Whilst raw rubber compound has a shelf life of just weeks or months, vulcanised rubber will last at least 5 years – much longer, in many cases. In order to keep your finished rubber products in good condition and retain the properties that the material was selected for, the following steps should be taken:
Temperature
Storage temperature should be below 25°C, ideally below 15°C; temperatures exceeding 25°C may accelerate deterioration sufficiently as effect service life of the product. Low temperature should not affect rubber products permanently, but care should be taken when handling materials to avoid distortion, and when taken from low temperatures into usage, the product should be approximately 30°C in temperature before being placed in service.
Humidity
Moist conditions should be avoided, and therefore storage methods should be chosen which eliminate the risk of condensation. The relative humidity of the atmosphere in storage should be less than 70% or, if polyurethanes are being stored, less than 65%.
Light
Product should be protected from light, particularly lights with a high level of ultra-violet such as direct sunlight and strong artificial lighting. It is recommended that any windows be covered with a red or orange coating/screen.
Radiation
Products should be protected from all sources of ionising radiation.
Ozone
Ozone is particularly damaging to rubber and therefore storage rooms should not contain any equipment that can generate ozone.
Deformation
Rubber should be stored free from superimposed tensions and compressive stresses or other causes of deformation. It is advisable that rings of large internal diameter are formed into three equal superimposed loops so as to avoid creasing or twisting. It is not possible to achieve this condition by forming just two loops.
Contact with liquid and semi-liquid materials
Rubber should not come into contact with liquid or semi-liquid materials or their vapours at any time during storage, unless these materials are an integral part of the product or the manufacturer’s packaging. When rubber products are received coated with their operational media, they should be stored in this condition.
Contact with metals
Certain metals and their alloys (in particular, copper and manganese) are known to have deleterious effects on some rubbers. Rubber should not be stored in contact with such metals except when bonded to them but should be protected by wrapping in or by separation with a layer of suitable material.
Contact with dusting powder
Dusting powders should only be used for the packaging of rubber items to prevent blocking, and the minimum quantity to prevent adhesion should be used. Any powder used should be free from any
constituent having a deleterious effect on the rubber or the subsequent application of the rubber.
Contact between different products
Contact should be avoided between products made from rubbers of different compositions, including products differing only in colour.
Products with rubber-to-metal bonds
The metal part of such products should not come into contact with the rubber of other products. Any preservative used on the metal should be such that it will not adversely affect the rubber or the bond.
Proofed fabrics and rubber sheeting
Proofed fabrics and rubber sheeting less than 1m2 in area or less than 2m in length should be stored flat and with the layers interleaved with a suitable material. Longer lengths and larger areas should be stored rolled and with layers interleaved with a suitable material.
Rotation of stock
Products should be issued from stores in strict rotation so that the products remaining in store are those most of most recent manufacture.
Recommended shelf life
| Material | Abbreviation | Life Group | Initial Storage | Extension Storage |
|---|---|---|---|---|
| Polybutadiene | BR | A | 5 years | 2 years |
| Natural | NR | A | 5 years | 2 years |
| Polyisoprene | IR | A | 5 years | 2 years |
| SBR | SBR | A | 5 years | 2 years |
| Polyurethane | AU, EU | A | 5 years | 2 years |
| Nitrile | NBR | B | 7 years | 3 years |
| Nitrile/PVC | NBR/PVC | B | 7 years | 3 years |
| Carboxylated | XNBR | B | 7 years | 3 years |
| Hydrogenated nitrile | HNBR | B | 7 years | 3 years |
| Epichlorohydrin | CO, ECO | B | 7 years | 3 years |
| Acrylic | ACM | B | 7 years | 3 years |
| Neoprene | CR | B | 7 years | 3 years |
| Butyl | IIR | B | 7 years | 3 years |
| Bromobutyl | BIIR | B | 7 years | 3 years |
| Chlorobutyl | CIIR | B | 7 years | 3 years |
| Chlorinated polyethylene | CM | C | 10 years | 5 years |
| Chlorosulphonated polyethylene | CSM | C | 10 years | 5 years |
| EPM, EPR | EPM | C | 10 years | 5 years |
| EPDM | EPDM | C | 10 years | 5 years |
| Fluorocarbon (Viton) | FKM, FPM | C | 10 years | 5 years |
| Silicone | Q, FQM, PQM, PVQM, MQ, VMQ | C | 10 years | 5 years |
Initial storage
The maximum period, starting from the time of manufacture, for which a rubber product, appropriately packaged, may be stored under specific conditions before a sample needs to be inspected or re-tested.
Extension storage
The period for which a rubber product, appropriately packaged, may be stored after the initial storage period, before further inspection and re-testing is necessary.
