Hotmelt Adhesive Trouble Shooting Guide
| Purchasing Hotmelt Adhesives can be challenging – especially when it comes to technical details. To help simplify the process, we have developed a Hotmelt Adhesive Troubleshooting Manual that addresses the most common issues faced during application, particularly in edgebanding. Whether you are dealing with adhesion problems, stringing, or inconsistent bonding, this guide is designed to help you identify and resolve issues quickly and efficiently. |
Critical Parameters for Good Hotmelt Adhesion
Generally speaking, good adhesion occurs when temperature, time, pressure, the amount of glue, and application speed are working in harmony. If either one of these parameters is compromised, bonding issues may occur. The following recommendations are important steps to ensure proper edgebanding adhesion to the board:
Technical Data Sheet and Safety Data Sheet
Each hotmelt comes with a Technical Data Sheet outlining temperature, opening time, application speed and other information. Please follow the recommended setting parameters.
The Safety Data Sheet provides important information about the safe handling of the product. Please follow the recommendation in the Safety Data Sheet.
You can download the data sheets for each product at ramsindustries.com
Temperature
Please follow the temperature range on the Technical Data Sheet for the hotmelt you are using. Avoid operating temperatures in excess of the top end of the recommended temperature range. Higher temperature is not a cure for insufficient adhesion!
The wrong temperature is often responsible for poor adhesion. Temperature probes in the glue pot may malfunction and deliver the incorrect temperature to the edgebander. We advise to use a digital thermometer and check the actual temperature of the hotmelt on the glue application roller and in the glue pot. Temperature should be measured in the center of the glue pot and glue application roller. Adjust the temperature accordingly, if there is a discrepancy between temperature setting on the edgebander and actual temperature reading.
Manual addition of hotmelt is often responsible for temperature fluctuation (as much as 40ºC/104ºF) resulting in poor adhesion. It is advisable to refill glue pots during breaks or start of the shift allowing the glue to get up to the required temperature. The glue pot should never run low before refilling as the hotmelt will burn (oxidation) causing poor adhesion.
It is advisable to store board and Edgebanding at room temperature for at least 24 hours before processing.
Pressure
The amount of pressure is adjustable on most machines and can be set to the ideal level. As the board passes through the pressure roller station, the Edgebanding is evenly bonded to the board. Pressure rollers must be kept clean at all times. Please remove any glue residue from the pressure rollers resulting in uneven pressure.
Amount of Glue
Uniformity and thickness of glue spread are very important. The glue spread should be thick enough to cover 90% of the board. 10% of open spots are acceptable. Please adjust the amount of glue when excessive hotmelt squeeze out occurs or the glue spread does not over the board appropriately. More glue is not the cure for insufficient adhesion!
Most glue application rollers wear out over time. Change the glue application rollers when the grooved pattern is too light avoiding insufficient glue amounts.
Hotmelt which is heated and cooled too many times will produce a weaker bond. We recommend flushing out older adhesive and replace it with fresh hotmelt. We also advise to reduce the heat of the glue pot whenever the edgebander is not being used for longer periods. Reducing the glue pot temperature during idle times will reduce burning/browning of the glue (oxidation).
Glue Pot Maintenance
We recommend to cover the glue pot at all times to minimize oxidation (browning/charring) of the hotmelt resulting in poor adhesion.
We also recommend to clean the glue pot regularly (once a month). Hotmelts tends to carbonize on the bottom and sides of the glue pot negatively affecting heat transfer to the glue. Sandblasting is the best way to clean a very dirty glue pot.
Glue pot and glue spreaders containing EVA hotmelt can be cleaned with solvent (e.g. Toluene from Home Hardware, RONA, Canadian Tire).
Application Speed Each hotmelt formulation is designed for a specific feed speed that the board runs through the edgebanding process. It is important that the edgebander can deliver the required feed speed that is outlined in the Technical Data Sheet. Processing edgebanding at a lower or higher than prescribed speed will decrease the adhesion quality.
✅ Edgebanding Adhesion Checklist
📄 Documentation
- Review Technical Data Sheet for temperature, open time, speed, and settings.
- Review Safety Data Sheet for handling guidelines.
