what is the best condition for a commutator
a light straw
b jet black
c dull copper
d chocolate
i choose chocolate as we want to see a good commutator film graphite plus copper = brown

jet black was another possibility

dull copper would mean that there was no brush contact or it was new

light straw same as above

i have asked experienced electricains and motor builders who told me they would have picked jet black,dull copper and even shinny copper?

what do you think??

Frank;
i never really considered this finer point, it is very interesting...usually i am called when the 'smell' has differed