What is the BEST way to clean heavy tarnish off old silver?

Put strips of aluminum foil in a large bowl. Place silver on top. Cover the silver will boiling water and add 3 tablespoons of baking soda.

Use a good quality silver polish and a soft cloth, turning it frequently to avoid redistributing tarnish. If the tarnish is heavy, it may take awhile.

There are products that are supposed to be faster or easier, but most of them can damage the silver with regular use. I won't use them on my heirloom service.

Try using baking soda to take it out