Calibration of Littleton measuring instruments using test specimens of reference glass

Abstract

The determination of the softening point of glass according to Littleton (Littleton point) is carried out by a conventional method of measurement. The measuring device and the method of measurement are standardized. The calibration of Littleton measuring instruments is performed with the aid of test specimens manufactured in the laboratories of the glass industry from standard glass with a known Littleton point using various technologies. Owing to the availability of test specimens which are machine-made and traced back to a standard measuring device and whose Littleton point is certified, deficiencies of the usual calibration procedure are avoided and the comparability of the measurement results is improved.