Any tips? Its only about 5 weeks old, and gets washed out every day but tea stains have left it very brown inside and very dirty looking, not even 2 cycles in dishwasher have sorted it.
Just be careful what you do with it. I put boiling water in mine and shake it about. The other day the lid blew off and I got boiling water all over my face, badly burning me. Bloody flasks 
Get some of that stuff you use to clean/sterilise the water pipes in a Caravan, can’t remember the name of it now.
I use it one my flask (stainless) but it should work on any type & you don’t have to use hot water to do it.
Try Leisure sales up at Arclid if you’ve nowt closer.
HTH. 
Fill with warm water, one large spoon off bicarb, leave overnight, rinse, no stains, no smell. 
I put a couple of Steradent in mine with hot water leave for a while then rinse out. If you have Tea stains you may have to leave over night to soak. I do mine once a week and it stays nice and shinny no smells,also store with the lid of.
Good luck.
tea spoon of table salt and fill with boiling water leave to stand overnight then rinse well. like a new one in mornin 
M G b:
I put a couple of Steradent in mine with hot water leave for a while then rinse out. If you have Tea stains you may have to leave over night to soak. I do mine once a week and it stays nice and shinny no smells,also store with the lid of.
Good luck.
That is also the tip from my MRS so it MUST be the best one
hi bug i clean mine with soada crystals get them from any supermarket
i just put two table spoons in flask pour boiling water leave overnite
in morning rinse out nice and clean
ROG:
M G b:
I put a couple of Steradent in mine with hot water leave for a while then rinse out. If you have Tea stains you may have to leave over night to soak. I do mine once a week and it stays nice and shinny no smells,also store with the lid of.
Good luck.That is also the tip from my MRS so it MUST be the best one
Mine says it’s embarasing when going to buy then as the shop keepers think she got false teeth
Bug, once you got it clean, don’t make the tea direct into the flask, just put boiling water in there and make it as you need it, no more dirty looking flask and better tasting tea (insert hurling smilie here) works the same for coffee (insert more coffee drinking smilie here)
only fill it with water and carry a box of teabags and either sweeteners, sugar lumps or sugar sachets which are free in the services. I bought a box of those milk tubes for a fiver, they lasted me about 3 months.
You can always fill a flask anywhere, but to get tea, sugar and milk is more difficult
Oh and we got some stuff with a glass kettle called oast■■?
Just put some milton in it with hot water for a couple of hours.
Wheel Nut:
only fill it with water and carry a box of teabags and either sweeteners, sugar lumps or sugar sachets which are free in the services. I bought a box of those milk tubes for a fiver, they lasted me about 3 months.You can always fill a flask anywhere, but to get tea, sugar and milk is more difficult
I never thought of that… 
Rollo Tomasi:
Get some of that stuff you use to clean/sterilise the water pipes in a Caravan, can’t remember the name of it now.
I use it one my flask (stainless) but it should work on any type & you don’t have to use hot water to do it.
Try Leisure sales up at Arclid if you’ve nowt closer.
HTH.
Milton.
bicarbonate sode works a treat
Milton baby bottle cleaner Steradent or could try bleach in water solution
be careful rinse well
bleach it,
puta cup of bleach in it then fill with hot water. just remember to swill it before you use it or you will be drinking swimming pool water for a while.
then just put the hot water in it grab you tea bags, sugar sachets and milk and away you go!
old grizz:
bicarbonate sode works a treat
that’s what I use as well
dont bleach your flask as you erode the rubber and then you have a leakage problem. i know i wore my rubber out after six months and had to but a new flask