I attempted to bond urethane rubber to stainless steel for an industrial application and it did not stick. What can I do?

Urethane rubber will not stick to some metals (for example; brass or stainless steel) under any circumstances.

Urethane rubbers that exude an oil (such as PMC-121® WET or PMC®-780 WET) will not bond permanently to any metal.

To get urethane rubber to bond to steel or other common metals, we recommend using a rubber that does not exude oil such as Vytaflex®, Reoflex® or Brush-On® urethanes.

You can increase your chance of a secure bond between urethane rubber and metal by:

  1. Etching or sanding the metal surface.
  2. Clean surface with solvent (acetone) and let dry.
  3. Mix and apply rubber.

Options: After step 2 above, spray a high quality SHELLAC onto the metal surface as a primer. Shellac is a good bonding primer for urethane rubber. Ure-Bond® II adhesive is a better primer for bonding urethane rubber to metal and is available from Smooth-On distributors.

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.