Prep 220 Commercial Coating Remover (Gel) Removes urethanes, alkyds and most two-component epoxies from metal or concrete. Recommended for use on coated concrete floors. To remove existing floor coatings use Prep 220. It will remove the old coating and provide an additional 1-2 mils of profile. Prep 220 is slightly less viscous and more appropriate for horizontal surfaces. Prep 240 is more viscous and can build a thicker film when applied to vertical surfaces. All DuraPrep products NEED TIME to penetrate the coatings and lift them off. Most coatings lift off in 2 to 24 hours. If possible, spray the coating removers on the coating in the afternoon and leave it overnight. By the next morning the job will be done. Allow extra time for cooler temperatures.