This has been posted as a comment, but I wondered if some of you may have missed it and are also confused about what I mean by dye stock solutions, so I'm putting it here as well.

When I dye with acid dyes I make the dyes into solutions. That is, I use 5g of dye powder and dilute with water to 500ml. This is my stock solution and will keep indefinitely in a bottle in a cool place. When I want to dye fibres or yarn, I weigh the dry fibres and for each 10g of fibre I use 30 ml of dye, 10ml of vinegar and 10ml Glauber salt solution if I am immersion dyeing. That is if I want the full depth of colour. If I want paler tones, I decrease the amount of dye to, say, 10ml. For this sort of random dyeing, I soak the fibres in a vinegar and water bath before dyeing and omit the Glauber salts.For example, if I was dyeing 30g of fibre, I would weigh it dry, then put it to wet out thoroughly. When it is wetted out, I would prepare my dyes - say red, yellow and blue. If I wanted equal quantities of each colour, I would use 30ml of red, 30ml of yellow, and 30ml of blue. This should give me enough dye to cover my fibre adequately, and not waste much. If I wanted to do pale red, pale yellow and pale blue, I would use 10ml red stock solution diluted with 20ml of water to give me the right amount of liquid but the paler tone; 10ml blue stock diluted with 20ml water, and 10ml yellow diluted with 20ml water.Sorry if this is a bit compliacated, but do ask if any of this is not clear

Jane