Liquid silicone rubber (LSR) naturally ranges from clear to opaque white. Adding 1-3% pigment to LSR achieves desired colors while maintaining its physical properties.
Key Pigmentation Facts:
- Standard mix ratio: 98% LSR, 2% colorant by weight
- Color remains stable across material hardnesses
- Part thickness affects color appearance – thinner parts appear lighter
- Medical grade colorants meet USP Class VI requirements
- Standard colors don’t affect part cost; custom matching available
Colors serve several purposes: distinguishing similar parts, indicating revision levels, providing visual verification, and matching device aesthetics.
Note that clear LSR may yellow over time.
Manufacturing Process:
A concentrated color paste is added as a third stream while LSR flows into the press, creating a uniformly tinted material before molding and curing begins.
Figure 1: 98% Liquid Silicone Rubber + 2% Color Paste = 100% tinted LSR
Color Measurement:
Apple Rubber uses the CAPSURE® color meter to match colors to the Pantone system. This device contains over 10,000 Pantone colors with corresponding sRGB, Adobe RGB, HTML, Lab, and XYZ values. Testing is performed on 6″ x 6″ x 0.080″ specimens using Silopren™ LSR 2070 (70 shore A durometer) with 2% color paste.
The Pantone results for our available paste colors can be found below in the following tables.
With over 70 color options available and the ability to create custom matches, Apple Rubber has the expertise to meet your specific LSR coloring requirements. Whether you need medical-grade colorants, standard shades, or precise color matching, our team can help determine the best solution for your application.
Contact our engineers today to discuss your LSR coloring needs and receive detailed specifications for our available color options.