The shelf life of a material in its liquid state refers to how long it can sit on a shelf before it begins to lose its ability to function normally or sets up entirely in the container. You should know how long you can expect a material to last on the shelf to protect your material investment.

Relative humidity and temperature are variables that will affect the shelf life of Smooth-On rubbers, plastics, foams, Matrix products, epoxies, etc.

Shelf Life – Urethane Rubber, Plastic or Foam In Unopened Containers

Properly stored in a low humidity environment and at room temperature (73°F/ 23°C), urethane rubber, plastics and foams will have a shelf life of 1 year from date of manufacture in unopened containers.

Shelf Life – Urethanes After Containers Have Been Opened

The shelf life of unused product in containers that have been opened depends on exposure to ambient moisture in the air. The Part A side (Yellow Containers) is the moisture sensitive side of urethane compounds, and liquid material exposed to high-humidity environments can become moisture contaminated in a matter of hours. This moisture contamination may result in the urethane system bubbling or foaming when Part A is mixed with Part B.

Urethane Rubber – Unused Part A product exposed to humidity will begin to turn from liquid to solid in as little as a few hours. Part A exposed to relatively low levels of humidity will last two to three months in the container before showing signs of moisture contamination.

Limited Shelf Life Of Urethanes – What Can You Do?

Make sure you securely seal the Part A container immediately after dispensing each time.

Your Best Bet – If using urethanes, use what remains as soon as possible once containers have been opened.

Extending The Shelf Life Of Unused Urethanes – After dispensing Part A into a measuring container, spray XTEND-IT Dry Gas Blanket (available from Smooth-On or your Smooth-On distributor) into the container before securely resealing.

XTEND-IT will effectively double the shelf life of the remaining product by neutralizing any moisture-laden air that remains in your container. Follow directions before using.

Nitrogen will have the same effect, but is usually only available in large cylinders; very cost effective, but suitable only for industrial or production environments.

Shelf Life -Silicone Rubber

Properly stored at room temperature (73°F/ 23°C), silicone rubber will have a shelf life of 6 months from date of manufacture as determined by the lot number that can be found on the label of Part A or Part B. You can contact Smooth-On with these numbers to determine when the product was made.

Important – Elevated temperatures will drastically reduce the shelf life of silicone rubber. For example, silicone rubber stored at 80°F / 27°C will have a shelf life of about six months. Material stored at 100°F / 38°C will have a shelf life of about two months.

Shelf Life – Polymer Modifiers for Gypsum & Concrete

DuoMatix G, C and Matrix NEO – Properly stored at room temperature
(73°F/ 23°C), Matrix products will have a shelf life of 1 year from date of manufacture as determined by the lot number that can be found on the label of the liquid latex componenet. You can contact Smooth-On with these numbers to determine when the product was made.

Important – The latex component of the Matrix products must not be exposed to temperatures below 35°F / 1.7°C. Product that was allowed to freeze is no longer usable and should be disposed of.

Shelf Life – Rubber / Plastic Accelerators, SO-Strong Color Tints, Silc Pig Color Pigments and other accessories – at least 1 year from date of manufacture.

Shelf Life – Epoxy Adhesives – One year from date of manufacture.

Shelf Life – Powder Fillers 
– at least 1 year from date of manufacture.

Important: Keep powder fillers dry.

When Was A Material Manufactured? After locating the lot number on the label of Part A or Part B. You can contact Smooth-On with these lot numbers to determine when the product was made.