Spirals of fused silica have been extensively used in old thermobalances, because of the extremely low expansion coefficient of silica. Explanations or links towards how these objects were prepared are most welcome.
Idea is clear from this video http://www.youtube.com/watch?v=1vjRYv8EvDs
Such work can be done in glass workshop using thin rods made of fused quartz and spindle from glassy carbon ( with grooves for high quality). Glassy carbon have a low coefficient of thermal expansion, and does not stick to the glass.
However, industrial process is not far from prehistoric, but with more complex tools.
If you're looking glass with a really lower coefficient of thermal expansion then SiO2 (0.59×10−6/K) ,note to Zerodur (20 °C to 300 °C) : 0.05 × 10−6/K) and Ule glass (-0.03 to 0.03×10−6/K). Processing is also easier than for fused quartz.