Wet glazing is the installation of glass in a frame where the seal between the glass and the rebate is a paste-like material — putty or sealant — that hardens after application. It is the counterpart of dry glazing, where preformed rubber gaskets provide the seal.
Build-up of a wet-glazed unit
- Rebate — the recess in the frame that receives the pane, with adequate edge cover and rebate width
- Setting and location blocks — plastic or hardwood blocks that carry the pane and hold it clear of the rebate base
- Seal — a bead of sealant or putty on the outer and/or inner face, pressed home and tooled smooth
- Glazing bead — in timber and aluminium frames the pane is secured on one side by a bead; the sealant closes the joint between glass and bead
Compared with dry glazing
Wet glazing accommodates any irregularity in the rebate; dry glazing requires dimensionally accurate profiles. On the other hand, a wet seal ages, dries out and eventually cracks, while a gasket is easier to replace. Replacing glass in a wet-glazed frame is more work: all the old putty or sealant has to come out first.
| Wet glazing (putty or sealant) | Accommodates any irregularity in the rebate; the seal ages, dries out and eventually cracks; replacing glass is more work because all old putty or sealant has to come out first |
|---|---|
| Dry glazing (preformed rubber gaskets) | Requires dimensionally accurate profiles; the gasket is easier to replace |
Applications
- Timber windows — traditionally with linseed oil putty, today usually with an elastic glazing sealant
- Restoration and listed buildings — with historic frames carrying thin glass or leaded lights, putty is the appropriate solution
- Single glazing in steel frames — with a suitable sealant or glazing compound
Points to watch
- Drainage and ventilation. The glazing rebate must be able to drain and ventilate to the outside. A fully sealed rebate traps water, causing timber decay and failed insulating glass units
- Blocks in the right place. Setting blocks at roughly a tenth of the pane width in from the corners, location blocks so the pane cannot bind; badly placed blocks cause glass breakage and sticking sashes
- Sealant choice. Use a sealant compatible with the glass, the substrate and the paint system; the wrong one attacks the edge seal of an insulating unit or cannot be overpainted
- Putty must be painted or it dries out and crumbles within a few years
- Do not mix systems. A wet seal on one face and a gasket on the other behaves unpredictably
- With insulating glass, compatibility with the edge seal governs; follow the glass supplier’s instructions
Related terms
- Dry glazing
- Glazing
- Rebate
- Glazing bead
- Putty
- Insulating glass
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