The color of my urethane rubber is different compared to the last batch. Is there something wrong with the material? Will it perform the same as the last batch I received?

Article courtesy of Smooth-On, Inc.

As with many urethane rubber and resin formulations, color variation from batch to batch is common and is a function of color variability of raw materials that manufacturers like Smooth-On receives from suppliers.

Color of these types of products can change from batch to batch made in our factory and can vary from light to dark.

Whether light or dark, color has no effect on functionality or performance of the cured material.  Physical and performance properties will be the same from batch to batch and you can use the material with confidence.

Urethane rubbers and plastics are not UV resistant and cured material will darken in proportion to exposure (intensity and duration) to ultra violet light.  

The exception is when a particular urethane rubber or plastic is made with UV inhibitors to delay the effects of UV light.

Related FAQ: What are my options to delay the effects of Ultra Violet light on a urethane rubber or plastic product?



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.