I bought a 100% pure one, Australian. I've been putting it on multiple times a day, whenever I remember. Always at least twice tho. I was prepared for the tea tree oil to sting a bit, because I read warnings online about not using it neat but it's been fine. I put it on with a cotton bud. Currently it has a scab, but it does look as if most of it has gone, of course, it could just reappear as it heals!
I expected it to hurt when I scratched at it (the encouragement to come off) but it was a weird sensation, almost as if it didn't have the same amount of nerves in it as usual skin.