Within the rubber family there are many different polymer types, ranging from the natural rubber that is tapped from rubber trees, through to synthetic rubbers that are derived from crude oil and other chemicals. They all have different strengths and weaknesses and there is not one single ‘magic rubber’ that does everything optimally, so it is vital to understand what the best polymer type is for any given application. 

Once the polymer type has been identified, the required operational parameters may dictate whether its performance needs to be formally defined as part of a specification. For example, if a particular level of chemical or temperature resistance is needed, or tensile strength value must be met, this aspect of the ‘rubber quality’ will be designed to meet those targets and, if tested against those requirements, it becomes known as a ‘specification grade’. Such a rubber spec may be unique to a customer, or it may meet an industry or international standard such as ISO, DIN, ASTM, etc.

Alternatively, a general purpose – or commercial grade – of the polymer choice may be suitable for the application. In this respect, properties such as chemical resistance, compression set and tensile strength will be lower – but in many cases will provide a suitable rubber quality for many products.