I have just noticed that the stainless flask I carry on bike trips has developed a comprehensive dark brown coating inside(I usually carry white coffee) and I have not been able to remove this. Has anyone any advice on what can be safely used to clean the flask?

Thanks

Milton?

Try some limescale tablets, that worked for me

Sand. No really, lob some sand it and give it a shake, it’s like a soft mini sandblasting session!

Bicarbonate of soda? Vigorous scrub with Camelbak brush?

Three or four teaspoons of bicarbonate of soda and boiling water and leave overnight.

Thanks – I’m trying the bicarb as I write.

My work mug was a bit tarnished and then one day when I was ill I had a lemsip (tesco own brand if that matters) and it came up pristine!

I drink black tea so mine gets very bad. A while ago I’d put soya milk in it and when I poured it out it was like chocolate Nesquick and my flask was like new. I still used the soya milk and lived.

try some steredent tablets

I think it might depend where you live- water hardness and all that…

Anyway, seldom happens to me here in soft water Sarf Sales. But I usually chuck a bit of sodium metabisulphite (homebrew sterilising solution)in to remove any lingering tastes.