Adhesive Troubleshooting Guide

Select the type of adhesive you are facing problem with and click on the question to open our suggested solutions.

Problem Suggested Solution
Q.1. Adhesive mostly on one surface due to insufficient amount of adhesive or low running temperature. A.1. Apply heavier glue film thickness and/or raise temperature.
Q.2. Adhesives on both surfaces but shows “legs”. Caused by disturbing the bond while still in semi-molten state. A.2. Check compression, apply cooler, or use faster setting adhesive.
Q.3. Glossy surface appearance of hot melt. Caused by poor or non-contact of surfaces being adhered. A.3. Adjust pressure to keep glued surfaces together while hot melt cools.
Q.4. Easy Separation of bond. Usually a result of improper selection of adhesive. A.4. Try a more suitable product.

Problem Suggested Solution
Q.1. Temperature too high in tank. A.1. Lower temperature in tank.
Q.2. Hot melt charring on side walls of tank. A.2. Keep tank filled.
Q.3. Air oxidizing hot melt. A.3. Keep tank covered.

Problem Suggested Solution
Q.1. Overheating. A.1. Drain and flush system and lower temperature.
Q.2. Mixing of incompatible adhesives. A.2. Check with your Walmark representitive.
Q.3. Unstable hot melt (if repeated). A.3. Check with your Walmark representitive.

Problem Suggested Solution
Q.1. Running temperature too low. A.1. Raise temperature… however, too high a tempperature can affect heat stability.
Q.2. Stock temperature too low. A.2. Prewarm stock.
Q.3. Poor timing or misalignment of carton flap to applicator roll. A.3. Machine adjustment.
Q.4. Poor shutoff of nozzle. A.4. Clean and repair nozzle shutoff.

Problem Suggested Solution
Q.1. Nozzles clogged. A.1. Clean or repair nozzle.
Q.2. Remote nozzle in multitude nozzle set-up may be affected by pressure drop. A.2. Increase temperature or pressure slightly. Put larger orifice openings on remote nozzles. Melt down capacity of unit may be inadequate for demand. Raise temperature or add auxiliary pre-melter.

Problem Suggested Solution
Q.1. Poor heat control. A.1. Use calibrated thermometer, reset thermostat.
Q.2. Hot melt has poor heat stability. A.2. Reduce temperature to minimum needed for a good bond. Cover reservoirs or premelters whenever possible. Open pots almost always smoke. Use suction fan over pre-melter or reservoir and exhaust fumes to outside.

Possible Cause Suggested Solutions
Improper viscosity, solids, applications.
  1. Check if product has been diluted.
  2. Check if product has been stirred thoroughly before use.
  3. Check viscosity increase due to aging. Dilute if necessary.
  4. Check for excessive application, reduce if necessary.

Possible Cause Suggested Solutions
Improper viscosity, stock, compression.
  1. Check viscosity as above.
  2. Check for uniform application pattern.
  3. Check compression (too little or too much).
  4. Check for improper scoring which can cause springy flaps. May need faster, tackier adhesive
  5. Change stock or adhesive.

Possible Cause Suggested Solutions
Improper viscosity or stock.
  1. Check viscosity as above.
  2. Check compression
  3. Increase or decrease application as required.
  4. Change stock or adhesive.

Possible Cause Suggested Solutions
Q.1. Insufficient adhesive A.1. Increase amont of adhesive being applied.
Q.2. Porosity or sizing of substrate A.2. Improper adhesive. Contact sales representative.

Possible Cause Suggested Solutions
Q.1. Not enough adhesive A.1. Increase amoont of adhesive being applied.
Q.2. Open time is too long A.2. Increase machine speed.
Q.3. Ambient temperature is too hot A.3. Remedy temperature if possible or increase amont of adhesive.

Possible Cause Suggested Solutions
Q.1. Too much adhesive A.1. Reduce adhesive amount and or increase compression
Q.2. High humidity A.2. Reduce amount of adhesive being applied to compensate.
Q.3. Ambient temperature is too cold A.3. Attempt to maintain room temperature for adhesive and substrates.

Possible Cause Suggested Solutions
Q.1. Cold adhesive A.1. Raise temperature of adhesive/ environment.
Q.2. Adhesive contamination A.2. Ensure cleanliness of resevoir, nozzles etc.
Q.3. Adhesive build up in equipment A.3. Check and clean all equipment.

Glossy Appearance

Cause Remedy
Insufficient pressure. Increase pressure.
Prolonged open time. Reduce open time.

Adhesive On One Surface Only

Poor joint fit. Improve joint quality.
Cause Remedy
Prolonged open time. Reduce open time.
Precure of adhesive. Check wood moisture content or decrease assmembly time.
Inadequate pressure. Increase Pressure.

Spongy Looks Cellular

Cause Remedy
Foam in adhesive. Replace glue.
Inadequate pressure. Increase pressure.
Pressure removed too soon. Increase press time.


Cause Remedy
Adhesive, Stock and Surroundings Too Cold. Warm up plant (65oF) and Stock.

Blue-Black Stain On Hardwoods

Cause Remedy
Iron contamination. Check equipment for contact of adhesive bare iron.

Thick, Noticeable Glue Line

Cause Remedy
Poor fit. Check joint quality. Avoid hollow joints.
Inadequate pressure. Increase pressure.
Prolonged closed assembly line. Reduce assembly time.

Prominent Glue Line viewed in incident light.

Cause Remedy
Thick glue line. Improve joint quality.
Glue and finishing materials incompatible. Check with adhesive and finish suppliers.
Varying moitsture contents of wood at time of gluing. Check kiln schedule.
Oversanded (scoured). Cunsult abrasive supplier.
Sunken joints. Allow time for glued off stock to equalize before processing.


Cause Remedy
Unbalanced construction. Consult Bond Tech Rep.
Unbalanced finishing. Seal underside of panel.
Unbalanced moisture content of components. Bring all parts to equilibrium before gluing.


Cause Remedy
Dirt, chips, etc., on core or in adhesive. Keep laminating area clean.
Surface defects on core material. Clean and inspect cores before laminating.
Differential density in core. (e.g. lumber banded particleboard to core) Press at minimum safe pressure. Check thickness of band relative to core.

End Checking

Cause Remedy
Stock at too high moisture content when glued. Check kiln schedule.
Starved joints. Avoid hollow joints.
Wood not sized. Check kiln schedule.

Blisters (decorative laminate)

Cause Remedy
Variation in core caliper. Check Coating uniformity face and back.
Glue line skip. Check Coating uniformity face and back.
Localized pressure. Check Coating uniformity face and back.
Steam pockets. Reduce spread rate/press temperature.

Loose Veneers

Cause Remedy
Insufficient pressure due to extended closed assembly or core too dry. Reduce closed assembly time.
Poor bond but glue on both surfaces. Increase pressure.

Loose Corners

Cause Remedy
Insufficient pressures or press time. Increase pressures and/or press time.
Lumber bands under size. Make lumber bands same thickness as core.
Core edges undersize. Check caliper of edges to give less than 0.005″ variation.

Bond Tech Industries
for Your Adhesive Troubleshooting Needs?

Still facing problems?


  • This field is for validation purposes and should be left unchanged.