Please can anyone advise me of what I need to buy to re-fresh white clothes that have gone off colour in the machine? My daughter has a white blouse with a black 'tank top' thingy attached. Do I need some kind of bleach that refreshed the white without damaging the black?
I think you're going to have a problem here. Black and white simply don't mix together in the wash, whether you do it in the machine or by hand. . Anything you do to try and refresh the white blouse will cause the black colour to fade and look horrible.
I think the only answer if to try and educate your daughter to think about the practicality of laundering clothes effectively when she's buying them. Anything which has red trimmings on it too, is a similar "No, No" in my book.
There is a product on the market that is supposed to remove the colour from items when damaged in the way you describe. It's from the same makers as Glo-white (you'll find it in the supermarket near the laundry products, softners etc). But whether it'll work effectively in your case I couldn't say. Also, Ace bleach might work. Test it on a )hidden part of the black tank top. Good luck : )
Any product intended to increase whiteness / keep items white / remove colour from stained clothing contains Bleach ... simple as that ... as already pointed out ... it is probably best to put it down to experience ...
Non Bio Liquid / Liqui tab Colour specific detergents for Colours
Bio powders or tablets for white & light coloured garments that are not wool, silk or any other natural fibre.