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How to use PUR hot melt for vinyl-wrapped uPVC glazing beads
Glazing beads are small, they get handled hard, and they live outdoors. That makes the glue line the weak point on a wrapped bead. Reactive hot melt (PUR) is the standard answer. Here is how to set it up, and what to check when the foil starts lifting. Call 800-249-0337 for an SDS and a sample.
Why PUR for glazing beads
A wrapped glazing bead sees sun, heat build-up on dark foils, freeze-thaw, rain and cleaning chemicals for decades. It also gets snapped into the sash, which flexes the bead and stresses the foil edge.
A conventional hot melt is thermoplastic. It softens again when it gets hot. On a dark foil in summer sun, that is how edges creep and lift.
PUR sets as it cools, so the foil holds as soon as it leaves the wrapping rollers. It then crosslinks with moisture into a thermoset that does not remelt. That second cure gives the heat, creep and moisture resistance a window part needs. Cattie PUR bonds hold from about −40°F to +300°F once fully cured.
What's in this guide
- What you are bonding
- Surface prep for uPVC
- Primer: where it goes and why
- Running the line
- Cure on non-porous parts
- Common adhesion failures on glazing beads
- Troubleshooting checklist
- Which Cattie PUR
- Related guides