Because the effect only works with clean, unvarnished copper and alloys. As natural tarnish builds up and creates a surface, that effect goes away. and if you varnish or seal it to prevent tarnish, the effect doesn’t work. Plus, the same reactions that are why it self sanitizes WILL occur with lots of foods and equipment in contact with the counter. Do YOU want your philly cheesesteak to taste like pennies?
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