Sealed units are manufactured using two panes of glass of the same or different thickness. The most common glass used is 4mm float, which is not a safety glass, this is sometimes backed with an obscure glass. Where safety glass is required, the units will be made from toughened annealed or laminated glass.

The two panes of glass are washed so as to have all the dirt and grease removed. They then have an aluminium spacer bar set between them. This bar generally has the two longest lengths filled with desiccant, which absorbs any moisture within the unit. There are also small holes in the spacer bar, which allow the desiccant to breath. The spacer bar has a primary butyl seal added to both sides of it. The unit is then placed into a press to make sure the primary seal is intact.

Once the unit has been pressed it is visually inspected and the secondary seal is then applied. The unit is then cleaned and ready for delivery.

Spacer bar    Back to top

Light but strong aluminium bar available in silver, white, bronze, gold & black and in widths ranging from 6mm to 20mm in 2mm steps. The spacer bar is folded to shape and back welded by laser so no join is visible along the centre of the bar. Holes are punched along either side of the weld, which allows the desiccant to breath. The bar is then either bent or cut to fit the unit.


Desiccant    Back to top

Called a molecular sieve, the desiccant is highly porous crystalline aluminosilcates in beaded form.


Butyl (primary seal)    Back to top

This is a solvent free, non fogging, one component adhesive, based on polyisobutylene (PIB).


Secondary seal    Back to top

This is a two part polysulphide polymer filler, cured with manganese dioxide. This can also be a silicon sealant when required.


Sealed unit diagram    Back to top