Try this
http://www.brownells.com/.aspx/pid=1...GLAS_reg__DYES
You could also use any of the woodworking dye powders sold on the wood working sites.
The question is how well any dye will work in Devcon as it is about 90% powdered metal. So it would seem that the predominant color is gray before you start trying to color it.
RWO
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