Blue Wool Scale

Description

The Blue Scale, also called Blue Wool Scale, is used as a reference and for control in light fastness tests.

The Blue Scale can be used to document the effect of light irradiation, e.g. on paintings, prints and textiles. The control element consists of 8 blue textile strips which are glued on top of each other on a card, whereby the respective following strip is about twice as lightfast as the preceding one. For use, a part of the card (50% vertical) is covered during exposure and after the exposure phase the colour change of the exposed strip is compared with the unexposed strip. The Blue index (from 1-8) is a measure of light fastness.

The Blue Scale is supplied in a black envelope so that light-protected storage is guaranteed until the intended time of use.

Dimensions of the card: 130 x 45 mm (L x W)
Dimensions of textile strip: 8 x 45 mm (L x W)