What glue do you use to glue silicone rubber to steel?

Answer 1

Silicone rubber is the most difficult polymer to join to anything using adhesives. It can be done cheaply, if care is taken. Here's one way.

You will need:

100 grit emery cloth or silicon carbide abrasive paper.

CRC Brake Parts Cleaner. Green can (Non-Chlorinated). This contains heptane, an activator/bonding agent for RTV silicone.

GE Silicone I Waterproof Silicone caulk. NotSilicone II! Comes in caulking gun tube - around $4.

Cheese grater - the cheap box kind with the sharp super-fine holes for scratching.

First try to roughen the steel using 100 grit silicon carbide paper or emery cloth. Then thoroughly degrease and clean using CRC brake parts cleaner.

Roughen the surface of the silicone rubber with the cheese grater, and spray with brake parts cleaner.

Spread a bead of the silicone caulk in an appropriate amount on the steel. Before positioning the silicone rubber into the caulk, lightly spray it with the brake parts cleaner. Then position the rubber and press it onto the caulk. No need to clamp. Allow a couple hours for handling, 24 hours for full use.

Good luck and YMMV.