Charring occurs when a hot melt adhesive is exposed to excessive heat for an extended period. This can lead to a darkening or burning of the adhesive, ultimately leading to downtime to purge the system. Factors such as temperature control, air exposure, and the type of adhesive used can all contribute to the risk of charring.
Hot melt adhesives have a specified operating temperature range, which should be listed on the product’s technical data sheet. Ensure your equipment settings and units (Celsius vs Fahrenheit) match the listed values. If you are experiencing charring and your settings all look good, it may be worth using an infrared thermometer to confirm your equipment is functioning correctly. (Request a TDS for any of our products here.)
Invest in high-quality adhesive dispensing equipment that provides consistent heat and minimizes fluctuations. Low-quality equipment may not maintain temperatures effectively, increasing the risk of overheating.
Only heat the adhesive as needed for your application. Avoid letting the adhesive sit in the heated reservoir for extended periods when the lines aren’t running.
Different types of hot melt adhesives are designed for specific applications and temperatures. Select an adhesive formulated to withstand the conditions of your particular project. For example, metallocene hot melts offer better pot stability and resistance to char formation than EVA hot melts when held molten for extended periods. Consult your adhesive supplier for recommendations tailored to your requirements — our team is available through adhesive technical support.
Schedule routine maintenance of your heating systems to ensure they are functioning properly. Clean tips and hoses regularly to prevent buildup that can lead to overheating and burning of the adhesive.
Preventing charring in hot-melt adhesives is crucial for maximizing uptime and ensuring efficient production. By monitoring temperature settings, using quality equipment, selecting the right adhesive, and implementing best practices, you can significantly reduce the risk of charring.
If char keeps showing up in your tank no matter what you adjust, it might be the adhesive itself. Request an Adhesive Analysis Kit and we’ll match a hot melt to your line speed, dwell time, and equipment.
