Typically, porous floors are a good thing, up to a point, when applying any concrete coating. It enables the coating to achieve a good mechanical bond to the substrate. One thing to consider, however, is that it will reduce the coverage rate and DFT (dry film thickness) of the initial coat, so you may need additional product to account for the absorption on the first coat. It is very rare situations that a penetrating sealer should be used, and in cases where the floor is extremely porous, a densifier is usually a better option, but will require grinding of the surface after the 5-7 day reaction time needed to work. In most all cases, you do not want to use a sealer or densifier, and applying additional coats Rust Bullet concrete coatings to achieve the appropriate DFT will give the best results.