I have overdyed most of the yarn which had been dyed with plants. I started with Wilton food colouring gel on several skeins and mini-skeins and also bought a handful of acid dyes. I have to admit to being a bit disgruntled with 'natural' dyes, whereas acid dyes are reliable, versatile, easy to use in any quantity. I am knitting a pair of replacement gloves for my daughter (after collie-related destruction of original pair), so I split and dyed a 100 gr of Blue-face Leicester 4ply into 6 mini-skeins. As a skein of undyed Corriedale dk can be had for just over a fiver (from World of Wool ), I am going to have to be strict with myself.