'I have just recently restarted a water-only regimen but I'm concerned about using a boar bristle brush, which is a requirement for water-only. Afraid that my hair would be damaged by bristle brushes I skipped them the first go around with water-only and thus couldn't keep up the regimen very long. I have read on the Kent Brush website that "Natural boar bristle will never damage human hair as they are both made of the same protein." Have you seen research that supports this?'
I did not really have to do any research to answer this question but I did anyway because I an insatiable appetite for it!
Any tool, from your fingers, a wide tooth comb, a fine tooth comb, a denman brush or boar bristle brush can damage your hair if used incorrectly.
It is completely inaccurate and misleading of Kent Brushes to say that as a brush is made of keratin, it will never damage hair. Boar bristle brushes are known for being stiff and uneven in length. Some people can use them all over the head but others just keep them for final smoothing of edges only as they find them too rough for all over use. Many naturals opt out all together.
I would say, try the boar bristle brush on a small section of hair and make a decision for yourself whether your hair can take it or not based on if your hair breaks or splits afterwards. Also there are some who do the water only technique without brushing, just have a look on youtube.
The Funny Answer
Erm, no there were no scientific papers on specific brush types and hair damage. I did, however, find a paper way back in 1958 that essentially said the kind of brushes that are common place now - nylon brushes - are evil. Ok, ok, it was not literally that but I do like the style of writing back then, it is very different to the technical writing that I am used to. It is also a testament to the fact that science DOES change! Here is a snapshot (British Journal of Dermatology, pp296-299, 1958).
Have you used a boar bristle brush? Would you recommend it?