I was curious if you might be able to recommend the best product for the following application. After removing the VA tile from our 50+ year-old basement floor, we are left with a black adhesive residue that seems nearly impossible to remove. Our objective is to somehow cover up and seal the mastic, leaving a surface that can be prepared for painting. Do you have a product that will cover up this mastic and provide a base to which paint can adhere? Prior to painting, we will also need to level some other areas of the floor with a self-leveling thin-set product. Your recommendations are greatly appreciated. The floor area is about 500 square feet. I do appreciate your help.