The shelf life of all Polytek® liquid polyurethane products (rubber, plastic, foam) is six months from the date of shipment in unopened containers. After this time, the product may either cure improperly or may begin to solidify in the container.
Only purchase as much rubber, plastic, or foam needed for six months and use all of the product as soon as possible once opened (i.e., avoid keeping partially filled containers).
Exposure to Atmospheric Moisture & Water
A primary concern with liquid polyurethane components is exposure to atmospheric moisture and water, which can cause irreversible solidification, especially in Part A. Even if the product has not visibly hardened, it may have absorbed moisture which can cause foaming or an improper cure when the A and B components are mixed together.
Exposure can occur when the lid is left off of the product container, when the lid is placed back onto the container but not sealed well, when there is too much “headspace” in the container and when the product is exposed to water.
Here are some tips to help reduce the risk of moisture contamination:
- Always tightly reseal lids immediately after using the product (it is a good idea to also clean the rim of container after the product has been poured and before resealing the lid; you can use a solvent like ethanol/denatured alcohol on a clean paper towel).
- After dispensing the product, spray PolyPurge into the open container before replacing the lid. PolyPurge is a heavier-than-air dry gas blanket that displaces moist air. When the product is in drums, use Drierite® Cartridges.
- If there is a large amount of headspace in the container after dispensing, consider transferring the liquid to a smaller container (i.e., a clean metal or plastic container, excluding PVC) with less headspace. As always, use proper personal protective equipment when handling liquid components.
- Ensure that any fillers added to polyurethanes products are completely dry.
- Always work at room temperature (~77°F). Working in cold temperatures can slow the cure of the product (or may prevent the cure altogether) which may increase the likelihood of exposure to ambient moisture.
For best results, store liquid products indoors at temperatures between 60°F and 95°F. Long-term exposure to temperatures below and above this range may cause the product to act improperly. Polytek polyurethane products should always be at room temperature before use.