What does the term "shelf life" of a product mean?

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, duoMatrix™ products, epoxies, etc.

Use the guide below to determine the shelf life of a specific material.

Urethane Rubber, Plastic or Foam (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.

Urethane Rubber, Plastic or Foam (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.

What Can You Do?

When using urethanes, use what remains as soon as possible once containers have been opened. Make sure you securely seal the Part A container immediately after dispensing each time.

Extending The Shelf Life Of Unused Urethanes – After dispensing Part A into a measuring container, spray XTEND-IT Dry Gas Blanket 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.

Related How-To: Extending the Shelf Life of Urethane Rubber and Resin

Silicone Rubber (Unopened Containers)

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.

Release Agents (Aerosol)

Aerosol Release Agents have an official shelf life of one year from date of manufacture. In practice, however, we have found the shelf life of aerosols to be longer as long as the can remains pressurized and stored at 73°F (23°C).

Sealers and Release Agents (Liquids)

Liquid sealing and release agents have an official shelf life of one year from date of manufacture. In practice, however, we have found the shelf life of liquid sealing and release agents to be longer as long as the container is kept tightly sealed and stored at 73°F (23°C). After opening, product that is not adequately resealed can evaporate.

Polymer Modifiers for Gypsum & Concrete

duoMatrix™ and Forton™ systems when properly stored at room temperature (73°F / 23°C), 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 component. You can contact Smooth-On with these numbers to determine when the product was made.

Important: The latex component of these 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.

Rubber & Plastic Accelerators, Colorants, and Other Accessories

At least 1 year from date of manufacture.

Epoxy Adhesives

One year from date of manufacture.

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.

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Disclaimer
This FAQ article is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Safety Data Sheets (SDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.