Post Office Sponge Strip
At Advanced Seals & Gaskets Ltd, we manufacture a wide range of specialist sponge strips, including the distinctive Post Office Sponge, also known as orange open cell natural sponge. This material is produced in blocks of various sizes and thicknesses up to 80mm, depending on density. Blocks can be split into sheets or laminated to create continuous lengths or rolls. Thicknesses start from just 1.5mm, and strips can be cut from 4mm width up to 50 meters in length, depending on application requirements.
By using customer samples, drawings, or specified dimensions, we produce made-to-measure Post Office sponge strips with precision, using bandsaws, strippers, log cutters, or presses depending on strip size and volume. In-house production ensures consistent quality, competitive pricing, and quick turnaround times. During conversion, we can laminate layers for non-standard thicknesses, supply plain strips, or laminate with self-adhesive foils or other materials for bespoke applications.
Product Enquiry
For information on Post Office Sponge Strip please complete the following quick enquiry or call us on +44(0)1384 252555.
Key Characteristics of using Post Office Sponge Rubber
- Colour: Bright orange
- Structure: Open cell (fine or medium)
- Density: 140 – 600 kg/m³
- Temperature Range: -40°C – +80°C
- Tensile Strength: 0.23 – 1.2 N/mm² (varies by density)
- Elongation at Break: 455% – 817% (varies by density)
- Resistances: Not resistant to ozone, acids, alkalis, oils, or fats
- Flammability: Highly flammable
Full technical data sheets are available upon request or via our online materials portal.
What are Post Office Sponge Strips?
Post Office sponge strips are typically supplied as cut lengths or continuous rolls for use in a variety of applications. They function similarly to gaskets, providing:
- Sealing between uneven surfaces
- Gap filling
- Anti-vibration and acoustic insulation
Manufactured from high-quality natural rubber, the material is available in different densities (160 – 600 kg/m³) and pore sizes, creating options from very soft to firm strips. Its bright orange colour and visible open-cell structure make it highly absorbent, ideal for holding liquids. Historically, this sponge was used in post offices to moisten stamps, illustrating its high absorbency and flexibility.
Why use Post Office Sponge Strips?
Post Office sponge strips are used similarly to other sponge gaskets and tapes, providing:
- Gap filling
- Vibration, noise, and rattle reduction
- Air, dust, and moisture sealing (under sufficient compression)
Although not resistant to oils, acids, or alkalis, these strips are ideal for wet applications, packaging, labelling, and vacuum lifting seals. The material can be split, laminated, or converted into a variety of finished products for custom applications, with options in density, firmness, and pore size to meet specific performance requirements.
Benefits of using Open Cell Natural Sponge Rubber
- Excellent abrasion resistance
- Soft, flexible material that seals around complex or uneven surfaces
- An open cell structure allows water absorption.
- Excellent recovery after repeated compression
- Good tear resistance
Other Grades of Sponge Materials Available
In addition to Post Office sponge, Advanced Seals & Gaskets offers a variety of other sponge materials:
- EPDM: Medium, firm, semi-open cell, high-temperature grades
- Neoprene: Flame-retardant, medium, firm grades
- Silicone sponge
- Polyurethane sponge
- Open Cell Natural Industrial Sponge
Advantages of Using Post Office Sponge Strips
Post Office sponge strips offer numerous advantages for both industrial and commercial applications:
- Available in soft or firm grades for tailored performance
- An open cell structure allows water absorption, perfect for wet applications such as packaging, paint pads, or vacuum lifting.
- Excellent compression recovery, ideal for repetitive loading and distortion applications
- Available in sheet sizes up to 2120 x 920mm and thicknesses up to 80mm, which can be converted into strips, rolls, or tapes
- Can be coated with foils or adhesives for added functionality
These properties make Post Office sponge strips highly versatile, whether for protecting goods, sealing gaps, or absorbing liquids, and they remain a trusted solution in packaging, construction, and industrial applications.
Please contact us using the form below or by calling us on +44(0)1384 252555.