The Colour Stability of Lovibond® Glass
The long-term belief, widely held by The Tintometer Ltd and industry alike, has been that the glass colour standards included in Lovibond®instruments and discs are colorimetrically permanent (excluding physical changes due to contamination by dust, sample spillage etc).
To endorse the accuracy of this view, The Tintometer Ltd has conducted an accelerated test, a technique used in the photographic industry, to compress the time scale of any natural fading. The test involved monitoring the effect, over time, of controlled exposure to a high intensity light source on a set of Lovibond® glasses.
Examination of test results showed that any measurable change in chromaticity of the Lovibond® glasses, due to exposure to high intensity light, is small enough to be accounted for by instrumental tolerance as opposed to glass fading. This conclusion is supported by the lack of colour change detected by trained glass graders when comparing the irradiated glasses with the master standards at The Tintometer Ltd.
The glass, which makes up our colour standards and water test discs, can be described as effectively ‘permanent’ in colour.
A series of internal tests on Lovibond® glasses, designed to verify this statement, have shown that when exposed to a very high intensity light source of 135,600 lux for periods of time of up to 100 hours, the changes in colour that take place are within the tolerance of instrumental measurements. Moreover, visual examination of irradiated glasses by trained glass graders confirms that no glass fading is evident.