Convex Shapes for Wall Hangings

The most common shapes for wall hangings seem to be the “S” or wave form in various sizes, and flat pieces of what ever outline supported by stand-offs.

There is another possibility.  You can produce a shallow domed shape which can work well for either landscapes or abstract pieces.  They will be best if circular, although rectangular forms can be used.

The usual resistance to doing this is that the surface will be marked, or that the tack fused surface will be flattened.

There is a way to do this without either effect.  Place the work upside down on a mould of appropriate diameter or dimensions and fire the piece slowly to a low temperature. 

Raise the temperature more slowly than you usually would for a slump in the normal way – top side up.  This allows both surfaces of the glass to be at the same temperature at the same time.  This equalisation of heat throughout the piece will protect against any breaks or splits on the underside of the glass – which will become the top surface.

Set the temperature for about 620C, depending on the span of the piece.  This temperature will be suitable for pieces of 300mm to 400mm and 6mm to 9mm thick.  Pieces with a smaller span will require higher temperatures or longer soaks.  Larger pieces will need a lower temperature.

You should set the soak at about 45 minutes. You will need to observe at intervals until you have the amount of depression you wish.  You will also need to know how to advance to the next segment of the schedule when that point is reached, so that you do not over slump the piece.

Since the piece only touches the mould at the rim, and you are not allowing much movement in the glass, you will not mark the glass with the mould. 

This process of making a domed wall piece will be unusual, although it will not be appropriate in all circumstances.

More detailed information is available in the e-book: Low Temperature Kilnforming.