What can I use to clean residues on metal, pics attached.

[Butterfly44]

Canvassing ideas on what to use to clean residues on metal. Have attached pics of limescale build up on taps and brass window handle. None of my usual cleaning products are doing anything.

Viakal on the taps.

Following this thread, as ever since I moved into my (rented) house 5 years ago my draining board has looked like the tap on your last pic! Have no idea what the weird liquid type markings are but nothing gets it off!
I actually cleaned up one of DPs trophies this morning with toothpaste - thanks to good old google so may be worth a try?

Viakal and a gentle scouring pad/sponge.

Barkeepers friend sometimes works on marks, not limescale build up.

Vinegar

It might be worth trying some wd-40 or baby oil.

Scour to get the grime off.
Vikal to clean and shine the metal

Viakal seems popular ...I'll give that a try 🙂

White vinegar soak cotton balls in it and stick them round the taps or whatever has all that limescale on it and wrap plastic bag or cling film round it. Leave overnight (or a few hours...yours looks bad so I would leave it over night) should come off with a clean after that.

Brass does not react well to vinegar. Fine wire wool or toothbrush and soapy water.

Viakal or Kilrock on the taps to get rid of the limescale.

However I'd be careful with the window handle as it may not be brass and what you can see might be where the "brass" coating has come off.

You can scrape it off with a 2p coin - the coin is softer metal than chrome so won't scratch.