Tuesday, March 24, 2009

Red Cabbage Dyeing Lab Report #1

Environment

Pacific Northwest, close to sea level, city tap water known to be of fairly high quality

Yarn

100g KnitPicks Bare superwash fingering weight yarn (75% wool, 25%nylon) divided into three hanks (I wasn't impressed with how well the yarn itself emerged from the rigors of dyeing - seems a bit loosely spun)

Scouring and Mordant

Washed yarn in grapefruit-scented Ajax dishwashing liquid and rinsed. Simmered yarn one hour in 8% alum and 7% cooking cream of tartar. Rinsed, allowed to dry, and stored for a couple of weeks.

Dyebath Preparation

Chopped 250g red cabbage and simmered one hour (keeping temperature below 212 F). Let dyebath steep overnight - a lovely purple/magenta color, and strained out cabbage.

Dyeing

  • simmered yarn in dyebath one hour (keeping temperature below 212 - mostly gently bubbling) and achieved a pale, purplish gray
  • added 1/2 cup salt - no improvement
  • added 1/4 cup vinegar - no improvement
  • simmered another hour - no improvement
  • let sit in dye bath overnight - by now a bit more redness to it, but marginally so
  • during all this, the color of the dyebath remained essentially unchanged
  • rinsed yarn

Modifiers

  • swished one hank in ammonia water (4 glugs of ammonia from the half gallon bottle, as small as I could make them) until a nice pale green - a couple of minutes
  • swished another hank in ammonia water for a shorter period of time, so didn't turn quite as green (also not quite as even around the cotton ties)
  • swished the third hank in water with 3/8 cup vinegar - no discernible difference

Drying

Allowed yarn to air dry overnight, during which time all pretense at purple faded from the acid skein, leaving it gray with a few small bluish spots (like old mimeo). The greens also lost some of their joie de vivre.

All three colors look better in incandescent light than in natural light. In fact, oddly enough, the yellower light gives them a bit more redness.

Diagnosis

There are so many places I could have gone wrong - I don't have the experience to judge.
  • not enough alum
  • wrong cream of tartar
  • something in the water
  • dyebath too hot
  • not enough acid
  • wrong species of red cabbage
  • wrong season for red cabbage
  • process not as described due to unspecified user error
I do think we can rule out insufficient cabbage, given the beauty of the dyebath and the fact that it was not a whit exhausted. Also, while the nylon content probably made for a paler dye job, I doubt it changed the color.

Prognosis

If one wanted to knit a weathered 1930's gingham dishtowel, this yarn would be just the article. The colors are pleasant enough, but not really my style. Overdyeing is probably in the future. Maybe with blue, and something to sadden it a touch.

Given other people's experience of red cabbage finickity and its reputation for eventually greying in the best of circumstances, I doubt there will be a lab report #2.

Bibliography

Wild Color by Jenny Dean (sadly, out of print)
Natural Dyeing by Jackie Crook

2 comments:

Anonymous said...

Hi
While looking up cabbage dyes on yarn, found your site and wondered if the superwash wool is the problem.
Some are made that way with something that strips some of the wool scales that cause fleting and some are made that way by resin (?) coating.
Have some stuff in a pot ,so will check on them later. Also searching for greens, heard chrome in walnut , but dont know ok source of that (non-poisoness).
Keep up the fun

Lynn D

Lina said...

I still like your grey-blue yarn.

I've also made some dye experiments with red cabbage and iron liquor mordant. I've got blue fabric.

http://www.sewhistorically.com/how-to-dye-blue-with-red-cabbage-a-tutorial/