Hi Sam, This did not remove the marks unfortunately. Have you got an email I can send you pics to. All the best Rick 'Hi Richard, I am so sorry to hear the issue with your flask! What the marks might be is residue from a type of polish we use. All our pewter items are handmade and in the finishing processed they are polished with a really thick and heavy polish, this is what makes the pewter so shiny. Very occasionally some of the polish is missed and it can form dark marks on the pewter and can look like scratches or discolouring of the metal. Can you try giving it a wash in warm soapy water? If it is polish it is easily removed. Can you try doing that and let me know how you get on? ~ Sam'