- Download both documents from ramsindustries.com.
🌡️ Temperature
- Operate within the temperature range on the TDS.
- Avoid exceeding the upper temperature limit.
- Use a digital thermometer to verify glue roller & pot temperatures.
- Measure temperature at the center of the glue pot and roller.
- Refill glue pot during breaks or before shifts—never when low.
- Store boards and edgebanding at room temperature for 24 hours prior.
- Make sure that there is no cool draft since it can affect the glue temperature.
📏 Pressure
- Adjust pressure rollers to optimal level. Set the pressure rollers to accommodate the thickness of the edgebanding
- Clean rollers regularly—remove glue residue.
🧴 Amount of Glue
- Ensure glue spread covers at least 90% of the board.
- Adjust for excessive squeeze-out or low coverage.
- Replace worn glue rollers showing weak groove patterns.
- Flush old glue; use fresh hotmelt.
- Reduce glue pot heat during idle times to prevent oxidation.
- Make sure the board touches the glue roller.
- Is the shoe guide (skid plate) properly adjusted (distance between the shoe and the board should be 0.1mm
🧼 Glue Pot Maintenance
- Keep glue pot covered to avoid oxidation.
- Clean monthly—preferably via sandblasting.
- Use solvent (e.g., Toluene) for EVA hotmelt cleaning. The glue pot must be cold.
🚀 Application Speed
- Match feed speed to Technical Data Sheet specs.
- Avoid running too fast or too slow—impacts adhesion.
Edgebanding
- Ensure the Edgebanding is clean and dust-free
- Check for primer on the back – Matte/Chaulk = primer is present, shiny = insufficient primer
- Inspect the Edgebanding for warping or curling
| Symptom | Possible Causes | Corrections/Remedies |
| Poor adhesion | Incorrect temperature setting | Verify with digital thermometer and adjust to TDS range |
| Old or oxidized hotmelt | Flush and replace with fresh glue | |
| Insufficient glue coverage | Adjust glue amount to cover at least 90% of surface | |
| Adhesive on board and edgebanding | Application temperature to high | Decrease application temperature (where applicable) |
| Press time too short | Decrease machine speed | |
| Temperature resistance of hotmelt too low | Change to hotmelt with higher softening point | |
| Adhesive remains on substrate, pattern from the application roller is embossed on hotmelt | Application temperature is too low | Increase to specified hotmelt temperature per TDS |
| Insufficient pressure | Increase pressure and check for contact of pressure rollers | |
| Machine speed is too slow | Increase machine speed per Adhesive Technical Data Sheet (TDS) | |
| Open time of hotmelt may be too short | Increase application temperature or increase machine speed | |
| Excessive glue squeeze-out | Too much glue applied | Reduce glue spread to avoid waste and mess |
| Excessive pressure | Lower pressure settings | |
| Gaps or lifting at edges | Primer missing or uneven on edgebanding | Check underside for matte finish; replace if needed |
| Low room temperature of board or edgebanding | Store materials at room temperature for 24 hours before use | |
| Burnt or brown glue appearance | Overheating / oxidation of hotmelt in glue pot | Reduce idle temperature, clean glue pot, keep glue pot covered |
| Reusing glue too many times | Avoid repeated reheating cycles; use fresh glue regularly | |
| Uneven glue line or poor bond line | Worn glue roller | Replace roller if grooves are worn or uneven |
| Dirty or damaged pressure rollers | Clean rollers and ensure proper alignment | |
| Stringy or thick glue consistency | Glue temperature too low | Increase temperature to recommended level |
| Contaminated hotmelt | Clean glue pot and use fresh adhesive | |
| For PolyOlefine, we recommend 237.50 (no stringing formulation) | ||
| Adhesive remains on edgebanding | Poor wetting (spread of adhesive) of board surface due to insufficient heat or pressure | Increase pressure, temperature, and/or speed |
| Very apparent glue line on one side of the board | Board edge was not cut straight, glue roller not perpendicular to edgebanding | Check setup for squareness |
Author:
Markus Raves, RAMS Industries, Ltd.
Editor:
Tim Martin, Managing Director Sales, Jowat Canada Ltd.
