowan University
If you’ve been in the market for a new hair dryer, you’ve likely seen advertising for ionic ones. Some claim to produce negative ions in the millions – with or without the help of added minerals like tourmaline.
The broader claim is usually that these ions break water molecules into micro-droplets, resulting in faster drying and reducing frizz to give you super smooth, shiny-looking hair.
Are ionic hairdryers actually capable of doing what they claim? To understand this, we need to briefly delve into some fundamentals.
Wait, what is an ion?
All matter is composed of invisible building blocks called atoms. But they’re not the smallest things we know of. Atoms contain subatomic particles – protons, neutrons and electrons.
Every atom has a nucleus, a very dense centre made up of protons and neutrons. The number of protons determines what chemical element the atom is. Hydrogen has one proton, carbon has six, oxygen has eight, and so on. Molecules are groups of two or more atoms that form a chemical element; an oxygen molecule consists of two oxygen atoms, for example.How does all this relate to ions? This is where electric charge comes in. All subatomic particles have an electric charge. Protons have a positive charge (+), electrons have a negative charge (-) and neutrons are, as the name suggests, neutral.
The nucleus has a positive charge overall, thanks to all the protons. Negatively charged electrons surround the nucleus because opposite charges attract. This is called electrostatic force, and it is this force that actually keeps the electrons from flying off away from the nucleus.
But electrostatic force is pretty weak. When materials touch or are rubbed together, we get the triboelectric effect – electrons can transfer from one surface to the other. This produces ions: positively or negatively charged atoms or molecules. For example, a negative oxygen ion is oxygen that’s gained an extra electron.
What do ions have to do with hair, then?
For the most part, hair is composed of large complex molecules called keratin proteins. In turn, keratin molecules are composed of various chemical groups, such as carboxyl groups, amino groups and disulfide groups. These can gain or lose electrons.
So, when hair is dried with hot air or is subjected to friction, keratin fibres lose electrons via the triboelectric effect – they become positively charged.
Remember electrostatic force? When hair strands are positively charged they push away from each other, and you get frizz and fly-aways.
This is why hairdryer manufacturers have come up with the idea to neutralise the positive charge with negative ions from the hairdryer. In theory, this should return the charges in your hair to neutral and therefore reduce frizz.
How do hair dryers generate negative ions?
This part is just physics. Although different manufacturers may use slightly different methods, most ionic hairdryers use high voltage applied to a fine wire inside the hairdryer.
This creates a very strong electric field near the outlet where the hot air is blowing. It sends electrons into the surrounding air, producing negatively charged ions – mostly oxygen and nitrogen. The airflow then carries these ions out with the hot air.
To increase the number of negative ions produced during this process, some ionic hairdryers incorporate a mineral called tourmaline which emits negative ions naturally.
Although theory does support the claim that negative ions might neutralise the electrostatic charge of positively charged hair, in practice the amount of ionisation generated by the ionic hairdryers is very small because they’re limited by the voltage applied (typically 1,600V).
Sure, you could generate a huge amount of negative ions with enough electricity, but that’s beyond the scope of an everyday beauty appliance.
The effect would likely be subtle
Overall, this means the effects from an ionic hair dryer would likely be subtle.
Other factors will play a more significant role in smoothness – such as your hair type, hair quality (whether it has been chemically damaged by bleaching or dyes) and what products have been used on the hair prior to drying.
There is also no scientific proof that ionic hairdryers dry hair faster by breaking up water droplets more efficiently, although some studies have demonstrated that ions enhance the evaporation rate of water.
Ultimately, before investing in a very expensive hair dryer, you may want to look at improving the health of your hair in general. Negative ions – while plausible in theory – can only take you so far.
– ref. How do ionic hair dryers work? Can they do what they promise? – https://theconversation.com/how-do-ionic-hair-dryers-work-can-they-do-what-they-promise-278785
