Working With PVA Glues
PVAs (polyvinyl acetates) are the adhesives many of us are most familiar with; the white glue we used as children belongs to this group. They are essentially emulsions of plastic in water and have many properties useful for woodworking – they are one part, flow smoothly and spread easily, cure within 24 hours and clean up readily with water. Here are some general guidelines for successfully working with them.
What is the clamping time for PVA glues?
PVAs should be clamped for 30 to 90 minutes, depending on ambient temperature and humidity.
What is the open assembly time for PVAs?
Open assembly time is the window between applying adhesive to the substrates and clamping them together. For PVAs, it’s typically 10 to 20 minutes, depending on the brand and conditions.
What is the best way to clean up squeeze-out?
In our experience, the most effective strategy is to remove partially cured glue while it’s a rubbery consistency, or to wait until the glue has fully hardened. Cleaning up with a damp cloth often has the effect of simply smearing glue around.
What is the “joint conditioning time”? How long is it?
Joint conditioning time (sometimes called “cure time”) is the period it takes for the adhesive to cure to full strength. 24 hours is typical. Avoid stressing assemblies until fully cured.
What is "glue creep"?
Creep refers to the parts of an assembly becoming misaligned due to wood movement or mechanical stress. A PVA glue-line is strong but not rigid. To avoid creep, be sure the components of your assembly are at the same moisture content and avoid using PVAs for assemblies under continuous stress, such as bent laminations.
Can I use PVA adhesives in cold conditions?
Only to a point. PVAs have a low temperature threshold (generally below 50°F/10°C) that prevents them from curing properly. The dried glue will have a powdery, chalky texture and no strength.
Is there such a thing as a waterproof PVA glue?
In our experience, there are no PVA adhesives that will withstand continuous submersion. There are a number of formulations that will withstand intermittent exposure to water, making them a good choices for outdoor projects or food-contact items such as cutting boards.