I have somewhere around 20 tattoos, all black and grey, and I have this same problem a lot. I know it's not my artist and I know it's not my aftercare as I follow the same regimen everytime and sometimes it happens and sometimes it doesn't.
What I have noticed is that it only seems to happen with pure black pigment. If it's is diluted to get different greys it doesn't seem to happen.
My artist and I have just come to accept that my body rejects the pure black and I'll probably have to go in to get it touched up. Luckily he doesn't charge me for this.
During the healing process I'll notice some sections of black develop a thick scab that lasts much longer than the rest of the peeling stage. Once it finally comes off the skin underneath is almost new. All I can think of is that I have a strong immune system and my body is detecting that pigment as something foreign and is trying to protect me from it. The touch ups always seem to take though.
I attached pictures of an example. Pure black pigment for some script, all done at the same time, all taken care of the same way, but sections have been rejected.
It's just your body my dude, make peace with it 😉
