Thanks to all for your suggestions. I thought you might like to know what worked for me. I tried the clorox & peroxide leaving them on for a few hrs. – neither worked. I made a paste of the cream of tartar w/water & left it on overnight – this morning all of the stain is gone except one tiny spot. Hopefully it’ll be gone when I reapply tonight in the same area. Just thought you might want to know the result.