Hi Rubickscube
here is an extract from my tattoo ebook that may answer your question
Can tattoos be used to cover scar tissue?
This is a common question which has been asked many times. This is usually linked to surface scarring either though accident or self inflicted. (Please note that cutting is a serious condition and professional help should be sought immediately. I would suggest this website as a first step http://www.wikihow.com/Stop-Cutting-Yourself).
Tattooing can cover most light to medium surface scars, the success is dependant on the condition of the skin, the size of the scar, and the depth of the scar.
The deeper and bigger the scar is the harder it is to place tattoo pigment as the epidermal area is already damaged.
Tattooing should never be done on fresh scar tissue. The area has to have totally healed before any attempt is done to tattoo it.
Hope that helps
Take Care
Matthew
Only an experienced tattoo artist should ever attempt to cover scar tissue.
Unfortunately deep scarring, burns, and skin graphs do not always tattoo as easily. This is because of the usually pronounced damage within the dermis.