The Blue Wool reference is used as a standard in the field of conservation to assess the lightfastness of works of art and other objects. The Blue Wool reference consists of textile samples that have been dyed with a specific blue color and exposed to light under controlled conditions. These samples represent different levels of photosensitivity.
The Blue Wool scale ranges from 1 to 8, with 1 being the most light-sensitive and 8 being the most light-resistant. Artwork and materials are placed side by side with the Blue Wool reference under exposure to artificial light. After a certain period, the color change on the artwork is compared to the change on the Blue Wool samples to assess how well the material withstands light exposure.
This system helps conservators and conservators make informed judgments about whether artworks and objects will be faded or damaged by light over time. It is an important part of the conservation process to preserve artistic and cultural treasures.