Hi All - I have porcelain tile on the back porch and every time it rains, the tile gets dangerously slick (my dog is slippin' and slidin' like crazy). I want to rough up the surface so there is more grip to the step and tried pouring muriatic acid to eat thru the surface but no luck. Does anyone have some insight for this dilemma - if so, I would be grateful as I don't want to crunch up what's there and make a change if I don't have to! Thanks! CBM