what do u do when applying a relaxer/perm??

i did my hair 2day and i used one of those brislte brush things that looks like a rat tail comb,but u use it when u apply a relaxer. the problem i have is that my hair starts 2 burn from the chemicals and i think its cuz using the brush to apply the relaxer takes 2 long. so how do u ladies apply it??

I used to do the finger application, but with a lot of practice I use the brush now.  I would do half brush half finger method until I felt fast enought to do the whole head. I don't what the benefits are of using a brush vs the fingers but I always seen the beautician use it.