Just to update, I have scarring on my arms caused by a skin parasite infection. My skin has thickened quite a bit, so I wanted to peel it. I decided on glycolic acid after asking questions here and elsewhere and reading everything I could.
I was really scared about using the glycolic acid, so I put it off a long time. Finally, mixed up a little at 35% and did a patch test which turned out o.k., so I did the top of my left arm just to see what would happen. I was wary, so I only left it on about 3 minutes, so of course, nothing happened. Three days later, I did it again, left it on 8 minutes. There was no burning or discomfort at all. No redness. When I was putting on the sunscreen afterwards, it seemed like some dead skin was rolling off, though. That evening, I did the right top arm and left it on for 8 minutes and nothing happened except a slight tingling on the skin between my thumb and first finger (Yes, I did hands too). I didn't even get the skin rolling off. So it's been 3 days, and I don't see much change at all in skin texture. I'm thinking of kicking it up to 40% for the next round. I don't think I need to wait a week, since it obviously had no effect on my skin that needs to heal.
Once I've done a few peels and can see or feel it is working, I'll slow it down, but right now, it's like pouring water on my skin. If the two peels on my left arm hadn't burned my hair off, I would swear it WAS water.
I'm also going to try to do a facial peel at 35%. I've never done one before, so this should be interesting. I had done DIY Vit. C serum before and it took about 2 weeks for it to start tingling at all. My skin is just so thick from all the sun damage over the years.
I'm not in a hurry. I'm going to give it six months to see how much progress I've made, and if I'm not getting enough, I'll step up to TCA.