Written by Jody Muelaner
The correct storage of adhesives is essential. However, storage requirements vary considerably between the different types of adhesives. Some can be stored indefinitely without any special requirements, while others require refrigeration and will only last a few weeks.
For some adhesives, proper storage is critical. For example, the product may dry out or cure, making it impossible to use. What’s most concerning is that structural adhesives, if not stored correctly, may appear to function well when applied but not achieve their specified bond strength.
The typical storage requirements for a range of common adhesives are summarized below. These are examples only. It’s important to always check the manufacturer’s recommended storage for a specific adhesive by reading the label on the container.
- Emulsion adhesives, such as polyvinyl acetate (PVA), are water-based and form a bond as water evaporates. They must be stored in a sealed container that does not allow air circulation or evaporation. They should also be stored between 5° C (41° F) and 25° C (77° F). Under the right conditions, PVA will last for many years.
- Two-part epoxy resin is supplied in two containers: the resin and the hardener. When mixing a batch no hardener must get into the resin container. The containers should be properly sealed and stored at room temperature. Exposure to low temperatures, below about 13° C (55° F), should be avoided.
- One-part epoxy resin is supplied as a paste or within a pre-impregnated fiber mat (prepreg). It requires heat for effective curing, often applied in an autoclave. One-part epoxy and prepreg must be cold stored to delay curing and typically has a shelf life of just a few weeks.
- Cyanoacrylate adhesive, such as Superglue, cures when exposed to atmospheric humidity. It’s vital to void exposure to air during storage. The container should be tightly sealed and any air squeezed out of the container.
- Polyurethane adhesive also cures when exposed to humidity and should be stored in a tightly sealed container with as much air as possible squeezed out. Once opened, don’t expect PU adhesive to last more than a few weeks.
- Hot-melt adhesives are thermoplastics that can be melted. This means they are easy to store and should last for years with no special requirements.