I picked up a 1920s, silver-plated cocktail shaker from the op-shop. It is super fabulous. However, the inside is all black. Is it safe to make and serve cocktails from this shaker? What should I use to clean it?? Thanks xx irene
Yes, it's safe.
Silver tarnishes easily, particularly in contact with sulfur-containing foods, particularly egg. The tarnish is not hazardous, and can be cleaned off with silver polish or with DIY chemistry like in Tetsujin's answer. Black tarnish doesn't form readily on its own, so if you're not planning on using eggs in your cocktails then cleaning off the existing tarnish will likely last you a while (it'll be bright silver initially, but will quickly tarnish to a dull greyish silver). However, it can also be ignored (which was apparently the approach taken by the previous owner).
Cheap & cheerful trick...
Break your shaker down into its separate components.
Use your washing-up bowl.
Get 30cm or so of aluminium kitchen foil, & get it to sit in the bottom of the bowl. Doesn't matter of you have to crinkle it but don't screw it into a ball.
Drop in your silver.
Add half a packet or so of bicarbonate of soda.
Fill with very hot water - from the kettle, ideally, just off the boil. Deeper than your shaker size Yup, it's going to be hot, be careful. Use gloves & a wooden spatula for manipulation. Give it a good stir.
Push it round for a couple of seconds with the spatula until it stops fizzing.
If it's particularly ornate, you might have to use a toothbrush, but you really shouldn't need to.
Remove clean shaker, discard now black foil.
Repeat if necessary.
It can smell a bit eggy & can taint the bowl, so if you've got a large 'glass' [pyrex etc] heat-resistant bowl that can stand boiling water [be very careful] that may be a better choice , but the washing up bowl can be bleached out if the smell lingers.