Which Elastomer Offers The Best Water Resistance?

In instances where a product or component is required to be water resistant, there are a number of different base elastomers which should be considered, with, as would likely be expected, a number of options available.

At White Cross Rubber Products Ltd, we supply both rubber sheet and rubber coated textiles for use in a number of situations where water resistance is a key characteristic of the product, including that for use as waterproof membranes and a range of other applications.

Which elastomers, however, offer the best water resistance?

As with the different properties of all base materials, you will find that certain elastomers perform better than others when it comes to water resistance and, whilst the properties of an elastomer can be improved through the inclusion of additives, it is important to develop an understanding as to which base offers the most suitable properties as a material in its own right.

When selecting an elastomer for an end product which must be water resistant, it is important to consider which offers the best impermeability to water, i.e. does not allow water to pass through.

White Cross Rubber Products Ltd use a core selection of 12 different elastomers for the manufacture of rubber sheeting, reinforced rubber sheeting and rubber coated textiles, and throughout the fulfilment of all orders and the production of our applied technology range, our specialist, experienced technicians are on hand to help inform decisions and to help make the research stage that little bit more straightforward. With regards to the elastomer which offers the best water resistance, a number of options are primarily available, however the most suitable material for any given product or component rests upon an initial brief and, perhaps more importantly, understanding the end use environment.

Please see below an overview and a comparison of our 12 most commonly utilised base materials based upon their water resistance properties rated ‘poor’ to ‘excellent’:

Please note: Whilst most main rubbers are outlined below, our capabilities and experience allow us to manufacture a much wider range of blends and formulations. The inherent characteristics of a polymer can be improved through the inclusion of additives, including the water resistance properties.

Elastomer Water Resistance
Butyl Excellent
EPDM Excellent
Silicone Excellent
Vamac Excellent
Viton Excellent
Hypalon Good
Natural Rubber Good
Neoprene Good
Nitrile Good
SBR Good
Thermoplastic Elastomer Good
Polyurethane Fair

Whilst initially faced with 12 elastomers which are used by ourselves as base materials for the production of products and components, it is clear that we see here five deemed to offer ‘excellent’ water resistance, these five being: Butyl, EPDM, Silicone, Vamac and Viton, however, more often than not when water resistance is the key trait and not more extreme properties, Vamac and Viton can be discounted as they are very expensive choices, with their excellent all round characteristics leading them to be considered ‘over engineered’ in water environments.

As such, looking at each of these three elastomers in more depth, it should offer a basic understanding as to their wider properties.

Butyl offers a very low gas and moisture permeability as well as excellent resistance to heat, ageing, weathering, ozone and chemical attack. Butyl is not, however, suitable for use in products or components where exposure to petroleum oils and fluids is likely. Common uses for butyl rubber sheet are usually in instances where excellent air, gas or liquid retention and resistance to environmental degradation is required such as in waterproof membranes and liners.

EPDM is widely regarded as one of the most versatile base elastomers and is often seen as the best choice when exposed to even the most aggressive of weather conditions. The relatively low cost of EPDM leads it to be a suitable and popular choice in many applications such as roofing membranes and window seals.

Silicone is often the elastomer of choice for those manufacturing for the medical, pharmaceutical or food processing industries, due to the fact that it is physiologically inert. One of the standout characteristics of Silicone is its stability in extreme temperature environments.

An additional consideration when rubbers for use in environments where water resistance is needed is whether they are suitable for drinking water applications.

In such environments, articles made of ‘purer’ EPDM and Butyl compounds are required. These compounds have been tested so that they have no odour, impart no taste and do not foster microbiological growth. Such compounds need to be certified to show that they are suitable, for example, WRAS approved in the UK and NSF in France.

When identifying the best base elastomer to use for any given product or component, it is important that specific requirements are analysed in-depth and considerations are made to a number of options, as outlined above. In many instances, the chosen material will end up being a compromise between factors such as the end usage environment and the financial cost of a given blend.

As one of the UK’s leading suppliers of rubber sheet, reinforced rubber sheet and rubber coated textiles, our team offer a wealth of expertise and capabilities which allow the manufacture of a specific blend or formulation to meet the exact specification of a project.

To speak with one of our expert technicians or to find out more information as to the specific water resistance of any one of our 12 commonly used base elastomers or to discuss in-depth a brief or product specification, we encourage you to call us on 01524 585200 or to email us on [email protected].