Knotty girls could face a brush with disaster. 

Hair maintenance is an all-too-important, albeit tricky form of self-care that, if mishandled, could leave folks with spilt ends, warns a new, hair-raising report. 

Rather than traumatizing one’s tresses with excessive heat — which causes hair to become brittle — followed by immediate brushing, researchers from the University of Dublin suggest treating freshly straightened strands to a 30-minute to two-hour recovery phase before styling. 

“Application of heat causes a dramatic reduction in performance…which is completely restored by a period of resting” study authors explained. “This well–known effect, presumably due to dehydration and rehydration, is clearly and quantifiably demonstrated.”

Investigators created a machine to recreate the damaging effect of brushing tangled hair. Raking a brushes bristles through the knots can force tangles to move downward along a strand, stressing the hair and causing split ends, per the experts. 

For the analysis, clinicians conducted “Moving Loop Fatigue” tests on a variety of 12 different hair types, including straight, curly and strong, as well as both treated and natural hair prone to breakage. Testing each category, the insiders repeatedly bent the hair, forcing it through a tight loop, to simulate the stress that brushing has on a tangled mane. 

Owing to heat’s propensity for temporarily weakening hair, the specialists found that when hair was exposed to roughly 300-degrees of heat, it became less durable. Prior to adding heat, a strand of straight hair was able to withstand 234 cycles of the moving loop fatigue test. Those same locks, however, could only survive 38 cycles after being hit with heat. 

The durability of curly hair also dropped from 185 cycles to 40, determined the team, which attributed the breakage on both types of hair to dehydration from the heat. A few extremely dehydrated samples reportedly broke on the first cycle. 

But, when hair is allowed to rest and rehydrate before brushing, the damaging effects of heat reversed and the strands recovered. 

David Taylor, a professor with the University, told DailyMail, “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.”

“We need to do more tests to find out how long it takes for the hair to come back to full strength,” he added, “but I suspect that even a few minutes will make a difference.”

Taylor and his cohorts  also found that “strong” hair resisted splitting the longest, while split–prone hair formed internal cracks early.

But the pro urged folks of all hair types to treat their tresses with tender loving care. 

“Some people have hair which is just naturally prone to splitting, so there’s not much they can do about that,” said Taylor, noting that long hair is more likely to split than short hair. “For the rest of us, be aware that any kind of treatment – coloring, straightening, etc – could be detrimental.”

“But the good news is that it’s not forever, so if a certain treatment causes problems, don’t do it again.”