O goodness yes. Clean, clean and clean. Then etch with muriatic acid and BE EXTREMLY CAREFUL WITH THIS. DO NOT EVEN BREATH THIS STUFF IT WILL BURN YOUR LUNGS OUT!!! Wear acid proof gloves and eye googles. Work fast. This stuff is EXTREMELY DANGEROUS. I've done it several times so I know. Also if it's a old floor with grease and oil on it rent a steam cleaner and before you etch it steam clean it.