Polly Gibson looks into the types of glass used to enliven London’s front doors.
You learn something new everyday; well I do at any rate. Today I’ve learned that glass is neither a ‘solid’ nor a ‘liquid’ – technically it’s apparently somewhere between the two and is classed as an ‘amorphous solid’. And it seems that the famous old urban myth about very old pieces of glass gradually becoming thicker at the bottom over the years is completely wrong! Window glass doesn’t flow downwards due to gravity. Differences in thicknesses in old panes of glass are due to the way they were made, not to the passage of time.
Front doors, and the fanlights above them, have long been used to admit light into what would otherwise be quite dark entrance hallways. Georgian, Victorian and Edwardian front doors between them show all manner of variations in the use of decorative glass panels. Leaded lights and stained glass were discussed in an earlier Bespoke Front Door blog – ‘Pieces of Light’ – so today I will concentrate on etched glass and cut glass. Grinding, cutting and polishing are about the oldest techniques used to decorate glass. It was to these our ancestors turned in preference to using large areas of plain obscured glass, a look which has more appeal to 21st century eyes.
Patterns were applied to initially clear glass by using either acidic or abrasive processes. Sand-blasting creates a frosted look by making tiny scratches in the surface of the glass. If part of the surface is protected by a vinyl stencil or by inking-on a design before the sand (or acid) arrives then, when the ink is wiped away or the vinyl peeled back, a permanent pattern remains, formed from alternating clear and etched areas. For a fully obscured panel it is necessary to first sand-blast the entire background and then to etch a decorative patterns onto this using acid.
Brilliant cutting of glass is a specialised and highly skilled craft. A design is drawn onto the surface and the pane is then maneuvered by hand against a profiled cutting wheel so that grooves are cut into its surface, carefully following the lines of the pattern. Traditionally, the glass was then obscured by hand, using a fine grinding paste. The brilliant cuts, being safely below the flat surface, remained beautifully bright and polished. Great examples of this craft still survive in period front doors across many parts of London.