u/Fun4TheNight218

I'm trying to redo the floor in my laundry room. I'm currently pulling up tiles that are really old, I mean old enough that if I mention the material I'm pretty sure they're made with my post gets flagged. But that's just a point to help date them and maybe help indicate what this adhesive might be, because they were applied to the concrete underneath with a black, sticky substance, could be tar, could just be something very much like it. The tiles are coming up with the help of a heat gun and elbow grease, but a lot of tar is staying behind. I don't think there will be any way to get it all up.

So with that addition to the bare concrete, is there anything else I should do to prep the floor before I try to put the self-leveler down?