The Grand Ayatollah Vahid Khorasani answered a question about performing Wudhu with having tattoos.
Question: What is the ruling on performing Wudhu with having tattoos?
The Grand Ayatollah Vahid Khorasani: If tattoo prevents water reaching the skin, is not allowed and causes Wudhu and Qosl to be invalidated. And if a person has done such a thing, must remove it even if it is difficult. And in any case it is an adornment (for women) and must be covered from non-Mahrams.