I have got a super-king patchwork bedspread which is all cotton andwas rather expensive. Being thoroughly bored with the colour I tried to dye it with machine dye in the washing machine which must have been too small, as it has only dyed in parts. It doesn't look good. 
If I tried hand dye, would it:
a) be colour fast afterwards?
b) turn my plastic bath blue?
I would probably have to soak it in dyegon first.
Any ideas?