You might be inclined to pour out milk once the expiration date stamped on the carton has passed. But don’t be so quick to toss out wood glue just because it has outlasted the manufacturer’s stated shelf life.
Most adhesives manufacturers stamp an official shelf life on their products to limit liability in case poor storage conditions cause product failure. The stated shelf life of wood glue typically is one to two years. However, the expected shelf life of many glues stretches well past those few years; for example, when stored correctly, the white or yellow wood glue (formally, polyvinyl acetate, or PVA glue) many DIYers and woodworkers keep on hand can last up to 10 or more years. These include popular glues such as Titebond® Original, Titebond II and Titebond III.
Bob Behnke, senior technical specialist at Titebond-manufacturer Franklin International, says that a dry, cool basement is an ideal place to keep wood glues. “The worst storage conditions allow freezing, then thawing and heat,” he explains. “Most wood glues are designed to withstand a minimum of five freeze/thaw cycles. With each cycle, the glue forms gels. Mixing easily breaks up these gels, but each subsequent freeze/thaw incident will make the gels more difficult to disperse.”
With time, you won’t be able to break up the gels at all, and the glue will remain solid. Heat also can cause the polymer to clump and gel.
How will you know if your glue has gone bad? “If it pours, it’s probably good,” says Behnke. If the glue has thickened, shake it vigorously by firmly tapping the bottle on a hard surface until the product is restored to its original form. You also can add up to five percent water to water-based glues (such as PVA glues) to thin the product. If the glue comes out stringy or pasty or wants to stick to itself rather than to the wood, it’s probably past its prime. If Titebond II turns orange, it’s time for a new bottle.
Additional information on calculating the shelf life of a given bottle of Titebond glue and related subjects is available in the Titebond online FAQ section. Here’s hoping you enjoy a long and productive working relationship with your next bottle of Titebond wood glue.