Can't get my flask clean?

textbook

I put biocabonate of soda and boiled water and vinegar for 24hrs but the black stain won't leave if it is a stain or thje metal inside has peeled off. Not sure. Has the flask had it? I left it stained since last winter

tonyh66

Bleach kitchen spray and hot water for an hour then use your mix

FreeBear

Denture cleaning tablets.

elsien

What have you had in it?

knightstyle

I used to clean glass flasks using a little sharp sand and a pinch of bicarb.
A good shake, leave to soak, shake again usually did the trick.

kazwookie

Bleach and water, for about an hour, then rinse well and rinse again

ohreally

Buy a new flask.

rach_k

Don't mix bicarb and vinegar. It fizzes which looks like magic but is actually them cancelling each other out (alkali plus acid). If you want to use them, use vinegar first (acid) then use bicarb afterwards to scrub.

I'd bleach it (Milton tablets are easy to use). If that doesn't help, maybe time to get a new one and take good care of it.

Mistral001

Flasks have to skins of glass. Are you sure that the stains are on the inside skin? If the are on the outside skin they will not be in contact with the contents of the flask and skin will not be relevant.

coffeehound

If it's a stainless steel one you could safely try dishwasher liquid or a piece of a tablet.

jk0

Recently, Thermos flasks I have bought have gone mouldy on the rubber seal fixed to the cap. I have solved this by carefully removing the seal before washing.


BTW, you can order new caps from Thermos, if anyone else has the same trouble.