Can a polyester patching material be used to repair stone on an exterior?

Polyester resins breakdown in the presence of ultra violet(UV) light. For this reason polyesters should never be used outdoors. For outside repairs it is advisable to use an epoxy resin. Epoxy resins are generally more resistant to UV light. Check with the manufacturer of these resins for recommendations for exterior use.

TIP There are several propriety patching materials being introduced that seem to hold up to UV well. Frequently check with the stone trade journals and attend the stone shows for information on these new products.