Gelled or hardened Adhesive in nozzle. Adhesive can harden in the nozzle at 70°F in about 5-7 minutes. As the air temperature increases, gel time is shorter.

Too cold for adhesive to flow.

Surface is crusting

Obstruction in nozzle or on outlet of cartidge

Insufficient air pressure to the pneumatic tool.

Replace mixing nozzle.

Keep material in heated storage area: Store Epoxy at 45°F-90°F; store Acrylic at 32°F-80°F.

Remove nozzle, dispense small amount of material, then replace nozzle.

Change to new nozzle or remove obstruction from cartridge outlet.

Set air pressure at 80-100 psi.

Temperature of adhesive is too low.

Too little adhesive applied.

Increase temperature.

Increase pressure or nozzle size. Be sure problem nozzle is clear.

Moisture in substrate is evaporating.

Air leaking into pump.

Cavitation of pump.

Dry stock or lower application temperature.

Replace seals and/or pump.

Incrase supply of molten adhesive (use premelter or increase wattage).

Temperature too low.

Inadequate adhesive.

Cavitation of pump.

Increase temperature.

Increase pressure or nozzle size.

Consider selecting an alternative adhesive.

Temperature of adhesive of adhesive is too high.

Excessive exposure to air.

Reduce Temperature

Keep pot covered at all times

Nozzle too far from substrate.

Low pressure.

Temperature of adhesive too low.

Poor machine timing or alignment.

Hot melt has exceeded pot life

Move nozzle closer

Adjust pressure

Increase temperature

Adjust timing or alignment.

Flush system and refill with fresh adhesive.

Temperature too high.

Hot melt charring on side walls.

Air oxidizing hot melt.

Poor stability of hot melt.

Lower Temperature in tank.

Increase compression time.

Correct compression

Decrease temperature.