I have to respectfully disagree with this recommendation. There is no compatibality issue between epoxy and CURED polyester or vinylester resins. The Cte between the three is close enough to be inconsequential. The most important property for a repair resin is adhesion and epoxies have unquestionably superior adhesion to the other two types for at least two reasons: 1) uncured epoxy resin hass far lower surface tension (it is 'wetter', like comparing soapy water to pure water)and 2)epoxies are solvent-free resin systems. Vinyl and polyester resins both depend on the solvent styrene(vinylbenzene) to reduuce viscosity to a usable level. This is a 'reactive' solvent which means some of it becomes part of the cured resin. But not all of it does so. The part that does not evaporates shortly after the resin transitions to a solid. The loss of this free solvent ALWAYS results in significant shrinkage of the cured mass thus reducing adhesion further. Look at the shrinkage numbers for epoxies vs vinyl/polyesters and you will see something like 10X more shrinkage compared to epoxy.

Shrinkage is not necessarily a bad thing in production; it helps de-mold the part. The lighter viscosity, faster processing times and cheaper price for vinyl/polyester makes them the right choice in production,especially since the advent of resin infusion.

But repairing and manufacturing are definitely different games.

For repairs 'stick' with epoxy

Jimbo