Daler Rowney’s permanence ratings are compiled from testing in our laboratory and are given a one to four star rating:
The pigments used and how finely they are ground dictate the transparency of the Cryla Artists’ Acrylic colour. Pigments range from the most transparent, through semi-opaque to the most opaque. We use a clock face to further define the degree of opacity, ranging from 1 for the most transparent to 12 for the most opaque.
**** Permanent These colours possess the highest degree of fastness to light and are inert towards other pigments. These pigments have been proven and used over decades.
*** Normally Permanent In full strength these colours exhibit permanence comparable with the four star colours, but there may be some unavoidable loss of permanence if used in a thin glaze or much reduced with white. These are newer pigments.
** Moderately Permanent These colours either possess a lower degree of permanence than the previous class or they are not sufficiently inert towards other pigments.
* Fugitive These colours possess a lower degree of permanence than the previous class and are considered fugitive.