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I pulled a favour with one of my work mates and he did some elemental analysis of gold dust brushes. Couldnt see any gold?? If it was there it was below the detection limit of the instrument. In fact we were hard pressed seeing any copper as well!! The brush was essentially carbon with silicon. Either the silicon was added in or was part of the binder (glue).

Interesting stuff. So is golddust a trade mark name rather than a description of the content of the product?

cheers
dr fabio

When I was still working I had some tires and bearings analyzed by EDS (energy dispersive spectrometry). That is a good technique to use for this sort of thing. I was able to determine that Ortmanns were urethane rather than ordinary rubber or some other elastomer. A lot of the better quality HO motor brushes are 80% copper. Silver is the best conductor, but it is only 5% better than copper. Gold is 71% as conductive as copper, so it would not make much sense to make motor brushes with gold. I do not believe that I have seen any motor brushes that were pure carbon, carbon is not a good conductor and I expect that the silicon was there as an impurity since it is a very common element.

They can call them whatever they want. I go with what works best, and that is
Gold Dust, followed by Big Foots.