Originally Posted by Eldi
Do you have any suggestions for pink-to-green ratio, at least for a starting point?
I honestly didn't record my measurements when I did it. I just eyeballed it using a chart. I have one of these that I refer to when I need to mix, mute, and darken/lighten dye colors:
Also, because this sweater looks fairly pale, you may also need to use less dye quantity than normal or pull it out of the dyebath early so the color comes out less intense. I think you need to mute the dye color AND reduce the "take" a little.
Also, if I found a yarn or garment with the same fiber content, would I be able to accurately test my dye mixture on it?
Yeah, you should be able to get a pretty good estimate if you can match the base color and the fiber content.
For best accuracy, use measuring cups to keep track of dye proportion and a scale to measure quantity of material.
One warning: as dyeing tends to involve heat, this WILL shrink whatever you dye. The amount of shrink depends on fiber and temperature (and it may have something to do also with the rate at which temperature is applied). You will need to take care with a knitted sweater.
I've dyed long socks before and I noticed that they were a little more snug after dyeing; they ended a few inches lower than they did pre-dye. The content of those socks was cotton/acrylic/spandex, and they were dyed with a fiber reactive dye which, as far as I understand, uses a lower temperature than iDye/iDye Poly. (I've never used anything from the iDye line so I can't give you first-hand anecdotes about that stuff specifically.)
For this reason, it's generally better to dye raw materials rather than finished garments whenever possible.