Albert F. Shore developed the measurement device called a durometer in the 1920s to measure material hardness. As a result of the Shore ratings, the terms hardness and durometer became interchangeable. Many pad print pad manufacturers color code the standard durometers by adding pigment to the silicone itself or by coloring the pad base. The following chart shows the durometer range for each silcone material (color) we typically recommend:
Blue 10 – 60
White 20 – 65
Red 30 – 75
The harder the pad, the higher the Shore durometer rating. Three basic pad durometers are standard in the industry and cover most applications. Custom pad durometers are also available through most pad suppliers. We suggest you invest in a durometer gauge, valuable for all pad printers for determining pad hardness and quality control of pads in rotation. This simple tool is available through silicone-rubber suppliers and many general-service dealers in the screen printing and pad printing industries.
Choosing the proper pad hardness for a job is often a combination of experimentation and experience. As a general rule, the harder the pad, the better the performance, the longer the pad life. But hard pads may be impractical in some applications. Here are some guidelines for durometer selection and maintenance:
- Use softer pads when printing on heavily contoured surfaces or on fragile items.
- Use a softer pad if the power of your machine can’t compress the pad sufficiently to achieve a satisfactory rolling action.
- Use hard pads for textured surfaces, or printing an image in a recessed area where the pad must roll over a “step”.
- Use hard pads in a pad “nest” where a number of pads are spaced with small gaps (for example, printing computer keyboards).
- Consider a special pad for printing on abrasive substrates and textured finishes. Example applications include automobile control arms like turn-signals and windshield-wipers, when the pad must resist the abrasive nature of the substrate.
- Avoid using pads of different durometers on the same application. The thickness of the ink deposit will vary on the substrate.
Custom Pads – Custom Service
Confused about durometer? Need help selecting pad durometer for a custom job? We have a full pad department to help and we don’t charge for phone calls! Click Cylindrical Printing Padsor call 800-272-7764 for our undivided attention. We are here to help you!