Post Office Sponge Washers

Post Office Sponge Washers

Post Office Sponge Washers

Thousands of washers are manufactured by Advanced Seals & Gaskets Ltd on a daily basis, not only using the standard sponge, foam and rubber materials,but also other unique and specialist materials such as “Post Office Sponge” or orange open cell natural sponge. Post office sponge is manufactured in blocks of various sizes and thicknesses up to 80mm, which vary depending on density which we can split down to as little as 1.5mm thick and convert into a range of finished products including washers. Post Office Sponge washers are manufactured on-site using drawings or measurements provided by our customers, to ensure the final product is to their exact specification. Depending upon the size and quantity of washers required, one of many presses or CNC machines can be used to manufacture the final product - from one off samples to multiple thousand batch runs, we have a machine designed to quickly and accurately produce perfectly formed post office sponge washers everytime. On-site conversion facilities means we can quickly use blocks of stock material to produce post office sponge washers in a plain or self-adhesive finish, loosely packed or kiss cut on rolls for ease of use and application.

Product Enquiry

For information on Post Office Sponge Washers please complete the following quick enquiry or call us on +44(0)1384 252555.

    Product Specification & Key Characteristics

    • Colour: Orange
    • Structure: Open cell (fine or medium)
    • Density: 140 to 600 Kg/m3
    • Temperature Range: -40ºC - +80ºC
    • Tensile Strength:  0.23 N/mm2 - 1.2 N/mm2 approx (vary between densities)
    • Elongation at Break:   455% - 817% (vary between densities)
    • Resistances (Ozone/Acids/Alkalis/oils/fats/solvents): Not resistant
    • Flammability:  Highly flammable

    Full technical data can be supplied upon request,
    or downloaded from our online portal.

    What are Post Office Sponge Washers?

    Orange open cell Sponge Washers  are  a flat ring with an outer diameter (OD) and inner diameter (ID) measurement, cut from a sheet of material which is placed between two  surfaces creating a level surface, acting as a spacer, seal  or between nuts and bolts to spread the pressure when tightened.  Post office sponge is manufactured using high quality natural rubber, and available in a range of densities from 160kg/m3 to 600kg/m3, with a choice of pore sizes creating a selection of very soft or very firm materials each suited for use in different applications.   Orange open cell natural sponge is recognisable by its bright orange colouration and the visible cell structure which is designed to be absorbent to hold liquids within it (you may have seen this sponge in the post offices on which they would moisten stamps before the self adhesive backed ones were introduced!).

    Why use Post Office Sponge Washers?

    As Post Office sponge is not resistant to oils, acids or alkalis, these washers are limited for use and unsuitable in certain industrial or automotive applications, however perfect for wet applications, labelling, packaging and even to create vacuum lifting seals. Open cell post office sponge washers can also be used as air, dust to some extent moisture seals when under enough compression to cause the cells to squash down enough to stop anything passing through.

    As with many other types of block foam, post office sponge can be split down and supplied as sheets, or further converted into a range of finished usable products including washers.  Post office sponge has been developed so that it can be produced in a choice of densities, pore sizes and firmness in order for it to be utilised in a wide range of applications depending on the amount of compression and moisture absorption required.

    Benefits of Using Open Cell Natural Sponge Rubber

    • Good abrasion resistance
    • Soft and flexible to seal around uneven or complex shapes
    • open cell structures also allow for water absorption
    • Excellent recovery following repeated compression
    • Good tear resistance 

    Other Grades of Sponge Materials Available

    • EPDM - medium, firm, semi-open cell, high temperature
    • Neoprene - FR, medium, firm
    • Silicone
    • Polyurethane
    • Open Cell industrial sponge

    The Advantages of Using Post Office Sponge Washers

    Washers made using post office open cell natural sponge offers numerous advantages, available in a choice of soft- feel or very firm materials with an  open cell structure allowing the washers to be used in wet applications for water absorption for example in within packaging applications where these components help protect goods from impact damage or liquid spillages,whilst allowing for the circulation of moisture and gas when the application requires it.

    As this material catches liquid and holds it - it’s perfect for applications which then re-use the retained moisture such as paint pads and rollers, or floats used for plastering and tiling, etc.  Post office sponge washers can be manufactured in a range of thicknesses, all offering excellent compression recovery particularly when it’s used  for repetitive loading and distortion applications such as packaging and vacuum lifting.  When subjected to enough pressure, the open cell structure in these washers will compress enough to behave like a closed cell material where they can seal against the ingress or dust, air and to some extent moisture.

    Have a Question About Post Office Sponge Washers?

    Please contact us using the form below or by calling us on +44(0)1384 252555.