Common Defects in Pressed Plywood And How To Fix Them

Delamination (Layer Separation)

Delamination is where layers of veneer separate after they have been pressed. It is usually due to low hot press temperature, insufficient pressure or poor glue quality. The way to avoid it is changing press parameters, applying glue properly and controlling moisture of veneer before pressing.

Blisters or Air Pockets

Blisters are those raised bubbles on the surface of your plywood. This is often the result of air that is trapped when laying up the fabric, or because pressure is spread unevenly. This defect could be reduced by improving veneer stacking techniques and ensuring proper cold press pre-compression.

Uneven Thickness

Uneven thickness arises from inconsistent pressure or poorly aligned press plates. Consistent machine calibration and stable hydraulics allow for a uniform board thickness in the hot press block.

Glue Starvation (Weak Bond Lines)

This flaw appears when there is insufficient glue applied, or over-pressing squeezes out too much of the adhesive. Organizing glue spreader data, pressure regulation to improve equipment operation and keeping a minimum glue layer accurately.

Surface Roughness or Printing Marks

Dirty plates or too much pressure usually lead to rough surfaces or press plate marks. Regularly cleaning the press plates and adjusting the pressure reduces roughness on plywood to meet finishing and export standards.