Can anyone help me or advise?
I have a lovely pale blue shirt from COS, purchased early this year. It is 75% cotton/20%polydamide/5%elastane.
Worn once then half way through day wanted to freshen it up and iron it - did so on low setting and a lot of inky dark blue stains have appeared as if by magic all over the shirt. It seemed to get worse when iron was touching edges of ironing board, as if a 'releif' was coming through - except my iron is pristine, clean and my board is white 
I imagine this can only have come from 'within' the fabric of the shirt itself.
I check instructions, just says you can iron it, no specifics.
I tested on another blue oxford shirt and few white tees, no issues whatsoever with my iron or ironing board.
Would you take it back to store and ask their advice?
It cost me a lot of money and I adore it.
So pissed off 