Black Anodised Parts Now Turning (or Turned) Slightly Crimson/Reddish

We have some black anodised parts that are either slowly turning or have already turned a crimson colour.. the black has a tinge of red in it....

is there any possible reason... base metal is 6082-t6.

Thanks,

First of two simultaneous responses -- September 26, 2008

1. Probably not sealed. do a seal test.

2. Lightfastness of the particular black dye.

3. Iron embedded by shot or sand blasting or tumbling in media that has been use on iron. Embedded iron when "oxidized" is reddish.

Second of two simultaneous responses --

It sounds like either the dye is worn out and needs replacing or the dye is not light fast and is being faded by the UV.