Post Office Sponge Washers
Thousands of washers are manufactured daily by Advanced Seals & Gaskets Ltd, using a variety of materials including standard sponge, foam, and rubber, as well as specialist materials like Post Office Sponge—a bright orange, open-cell natural sponge. Post Office Sponge is supplied in blocks of varying sizes and thicknesses up to 80mm, depending on density. These blocks can be split down to as little as 1.5mm and converted into a wide range of finished products, including Post Office Sponge washers.
Our washers are produced on-site using customer drawings or measurements, ensuring the final product meets exact specifications. Depending on size and quantity, one of our presses or CNC machines can be used to manufacture the washers, from one-off samples to large batch runs. On-site conversion ensures that Post Office Sponge washers can be supplied in a plain or self-adhesive finish, either loosely packed or kiss-cut on rolls for efficient 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: 140–600 kg/m³
- Temperature Range: -40°C to +80°C
- Tensile Strength: 0.23–1.2 N/mm² (depending on density)
- Elongation at Break: 455–817% (depending on density)
- Resistance (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?
Post Office Sponge washers are flat rings with an outer diameter (OD) and inner diameter (ID), cut from blocks or sheets of material. They are placed between surfaces to create a level surface, act as spacers, seals, or distribute pressure when tightening nuts and bolts.
Post Office Sponge is made from high-quality natural rubber, available in densities from 160kg/m³ to 600kg/m³. The sponge comes in a range of pore sizes, providing options from very soft to firm materials suitable for different applications. Its bright orange colour and open-cell structure allow it to absorb liquids, originally used in post offices for moistening stamps before self-adhesive versions were introduced.
Why Use Post Office Sponge Washers?
Due to its open-cell structure, Post Office Sponge is ideal for wet applications, labelling, packaging, and even vacuum lifting seals. While it is not resistant to oils, acids, or alkalies, it can effectively seal against air, dust, and moisture when sufficient compression is applied.
Like other block foams, Post Office Sponge can be split into sheets or converted into various finished products, including washers. By selecting the appropriate density and pore size, these washers can be customised to provide the required compression and moisture absorption for each application.
Benefits of Using Open Cell Natural Sponge Rubber
- Excellent abrasion resistance
- Soft and flexible for sealing uneven or complex surfaces
- An open-cell structure allows water absorption.
- Strong recovery after 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 from Post Office Sponge offer a range of advantages. Available in soft or firm variants, the open-cell structure allows them to be used in wet applications, where water absorption is needed, such as packaging that protects goods from impact or liquid damage.
The sponge retains moisture, making it suitable for reusable applications such as paint pads, rollers, and floats for plastering or tiling. Post Office Sponge washers are manufactured in various thicknesses and provide excellent compression recovery, even under repetitive loading. When compressed sufficiently, the open-cell structure behaves like a closed-cell material, effectively sealing against dust, air, and, to some extent, moisture.
Please contact us using the form below or by calling us on +44(0)1384 252555.