Cleaning glass decanter

[3catsandcounting]

This little decanter has been handed down over a few generations, but it has a cloudy, mottled build-up inside which I can't seem to get rid of.

The opening is obviously very narrow, compared to the wide bottom section, so a bendy brush won't reach round inside. I've tried sluicing it around with rice, and with warm soapy water, (as recommended by someone) but to no avail.

Any ideas?

You can buy special decanter brushes, I have one for a set of Edwardian decanters. They bend at the end of the mop bit - so they go in straight but can then bend once in.

I did have to trim mine though, as the neck is so narrow!

You can buy beads to swish round but if it’s delicate I’d use rice.

If you rinse in deionised water there’s no water marks.

I've got beads for doing mine and they work really well.

Is it limescale?. White vinegar over night would dissolve it.

Thank you everyone; some great ideas.
I'll try the white vinegar first, and I'll look out for some beads and little brushes online.

I think it could be Edwardian, Mary?
I guess it would have had a stopper too. No idea where that is.

If nothing gets it off it might have had a protective glaze that’s cracked and let moisture in.