Inside Our High Wycombe Factory: How a Sealed Unit Is Made

Every unit that leaves our Marlborough Trading Estate factory goes through the same sequence. Here is the line, stage by stage, and why each step matters to how long the unit lasts in your frame.

Cutting and edge quality

Float glass arrives in jumbo sheets and is cut to size on a CNC table. Clean cutting matters more than it looks: edge micro-chips are where stress concentrates, so panes destined for toughening get their edges arrissed before heat treatment.

Washing

Every pane passes through a multi-brush washer with deionised water. Any residue left on the cavity faces would be sealed in permanently — the smears you sometimes see inside cheap units were baked in on day one.

Spacer and desiccant

Warm edge spacer is cut and bent to frame size, filled with desiccant, and bonded to the first pane with a continuous primary seal of polyisobutylene — the real moisture barrier in the unit.

Gas fill and secondary seal

The assembled unit is filled with argon, then the perimeter gets its structural secondary seal. Two different materials doing two different jobs: PIB stops vapour, the secondary seal carries the mechanical load.

Final checks and despatch

Units are checked for coating orientation, spacer stamp, size and visual quality, then racked for our own-van delivery runs. Curious about a spec for your own project? Details live in our technical resources, and the quote calculator prices any build-up in under a minute.