Lustres are metallic colourants in colloidal suspension. They
provide intense reflective colour. They are most effective when used sparingly
as accents. They are supplied as a dark brown viscous liquid in small bottles.
They are widely available from ceramics suppliers.
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| A bar with gold lustre. Credit: Bath Potters |
The application of these is important, and not only because
they are expensive.
They must be applied to clean dry surfaces with a smooth
brush. The gold, platinum, copper, and bronze lustres do not need dilution. The
brush should not have a lot of lustre, nor too little. Too much causes burning,
flaking, dullness or clouding during and after the firing. The application must
be uniform in thickness. “Application
of lustres is possibly the most important factor in achieving the best results.
The more richly coloured lustres require a fairly thin coat while other lustres
(particularly the metallic lustres) require an even thinner coat.” Bath Potters.
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| silver lustre brushed on. Credit: Pottery Crafts |
The kiln should be vented until the carrier has burned off. The
absence of the smell will indicate when this has been achieved. The firing of lustres
can be between 586°C/1088°F and 733°C/1353°F. Metallic lustres usually fire
between 586°C/1088°F and 617°C/144°F. These lower ones are in the slumping
range of temperatures and can be applied to the flat blank before slumping or
to the completed flat blank depending on the requirements of the lustre.
