*** : Very good light-fastness = I ASTM Lightfastness ** : Good light-fastness = II ASTM Lightfastness * : Average light-fastness = III ASTM Lightfastness
Originally In developed in 1949 by Sennelier for Pablo PICASSO who had been looking for a medium that could be used freely on a variety of surfaces without fading or cracking.
The pigments are ground with an inert, non-drying binding medium that does not oxidise and that has no effect upon either film stability or surface. This base is then mixed with a neutral pH wax.