Encapsulating Glass

Points to note when making panels for encapsulating leaded panels in double glazing units.

In building a new panel, the perimeter should be of “Y” came. This allows the double glazing spacers to be placed on either side of the leg of the “Y”, incorporating it into the structure of the whole unit.

The tolerances for double glazed units are much less than for single glazed wooden units.

If you decide to use mastic, it must not be linseed oil cement, as the oxidisation process produces a condensate that fogs up the interior. Use a butyl putty instead.

It is also possible to finish the panel without any mastic under the leads, as the double glazed unit will provide the structural support. You do need to dress all the flanges of the lead to the glass to avoid light showing around the edges of the glass.

Finishing the leads should be with a polishing brush only to avoid introducing chemicals in a closed atmosphere. The polishing brush will bring up a dark colour on the leads and solder joints with repeated light brushing. This also is an indication that the solder jointing should be as neat as possible with small flat joints.