24/07/2026
Why Does the Adhesive Still Have a Strong Odor After Use ❓
When solvent-based adhesives are used in shoe production, the solvents in the adhesive must evaporate before the adhesive film reaches the proper condition for bonding.
If the oven temperature is too low, the drying time is too short, or the exhaust system is insufficient, the solvents inside the adhesive film may not be fully released. After bonding, these residual solvents can become trapped between the upper and the sole.
This may lead to:
A noticeable solvent odor in the finished shoes;
A stronger and more concentrated odor after packing;
Bubbles forming inside the adhesive film;
Normal initial bonding strength but reduced strength over time;
Adhesive being squeezed toward the edges and leaving visible glue marks.
What Oven Temperature and Drying Time Should Be Used?
For solvent-based shoe adhesives, the following ranges can be used as a starting point for production testing:
Recommended starting temperature: 45–60°C
Recommended starting drying time: 3–8 minutes
Please note that these values are only starting ranges for on-site testing.
The following principles can be used when making adjustments:
For heat-sensitive materials such as mesh, thin PU leather, and light-colored materials, start at 45–50°C;
For areas with a heavier adhesive coating, thicker materials, or highly porous materials, extend the drying time first instead of sharply increasing the temperature;
Adjust only one variable at a time, such as increasing the temperature by 5°C or extending the drying time by one minute;
The oven must have stable hot-air circulation and sufficient exhaust. Do not rely only on the temperature shown on the display;
Drying and heat activation should be treated as two separate processes. Do not blindly increase the temperature simply to speed up solvent evaporation.
A higher temperature does not necessarily remove solvents more effectively. If the surface of the adhesive film dries too quickly, it may form a skin that prevents the solvents inside from escaping.
Excessive temperature may also cause light-colored materials to deform, yellow, or shrink.
Recommendations for Odor Problems
Do not replace the adhesive immediately. Check the following factors in order:
Adhesive coating amount ➡️ actual oven temperature ➡️ drying time ➡️ hot-air circulation ➡️ exhaust efficiency ➡️ waiting time before packing ➡️ solvent system of the adhesive
Only when a new adhesive produces a noticeably lower residual odor under the same material, coating amount, and drying conditions can it be concluded that the adhesive itself provides a genuineimprovement.
