This week: stop bleeding yarns, find the perfect ph for your indigo vat and scouring/dyeing blends
Every week, we are emailed with questions from our natural dye community asking simple and complex questions that we thought might be worth sharing. Of course, all of your burning questions are answered by natural dyer in chief, Kathy Hattori, Founder of Botanical Colors.
What do you do when you buy hand dyed fabric or skein of yarn that keeps bleeding color? I have a friend who bought a couple of skeins of yarn, one cotton, one wool/silk mix and she was going to rinse/dry them before she started to weave with them as they have been bleeding color for five weeks now. She washes, rinses, dries and they bleed each and every day. She is not going to weave with them any longer due to the color bleed. But, it has now become a challenge for her. The density of the color has not changed much at all. It is quite odd!
If a yarn or fabric has not been dyed properly, it will crock, or rub off or heavily tint wash water for many, many rinses and possibly never stop bleeding. A small amount of tinted rinse water is okay for the first couple of casual rinses, but if the goods continue to heavily color rinse water, the piece hasn’t been dyed well. A possible culprit may be inadequate scour and mordant processes. Properly preparing yarn for dyeing is important for successfully dyed yarns, especially those that will be subject to abrasion or pressure, like in weaving and knitting.
What happens when the pH of the vat is too high, let’s say well above 12? What are the consequences? Does it crock? Does it strip the color away?
A super high pH above 11 can potentially damage protein fibers, making them look dull and cottony and feel brittle. I don’t know if it contributes to crocking, or excessive rub off or stripping but the recommended pH for cellulose is between 10.5 and 11. If your vat pH is too high, lower it with a small amount of a mild acid, such as vinegar.
I am looking at some silk cotton voile 60% silk 40% cotton I’d like to use and dye. I’ve never dyed a blend before and wondering if it’s possible? Would I follow the same scouring instructions as silk? The dyes I’d like to use would be madder, onion skin and cutch (maybe indigo).
Normally what I do is look at the percentages of fibers and when it’s a cellulose/protein blend, I usually mordant and dye to accommodate the cellulose blend. The reason for this is that the mordant for cellulose that I most often use, which is aluminum acetate, can also be used on silk, and sometimes on wool fibers.
The scour should be fairly light (meaning a very low percentage of soda ash as to not damage the silk) as blends are typically well cleaned so that the fibers blend smoothly and I don’t worry so much about residual impurities on the fibers.
I hope this helps. Don’t forget the wheat bran post bath as this really helps brighten the shades.
Top image courtesy of Tolt Yarn & Wool