What is left in the pot?
Dyeing wool means knowing a bit about the properties of the dye. This won't be a complicated blog, just one that many have observed already. What is left in the dye pot after the dyeing and heating process is finished?
I chose a project that requires quite a few values of yellow. Yellow, to me, is the hardest color to get to come out perfectly. After the dyeing, citric acid addition, and heating is finished, the pot still has dye in it no matter what value I try. Well, do this the next time you dye yellow, or any other color that doesn't completely clear upon heating.
Make sure that there is adequate citric acid in the pot and that the time it has heated is sufficient. Remove the pot from the heat and place on a heat safe surface. Remove the lid from the pot to allow the steam to release. Take all precautions and use a face mask, eye protection, skin protection and heat proof gloves at all times when working with hot wool.
Let the wool sit in the hot water and cool gradually. Every 5 minutes stir the pot with a heat safe tool. Why do this? Well, if a piece of wool sits in dye in one place, the dye will settle onto the wool in a splotchy pattern. Unless a splotchy pattern is the intent, it is an otherwise bad outcome when trying to achieve a smooth gradation. Stir, stir, stir, until the pot is cool. Now look at the water. The wool fibers have soaked up the very last bit of dye in the water. The water is clear. The cool temperature has closed the follicle on the wool and trapped the color inside. Now when the wool is washed, rinsed and dried, dye won't come out.
Now, that is yellow, but it also happens to other colors especially colors with yellow in them like aqua, greens that contain yellow dye in their base formula, or blues that contain yellow. When dyeing these colors up watch the water in the exhausted dye bath. There is still color there after simmering and citric acid addition. Follow the same procedure to cool the wool slowly and stir, stir, stir. The blue will be a different result if it is pulled out of the bath hot. The yellow in the dye mixture won't have completely adhered to the wool core and a different color will result than if it is allowed to take up all of the dye particles upon cooling. This is particularly important if that specific color needs to be dyed up again. If it is allowed to cool completely then it is known that all of the dye particles it started with in the pot are in the wool. It takes away some of the difficult variables and makes a more standard process. Standardization is a good thing when dyeing for others as well.