My 1DX is exhibiting some sort of white residue buildup on the top dial, but it stays clean on the ridges where I touch it the most.
Perhaps its the same thing that happened with the T4i's:
Phenomenon The front rubber grips of some EOS REBEL T4i units produced in certain lots between May 31st through June 27th, 2012 may turn white after a short period of time. We have determined after inquiry with the rubber manufacturer and analysis, that the white substance is zinc bis (N,N’-dimethyldithiocarbamate).
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