Pewter items such as serving utensils and jewelry must be rust-free in order to be both attractive and useful. If you have old pewter that has not been stored in a dry environment, your pewter likely will have some rust formations. To remove the rust, you will need to clean your pewter thoroughly and carefully to insure that you do not damage the item while removing the stain.
Clean your pewter. If your pewter has been in storage for a long time, it may be difficult to tell what stains are simply an issue of age and lack of maintenance, and which ones are truly rust. Wipe down your pewter with a soft rag saturated with linseed oil and talcum powder to remove dark stains and render problem areas more visible. The oil and powder mixture can be removed using cotton swabs soaked in denatured alcohol.
Mix up a rust-removal cleanser that is safe for pewter. In a bowl, mix a tablespoon of salt, 1/2 cup of flour and a cup of vinegar. You will get a thin paste.
Polish the rust stains off the pewter using your cleaning solution. Dip a clean rag into the solution, then use gentle pressure and circular motions to remove the rust stains from the pewter. The salt will scrub the rust off but will not scratch the pewter. The vinegar helps loosen the rust.
Rinse off the pewter under warm, running water. Use a clean rag to help wipe the cleaning solution away as you rinse. Make sure that all traces of the paste are gone from the pewter before you move on.
Buff the pewter dry. Use a clean, dry cloth to dry the pewter. Pewter benefits from buffing anyway, so use firm pressure and circular motions to make it shine. This particular stain-removal tactic will leave the dark, protective patina of the pewter largely intact, which can help prevent the recurrence of rust stains.