Will wood surfaces cause silicone cure inhibition?

Article courtesy of Smooth-On, Inc.

We often get questions from customers looking to make silicone rubber molds of models made from different types of wood.  Some have complained that the silicone rubber has been inhibited.  We decided to test the compatibility between both tin-cure and platinum-cure silicone against as many different types of wood as we could find.

We tested different types of wood (cross-cut to expose the raw wood) with no sealing or release agents applied to the exposed raw wood surface.

The results were as follows:

Tin Cure Silicones (Mold Max™ and OOMOO™) experienced inhibition with only one type of exposed raw wood;  Red Pine.

Platinum Cure Silicones (Mold Star™, Smooth-Sil™ and Sorta-Clear™) experienced inhibition with 4 types of exposed raw wood;   

  • Red Pine
  • Southern Yellow Pine
  • Eastern White Pine
  • Basswood

Can You Apply Silicone Rubber After Sealing a Wood Surface?  If you seal the wood surface with at least two layers of a high quality clear acrylic spray (Krylon Clear Acrylic), both tin-cure and platinum-cure silicone should cure without signs of inhibition.

List of Wood Sample Types Tested

Alaskan Cedar, Elm, Apple, Ash White, Aspen, Bald Cypress, Balsam Fir, Basswood, Beech, Black Ash, Black Locust, Butternut, Catalpa, Cherry, Chestnut, Coffee Tree, Douglas-Fir, Eastern Hemlock, Eastern Red Cedar, Eastern White Pine, East Larch, Hickory, Honey Locust, Hophornbeam, Madrone, Northern White Cedar, Pacific Yew, Paper Birch, Port Orford Cedar, Red Alder, Red Maple, Red Pine, Redwood, Southern Yellow Pine, Sassafras, Sugar Maple, Sycamore, Tupelo, Western Red Cedar, Walnut, White Oak, Willow, Yellow Birch, Yellow Poplar.



This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.