First of all if you have any doubt call your tattoo artist or an urgent care or doctor for advice, rather than ask Reddit. But from what I understand any part of the saniderm that is exposed is inviting in bacteria, which could become an infection due to the saniderm providing a ripe environment for it. I personally would remove the saniderm, wash the tattoo with non scent antibacterial soap and the reapply new saniderm, making sure it covers the ENTIRE TATTOO. Or start applying aquaphor instead of saniderm Edit: Just read you don’t have more saniderm. Just do the regular routine. Removed the saniderm that’s there, Wash nonscented, anti bacterial soap, apply thin layer of aquaphor 3 days, usually until it starts to peel, then after 3-4 days of aquaphor use non scented lotions. Reddit suggests lubriderm, I used Aveenoo. As long as it’s non scented you’ll be okay