Name: Michael

Message: Would you have any information on potential hue shifts of Lanaset dyes due to fading?  I'm interested if Lanaset Blue 5G and Lanaset Green B undergo any hue shifts as they fade.

No, I'm sorry, I don't. It's an interesting question, but not one I have any information on. I have numerical data on lightfastness for many dyes on my page "Lightfastness of Different Types of Dyes", but no notes on changes in hue.

Usually, dyes keep the same hue when they fade, only becoming lighter, as the energy from the light destroys the colorful part of the dye molecule, but this is not necessarily the case for every dye. Occasionally a light-damaged breakdown product of the dye may itself have some color of its own, with a different hue than the original undamaged dye.

Lanaset dyes are more lightfast than many of the alternatives. This is particularly true if you compare them to the French dyes (Pebeo, Sennelier Tinfix, Dupont, etc.), some of which are notably poor in their resistance to light fading. 

Linda Knutson, in her book Synthetic Dyes for Natural Fibers, gives a value of 5 to 6, out of 8, for the lightfastness of Lanaset Blue 5G on wool, but does not supply a figure for Lanaset Green B. 

You may be able to get information on the lightfastness of your dyes if you contact your supplier. Huntsman, the manufacturer of Lanaset dyes, provides documentation about their dyes online, but only to their customers. Dye manufacturers almost never deal in small quantities such as hand dyers purchase, so the retailer you get your dyes from should request it from them for you, if they do not already have it.