Gelcoat can only be applied over TotalBoat TotalProtect epoxy barrier coat once it has completely cured for at least 48 hours under normal application conditions, becoming a completely inert coating, and it has been sanded with 80-grit sandpaper.
Gelcoat will cure if it is applied to an inert substrate, such as completely cured TotalProtect, but it relies completely on creating a strong mechanical bond. Sanding the TotalProtect with 80-grit sandpaper, then thoroughly removing any of the the sanding residue and surface contaminants with acetone will give the gelcoat a properly prepared surface to bond to.