I recently dug a 2 gallon stoneware brown glazed jug stamped with the name J Fisher Lyons NY(1878-1902). It has heavy rust stains through out, what is the best way to remove rust from brown glazed stoneware jugs? I'm extremely cautious with this jug, as I couldn't believe it when I dug it out and it was whole. What is the best way to go about cleaning it ?