What is the difference between the ANSI/HPVA Type I and Type II water-resistance specification?
Both of these tests are conducted using 6 by 6 birch laminates glued together to make three-ply plywood. The test for Type I is clearly more stringent than Type II, and involves boiling the glue bonds and testing the specimens while they are wet. Type I testing involves cutting the 6″ by 6″ assemblies into 1″ by 3″ specimens, boiling them for 4 hours, then baking the specimens in a 145F oven for 20 hours. They are boiled for an additional 4 hours, then immediately cooled using running water. The specimens are sheared while wet, and the bonds must pass certain strength and wood failure requirements to pass the Type I specification. Type II testing involves cutting the 6″ by 6″ assemblies into 2″ by 5″ specimens, soaking them for 4 hours, then baking the specimens in a 120F oven for 19 hours. This is repeated for a total of three cycles, and the bonds must not delaminate to pass the Type II specification.