"Brass, copper and pewter will shine if cleaned with the following mixture. Dissolve 1 teaspoon of salt in 1 cup of distilled vinegar."
Does this mixture also shine zinc?
And what about adding a cup of apple cider vinegar to the distiller and boiling for a few minutes with the lid off? I usually soak in a mixture of vinegar and water, but perhaps boiling would prove more effective...?