We have found that the most efficient way to prep a concrete floor for coating is by mechanical grinding. Our installers use a diamond encrusted floor grinder with a powerful dust collection system that removes a thin surface layer of the concrete. When complete your stained or painted concrete will be white, porous and ready to accept the epoxy coating. A typical 2 or 3 car garage can take up to 2-4 hours to grind. Some companies will acid wash your floor if it is free of oil and paint, however the acid washing process presents its own set of problems. The acid being used must be diluted correctly or it can damage the concrete. Additionally, the process can create dangerous fumes to, not to mention that it requires proper disposal of the acid water, which can easily damage your landscaping, to include your pavers, plants, grass, etc. The acid wash also leaves behind a wet concrete dust film that must be completely removed from the pores or it could prevent the epoxy from correctly bonding to the concrete floor. This can result in defects to the coating of your floor as the epoxy cures and eventually cause delamination. Additionally the floor would need to completely dry which could take several additional days delaying the start of the applying the epoxy and extending the time to return your garage to service.