A problem I occasionally have had in immersion dyeing is the darkening of small parts of the skeins. In the case of deep colors, parts of the skeins might appear almost blackened. This discoloration, strangely enough, didn't have any negative effect on the weaving. Still, it was an issue I wanted to solve.
STAINLESS STEEL POTS
The solution began when I thought about the pots I use. They are stainless steel. Aluminum would have an adverse effect on the colors. But they are cheap stainless steel pots. This means that the pots, including the bottoms, are very thin.
Also my stove is gas. The bottoms of the pots get very hot, and because they are so thin, the inside of the bottoms get very hot as well. And after the initial period of dipping the skeins in and out of the dye liquid, I pretty much didn't move the skeins at all. For two hours. The parts of the skeins on the bottom actually burned! Just like food.
I had read once that using marbles would solve the problem. I am sure they would. But I had none and didn't really know where to buy them.
So, when it was time to dye these red silk yarns for the warp, I decided that I just had to stop being lazy and move those skeins about a bit every once in a while. The first hour (after than initial period of continually raising and lowering the skeins) is not hard because I have to stay very close to those dyepots. During that first hour I am trying very slowly to raise the temperature from 120 degrees to 180-190 degrees at the rate of 1 degree per minute. This requires constant checking and occasionally manipulation of the heat. So I added to that, occasional rearrangement of the skeins.
The second hour I am much freer to go do other things because by then I have a handle on where the burner has to be to maintain the 180-190 degrees. So I set the timer for 15 minutes and every 15 minutes I returned and (also checking the temperature) re-arranged the skeins.
The result, I am happy to say, is that there didn't seem to be any scorched parts on the skein.