Fine Art Trade Guild Standards for Limited Edition Prints.

The purpose of the Guild Print Standards is to protect the interests of consumers and maintain confidence in the art and framing industry. Artists, publishers and fine art printers are encouraged to promote their high production standards and the integrity of their limited editions.

Key requirements

• Lightfastness of finished print – results of 6 or more on the Blue Wool Scale in all areas of the print – or its equivalent under empirical test conditions.
• Guild standard pH for substrate of 7-9, amended September 2002 to pH 7-10
• Minimum weight of substrate of 250gsm.

Testing Standards
Standards for blue wool testing are defined by:
ASTM D5383-97
Standard Practice for Visual Determination of the Lightfastness of Art Materials by Art Technologists
Results Blue Wool 6 = 100 years display life

Blue Wool Scale
Measures and calibrates the permanence of prints. Two identical test prints are created. A calibrated blue wool test strip is masked (1/2). The strip and one test print are placed under xenon lamps in accordance with the test standards. The other print is stored in the dark as a control. At various times, the test print is compared to the control print. When visible fading is evident the wool test strip is examined. The amount of fading is then measured by comparison to the original color and a rating between 0 and 8 is awarded. Zero denotes extremely poor colour fastness while an Eight rating is deemed not to have altered from the original and thus credited as being lightfast and permanent.

Blue Wool 6 is the accepted standard for limited edition prints.