The books I've read all say to hold acid dyes at temperature (usually 185 degrees or so) for 45 minutes or so when immersion dyeing. I've found that with Lanaset/Sabraset dyes, the dye usually strikes within a few minutes of reaching 185 degrees, and at that point, the water is clear. The rinse water is clear as well. Do I still need to keep the temperature at 185 for 45 minutes, and if so why? Does it make the yarn more lightfast/washfast? I have never noticed running with Sabraset dyes, even when I pull it from the dyebath "early".
Been wondering about this for several years now, would love to know what is really going on during the lengthy dyeing period.