While normally not required we always recommend using a primer. Our primer is actually a high performance epoxy that we call a primer only because it goes down first. It outperforms 95% of all other actual epoxy coatings. Using a primer will provide extra adhesion, strengthen older concrete and extend the coverage of the epoxy coating layer by up to 25% which can come in handy if your floor size is close to or slightly over the stated kit coverage. Use a primer in lieu of purchasing the Add On Half Kit, it makes for a better job. Also see are latest primer addition, our No Prep instant Primer. This remarkable primer applies to any surface without prep and allows you to coat over it with any ArmorGarage epoxy coating product instantly. Saves prep time, dry time and money by not having to grind or etch. Now you can prime and epoxy in one day by using this game changing product.