Canner rack turned black

I canned 10 quarts of tart cherries this year and my rack for the waterbath canner turned black! It didn't get that much lighter in color when I washed it with warm soapy water when I did the canner also.
Anyone know how to get the color turned back from black?
Will the black color ruin anything else I can using it like that?
I want to make some apple pie jam now that apples are coming in season but don't want to waste the time and effort ( not to mention the ingredients) if this will some how ruin the batch.
Thanks in advance