Addition cure silicone rubbers are susceptible to cure inhibition by a number of products and materials. Take special care to ensure that the uncured silicone does not come into contact with any of the following materials or substances otherwise byou may well find that the silicone does not cure at all in the contaminated areas.

Products with a high moisture content or a high sulphur content are potentially themost damaging.

• Inhibiting Substances

• Wood

• mastic epoxy resin

• Natural rubber

• Silicone sealants

• Neoprene adhesive

• Vinyl adhesive

• Transparent wood glue

• Flexible compact PUR

• Plasticised PVC film*

• Foam latex and latex gloves*

• Cyanoacrylate adhesive* (super glue)

• Polyester resin

• Adhesive tape

• Coachwork polyester mastic

• Shellac

• Transparent PVC tubing*

• Condensation cure RTV

• CAF (all types)

*  PARTICULARLY ACTIVE

If you used Polyester resin for your GRP plug then that may well be the cause.