Vinamold Slabs of rubber requires heating to 170ºC and is then poured over the plug, setting as it cools. A double skin pan or similar principle is needed to avoid overheating when melting. Air bubbles will appear on the rubber surface if moisture is in the plug, prior sealing with polyurethane varnish is recommended. 3 Grades available, Natural (softest), White (medium), Yellow (durable) can be mixed to vary flexibility. Moulds no longer required can be cut up, melted and re-used again.