These are resin plates ( on a thin metal bed )
which harden when exposed to Ultraviolet light.
To make the image, one can use a photographic
negative or a template made with opaque black
on transparent film. This is then clamped to the
plate, and exposed to the sun or put in an
 Ultraviolet light box.  After exposure the areas
of protected resin can be washed away, leaving
 quite deep pits and lines. The plate can then be
printed like an etched metal plate. 
To learn about Solar printing, contact Kew Studio via Sally.

Autumn Garden
price £55 from sallyhunkin@kew-artists.com