We use a mild bleach solution and then put them in the dishwasher on the top shelf, always works for us. REcently I saw on TV someone using Cola to get rid of stains.
The stuff previously referred to is citric acid - buy it from your local pharmacy to be sure it's culinary (food) grade - very cheap - we use it for our babies bottle steriliser. personally, would put all the cups into a bowl or sink, evenly spread a couple of tablespoons between each cup, boil a kettle & fill each cup to the brim & leave at least 30 mins, then empty, wash & sterilse with boiled water again xx
------------- Bringing up baby to be a seasoned caravanner - we bought one to holiday cheaply - working well so far - & caravanners are lovely - helped us on our virgin voyage & our awning!!!
all sounds good but involve a trip to buy something special, I always use simple Washing powder as one other camper has suggested but it works best with boiling water.
As spoonful of powder is enough in a cup, fill with boiling water and leave until cool.
I tried bleach - even neat! - on mine and it didn't work, so used Steradent tablets and they came up a treat. If you've already got Steradent tablets then you've nothing to lose by trying them first.
------------- Tigermouse
I have a very temperamental personality - 50% temper and 50% mental
Two slices of lemon in half a bowl of water overnight does the trick for me, i only found this out by drinking hot water with a slice of lemon in it as an alternative to gallons of tea i drink everyday,