Hot melt stringing, char, fuming, or poor adhesion are common issues that can arise while working with hot melt adhesives. Thankfully, these issues are typically an easy fix. Please refer to this guide if any of these issues occur during your production.
- Possible Causes
- Suggested Solutions
Charring of Adhesive:
| Temperature too high in tank. | Lower the temperature in the tank. |
| Hot melt charring on sidewalls of tank. | Keep the tank filled 1” from top. |
| Air oxidizing hot melt. | Keep tank covered. |
| Contaminates in hot melt. | Cover tank and keep cartons closed/covered. |
Stringing/Webbing:
| Running temperature too low. | Raise temperature. |
| The substrate temperature is too low. | Pre-warm stock. |
| Timing or misalignment of flap. | Adjust equipment. |
| Poor shutoff nozzle. | Clean or repair nozzle shutoff. |
Poor adhesion:
| Adhesive mostly on one surface due to insufficient amount of adhesive or low running temperature | Increase pump pressure and/or raise temperatures |
| Adhesive on both surfaces but shows solidified “legs.” Caused by disturbing bond while adhesive is still in semi-molten state | Check compression, lower pressure and/or temperature. |
| Glossy surface appearance of hot melt, caused by poor or non-contact surfaces being adhered | Adjust pressure to keep glued surfaces together while hot melt cools. |
| Easy separation of bond. Usually, the result of improper selection of adhesive. | Call Technical Adhesives |
| Substrate change | Call Technical Adhesives |
Fuming or smoking:
| Poor heat control. | Use calibrated thermometer, reset thermostat. |
