SATRA increases durometer range

An Asker C module is now available in SATRA’s family of durometers.

The range of SATRA durometers has grown with the addition of an ‘Asker C’ module that can be fitted to its popular modular durometer system. Incorporating a stand, the STD 639 instrument is available in either analogue or digital form, and can be used for testing to SATRA TM205:2016 – ‘Hardness of rubber and plastics – durometer method’.

Asker C has become a popular scale in the footwear industry to assess soft foamed materials used in footbeds (also known as ‘insocks’ or ‘inlaysoles’), as well as some of the softer midsole materials, including polyurethane (PU) and ethylene vinyl acetate (EVA).

In shoe solings, hardness is very important because it largely determines the ease of flexing and underfoot comfort. Softer (lower hardness) materials are easier to flex and compress, but are not necessarily always more comfortable. While softer materials offer more cushioning, they also offer less ground insulation, unless they are quite thick. If a thin sole is too soft, prolonged walking on hard or uneven ground can be uncomfortable.

By contrast, a hard sole (for instance, resin rubber or sole leather) can sometimes be comfortably flexible and ground insulating at low thickness. Therefore, appropriate hardness is very dependent on sole thickness, in order to balance flexibility with cushioning and ground insulation.

 

Publishing Data

This article was originally published on page 46 of the September 2017 issue of SATRA Bulletin.

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