Why does my hot melt bead have bubbles?
Bubbles at the gun typically mean moisture in the tank or glue, or air pulled in through a damaged valve or fitting. Bubbles that show only on the board typically mean moisture in the board boiling off under the hot bead. Shoot a bead onto clean metal: if it is smooth there, the board is the cause.
Hot melt and hot equipment can cause burns. Follow your equipment maker’s safety manual and lockout steps; qualified personnel only. Call us for data sheets
Find the source
| What you see | Likely cause | What to try |
|---|---|---|
| Bubbles in the bead at the gun, on any surface | Moisture in the tank or in the glue | Keep glue sealed and dry, keep the lid closed, check for water or contamination in the tank |
| Bubbles at the gun, sputtering | Air entering through a damaged valve, seal or fitting; low tank | Inspect and replace the part; keep the tank topped up |
| Smooth on metal, bubbly on the board | Moisture in the board | Store board dry and at room temperature; check the board lot |
Running PUR?
PUR cures with moisture, so moisture in a PUR system can start a cure in the tank, hoses or nozzle. Keep the tank lid closed against humidity and keep packs sealed until loading. See how to purge PUR hot melt and PUR edgebanding and profile wrapping problems.
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Related
How to solve hot melt application problems · Hot melt application trouble-shooting tips · Hot melt system trouble-shooting tips · Hot melt adhesive · Stringing · Pop-opens · Charring and gelling
Hot melt bubbles FAQ
How do I tell if the board is causing bubbles?
Shoot a bead onto a clean, dry metal surface. If it is smooth on metal and bubbly on the board, moisture in the board is the likely cause.
Can wet hot melt pellets cause bubbles?
Yes. Store hot melt sealed and dry, and keep the tank lid closed so moisture and dirt stay out.
Do bubbles weaken the bond?
They can. Bubbles reduce the contact area of the bead and can leave weak spots. Fix the source rather than adding more glue.
