The Science Behind Split Ends and How to Prevent Them
If you’re constantly battling with split ends, scientists might have the answer. Recent research has shed light on how heat styling can damage hair and what you can do to minimize the damage.
Experts have discovered that after using straighteners, it’s important to let your hair ‘recover’ before brushing it. Heat makes hair temporarily weaker and more brittle, which increases the likelihood of breakage under pressure. However, this effect is reversible, and all it takes is a little patience.
In their study, researchers found that hair fully recovered when allowed to ‘rest’ for two hours after being straightened. For those with limited time, waiting just half an hour can still be beneficial.
“The application of heat causes a dramatic reduction in performance…which is completely restored by a period of resting,” they wrote in the Journal of the Mechanical Behavior of Biomedical Materials. “This well-known effect, presumably due to dehydration and rehydration, is clearly and quantifiably demonstrated.”
Understanding the Impact of Heat on Hair
To better understand the effects of heat on hair, a team from the University of Dublin developed a machine that simulates what happens when you brush tangled hair. Professor David Taylor explained that individual hair strands are very thin and flexible, allowing them to literally tie themselves in knots – creating a tangle. When you brush your hair, you force the tangle to move along the hair, down to the end, which puts huge stresses on the hairs, potentially causing them to break or split.
The team tested various hair types, including straight, curly, strong, treated hair prone to breakage, and natural hair prone to breakage. Instead of pulling hair straight until it snaps, they used a ‘moving loop fatigue test’ to bend hair repeatedly and force it through a tight loop, simulating the stress of tangled hair being brushed.
Key Findings from the Study
Analysis revealed that heat significantly weakens hair. When hair was heated with straighteners at 150°C, the number of cycles it could withstand before breaking dropped dramatically. For example, straight hair that usually lasted 234 cycles only lasted 38 cycles after heating. Similarly, curly hair’s durability dropped from 185 cycles to 40.
“This is because heated hair becomes much more brittle and fails under brushing-like stress very quickly,” the experts explained. Some samples even broke on the first brush cycle after heating.
However, when heated wet hair was allowed to rest for two hours, its performance recovered almost completely. The team also discovered that this effect is reversible if the hair is given time to rehydrate.
“There’s enough water in the air to rehydrate dry hair, though it varies a lot depending on the humidity of the air around you,” Professor Taylor said. “We need to do more tests to find out how long it takes for the hair to come back to full strength, but I suspect that even a few minutes will make a difference.”
Tips for Preventing Split Ends
The team found that ‘strong’ hair resisted splitting the longest, while split-prone hair formed internal cracks early. Both curly and wet hair were affected by heat, but both also recovered almost completely within the two-hour timeframe.
When asked about advice for preventing split ends, Professor Taylor said: “Some people have hair which is just naturally prone to splitting, so there’s not much they can do about that. For the rest of us, be aware that any kind of treatment – colouring, straightening, etc – could be detrimental. But the good news is that it’s not for ever, so if a certain treatment causes problems, don’t do it again.”
He added that long hair is more likely to split than short hair, as the ends of our hair are naturally more brittle. Keeping these regularly trimmed could help prevent cracks from running up the length of the hair, causing breakage.
Additional Insights from Previous Research
Scientists have previously revealed the key to freeing tangles is by starting with brushing at the end and moving upwards. Harvard researchers created a model that simulated two entwined filaments to represent a tangle of hair, and analysed different ways of ‘brushing’ it so the hairs became free.
Their results, published in the journal Soft Matter, revealed that short brush strokes that start at the ‘free’ end of the hair and move towards the ‘clamped’ end are most effective.
