SWEDISH BLUE:
Our local hardware shop sells the dye. Chuck the curtains in the wash machine,bung in the dye and job done
Depending on the material whether or not it’ll be very successful.
If material is faded unevenly then the new colour will not “even out” the colour difference unless it’s a very deep colour. It’s like putting a thin paint on an unevenly coloured undercoat: the base shows through.
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.copyright. MumsNet
And Martha Stewart site suggests bleaching fabric before dying. That’ll even out the fade, but will old material survive such treatment?