Making curtains - do I need special lining fabric?

[DitaVonCheese]

This isn't very exciting but I need to make some curtains for our spare room. Do I need to buy special lining fabric or can I use anything I have lying about? I have a couple of old sheets I thought would probably do the trick.

I can claw back my A&C credentials by saying I made a pair of trousers for DD out of an old jumper last night (and they fit! ) and um half a door stop

Thanks, have done some googling also in the meantime and sounds as though sheets will be fine. We have blackout stuff in bedrooms we use all the time but in the spare room I'm not so bothered

I suspect that I will um never wash them