Prep 240 Industrial Coating Remover (Gel) Lifts the most difficult graffiti and high performance coatings such as highly cross-linked urethane's and epoxy topcoats and primers, the toughest industrial coatings and fuel resistant primers. Recommended for use in petrochemical plants and power generation facilities, including nuclear plants. 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.