This is what we're dealing with:
There are five colors in this piece: ochre (outlines and shading), gold (the metallic parts of the crest), turquoise (blue parts--the actual crest's "night" color is more turquoise than blue), orange (lightning bolt) and black (Berlin bear). Only the turquoise and gold needed any work--the rest of the piece hadn't faded at all.
The piece went awry in a strange way: little spots in the turquoise and orange areas got lighter over the year I've had it. It doesn't look like sun damage, especially since the tattoo is in a place that doesn't get a lot of sun anyway. Right now I've got a polo shirt on, and you can't see the tattoo. If I wear a tee-shirt, you can see part of it, and the part you can see didn't fade.
Here's a fun article:
http://www.bmezine.com/news/edit/A30205/arttatto.htmlApparently the way this works, when you receive a tattoo your body assumes it's a foreign object that has to be removed. If there's any of it left after a couple of months, your body assumes it's a foreign object that can't be removed and builds a wall around it. (Which is why the artist goes over the area several times--he's trying to build up an unremovable foreign object in there.) If part of the tattoo is in an area that is well-served by your immune system (which carries ink particles to your lymph system--anyone who has tattoos has ink in his or her lymph nodes), or the tattoo is in a color that your immune system can process easily, more color will be pulled out of the tattoo.
The article also says why sun fades them: sun breaks down skin cells, and if there's a tattoo in the ones that get broken down...oh well!