Glass Bead Frame Heater
 Catalogue Number: 4263 Glass Bead Frame Heater Category: Equipment Sub-Category: Frame heater Corporation: British Optical Co Pty Ltd Time Period: 1940 to 1999 Place Of Publication/Manufacture: Sydney, Australia Publisher/Manufacturer: British Optical Co Pty Ltd Description Of Item: Grey hammer-tone steel box 215 mm x 167 mm x 175 mm standing on four black rubber feet with steel lined recess 175 mm x 127 mm x 65 mm. Front face has a blue on silver plate imprinted 'BRITISH OPTICAL CO. PTY. LTD. SYDNEY, 240V ------50C, Serial No. 7.5.2/110 Watt', a black knob diameter 45 mm imprinted 'OFF, ON, 1,2,3,4, FULL' and a red pilot light with chromed surround. The rear face has two multi-holed vents 30 mm diameter and a power cord attached. The underside has 'Property of Dispensing Course hand-written in black. Historical Significance: Frame heaters of this type were common in optometry practices for heating shell frames for fitting lenses and adjustments in fitting frames to patients. The recess was half-filled with fine (0.5 mm diameter) glass beads heated by an electric element in the lower section of the device. The frame or appropriate section of the frame was submerged in the beads to make the shell flexible. The unit was usually switched on at the start of the day at a temperature setting hot enough to allow frame adjustments without causing pitting of the surface of the material. When fitting lenses to a frame, care had to be taken to ensure all beads were removed from the bevel groove of the frame. Some practitioners substituted salt instead of glass beads. This was dissolved when the frame was cooled in a water bath after fitting. How Acquired: Donated by ACO Dispensary via David Leeming Condition: Fair Location: Archive room. East wall Unit 3 Cupboard |