Richter began to use glass as a medium in 1967, when he made `4 Panes of Glass?, which were framed and attached to a stand that allowed them to swivel, and be looked through at various angles. Since then, he has made several mirrors, some plain and some coloured. All Richter?s works are to do with looking at reality - whether reproduced in paint, whether in the form of paint itself (abstract) or whether reflected or looked at through a frame - but his glass works have a cool, conceptual quality, that sets them apart. Richter?s `Corner Mirrors? have pigment attached to their backs, so that the reality reflected in them is coloured and, because mirrors reflect each other, their colour is optically mixed.