| Walmark Corporation phone: (847)546-0400 fax: (847)546-1777 |
| SYMPTOM | CAUSE & CURE |
| When Spraying: | |
| Coating splatters and is uneven. | Too much fluid reaching tip. Reduce fluid pressure. Reduce fluid flow. Atomization pressure too low. Increase. |
| Narrow fan. | Improper choice of air caps. Inadequate air pressure. Check product data sheet for recommended pressures. Fluid pressure too low. Adjust pressure balance (air versus fluid). |
| Too light a spray pattern. | Not enough adhesive reaching the gun. Increase fluid pressure. Atomization pressure too high. Reduce. Spray gun moving too fast. Slow speed. |
| When Bonding: | |
| No bond or weak bond. | Light spray pattern (less than 80% coverage. Apply more adhesive Surfaces shiny. Sufficient coverage but spotty area contact with some scattered legging. Insufficient laminating pressure and/or maximum open time exceeded. Surfaces dull. No Legging. Excessive humidity causing moisture to condense on film. Dry adhesive longer (preferably with heat). Adhesive strips away from bonding surface. Contaminated surface (oil, dust, etc.). Clean or degrease surface. Dry spraying. Increase fluid delivery. Solvent odor in glue line. Severe legging. Insufficient drying. Dry adhesive longer (preferably with heat). Too heavy an application. Apply less. Soft, leggy bond. Conditions too cold. Raise area temperature. If waterborne adhesive is used, water may be entrapped. Increase drying cycle before bonding. |
| Warping. | Lamination is no longer flat. May be cupped or twisted. Unequal expansion of substrates due to heat/cold or moisture changes. Adhesive seldom at fault. Better choice of substrate needed. Angular feeding into nip roll. Feed horizontally into nip. |
| Blistering. | Round, domed area in field of panel. Tapping indicates localized delamination (hollow sound). Too heavy adhesive application. Reduce. Inadequate drying. Dry adhesive longer (preferably with heat). Low spots in core, resulting in no contact. Monitor core quality. |
| Edge or corner lift with legging. | Edges or end of bonded laminate raised slightly. Can be raised further by hand or knife. Too heavy adhesive application. Reduce. Inadequate drying. Dry adhesive longer (preferably with heat). Inadequate combining pressure. Increase. |
| Edge or corner lift with no legging. | Bond easily stripped from edge once started. spotty adhesion. Insufficient adhesive. Increase coating weight. Open time exceeded. Reduce. Inadequate combining pressure. Increase. Coarse edge in core with many depressions. Normal adhesive application unable to bridge gaps. Use better, less porous core material. |