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Silicone rubber is an extraordinary material

With subtle alterations to its chemistry the changes in properties can produce material safe enough for baby bottle teats, and parts tough enough to withstand the demands of jet engines.

Primasil are the UK leaders in the formulation and mixing of HCR and Platinum-Cure silicone rubber, with each formulation customised to exactly meet our customers’ requirements. LSR is bought “off the shelf” from global suppliers, and our experts work closely with the customer to ensure the best fit possible.


The popularity of Liquid Silicone Rubber (LSR) in medical device manufacturing owes much to its biocompatibility and the excellent quality of production components. The reduced human contact during processing reduces the risk of contamination, especially when manufactured in a clean room environment.

It is typically supplied in two parts, one of which contains a curing catalyst. These are automatically mixed, along with colours and any other ingredients, as the material is pumped to a press.

 Our LSR datasheets here



High Consistency Rubber (HCR), or Heat Cured Rubber, also plays a big part in our silicone rubber manufacturing operations. Again a choice is available between platinum and peroxide curing.

 Our HCR datasheets here



The dangers of harmful bacteria and MRSA are now widely recognised. The food and healthare industries now demand materials thats can eliminate these dangers to provide a safe environment.

Primasil have developed "biosil", an independently tested anti microbial silicone rubber that actively breaks down the bacteria, killing the strain.

Being odour free, non toxic, and non leaching, biosil is ideal for all food and healthcare applications.

 Silicone Rubber has the following advantages:

  • Biocompatible and non toxic
  • Withstands common sterilization methods
  • Operating temperature range of -50ºc to +250
  • Hardness ranging from 10 to 90 Shore A
  • Can be pigmented to virtually any colour
  • Inherently flame retardant
  • Weather and ozone resistant
  • Electrically conductive or insulating



For medical applications, we often recommend platinum as the catalyst. Ideally suited for applications where strength, durability, long-life and non-reactivity with bodily fluids and skin are important. Platinum-cured products meet or exceed these global standards:

  • ISO 10993
  • US Pharmacopoeia Class VI
  • European Pharmacopoeia 3.1.9
  • FDA CFR177.2600
  • BfR and FDA Food Contact Regulations

Compared to peroxide-cured materials they have the following advantages:

  • Superior clarity
  • Smoother inner wall which results in less protein binding
  • No contamination from peroxide residues
  • Fewer extractables



Primasil can also provide medical peroxide-cured materials where required.