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BOND TROUBLESHOOTING<br />
Common bonding problems and solutions are detailed below<br />
Defect Cause Solution<br />
Open Glue Joint • High or low wood moisture content<br />
• Joint surface too rough<br />
• Excessive or insufficient adhesive<br />
• Adhesive cured before construction<br />
• Insufficient pressing time<br />
• Excessive or insufficient pressure on joint<br />
Sunken Joint • Bonded panel machined to soon after<br />
construction<br />
Follow recommended parameters for<br />
each type of joint to be bonded.<br />
Leave panel 16 to 24 hours after pressing,<br />
before machine<br />
Telegraphing • Non-uniform adhesive coating Accentuated through thin faced or high<br />
gloss finish laminates<br />
Visible Glue Line • Non-uniform edge machining Reduce quantity of adhesive on joint<br />
Blistering (No adhesion<br />
between layers)<br />
• Skips in adhesive spreading<br />
• Pre-curing or pre-drying of glue line<br />
• Surface inactivation or oily wood<br />
Assemble joints immediately after adhesive<br />
application.<br />
Reduce the quantity of adhesive.<br />
Follow recommended parameters<br />
for each type of joint to be bonded.<br />
Prepare surface with fine grade sand<br />
paper or clean surface with organic<br />
solvent e.g. Alcohol<br />
Panel Warping • Construction imbalance Check thickness, density, moisture, species<br />
of components and their compatibility<br />
Component Thickness<br />
Variation<br />
• Component moisture variation Equalise component moisture content<br />
before assembly.<br />
32 <strong>GLUES</strong>, <strong>ABRASIVES</strong>, <strong>SCREWS</strong>
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