New curtains - says to wash before use - why is this?

[Concepta]

Just bought some new curtains for my DDs bedroom - it says to wash before use - why is this? does it help them hang better or what? - I was just going to iron them and hang them up. Anyone any suggestions.

Thanks I will do that then. I know there was probably a reason.

I have recently bought new curtains. Is it advisable to wash them before hanging?