Wednesday, July 30, 2014

There's always something...

pH matters.  Really.  Ask me how I know.

On Sunday, I did another round of indigo dyeing--mainly, redyeing of some solids and itajime FQs in order to try and build up more color, but also a few new pieces.  The stock solution looked good, and I thought I had a strong vat, but late in the day, it seemed to me that I wasn't getting nearly as dark a blue as I expected after six rounds of dipping.

I wasn't very rigorous about checking the pH.  I was reusing the stored solution from my last vat, and usually the problem is the extremely high (alkaline) pH that comes from continually adding in new stock solution.  Although the vat does get more acidic over time, due to chemical interaction with the air (specifically, the carbon dioxide, according to J. N. Liles), I figured that wasn't happening quickly enough to counter the new stock solution, and I didn't want too alkaline and corrosive a dye vat.

I did check the pH of the vat before adding new stock solution, and it was at pH 9--on the weak side for dyeing cotton, but significantly alkaline.  I therefore made the stock solution with less lye than usual and assumed it was enough, but didn't recheck the pH.  After three dips, the level of the dye solution in the vat was too low, so I added about 1-1/2 gallons of hot water, in addition to more stock solution.  Three dips after that, I noticed that I wasn't building much more color.  I checked the pH, and it was only pH 8!

Not good at all!  I mixed three tsp. of lye in water and added it to the bath, which got the pH up to 10.  After that, the final two rounds of dyeing for the day yielded much better results.

Every time I start to think I know what I'm doing, something else pops up.  I will just have to keep playing indigo whack-a-mole, but one of these days I will manage two unproblematic vats in a row.

Even so, although the final colors won't be as dark as I had hoped, I had a good day at the dye vat.  I'll do a full show and tell after everything is washed and ironed, but for now, here are a few scenes from the morning after:

Linking up to WIP Wednesday on The Needle and Thread Network.  Happy sewing, everyone!


  1. This sounds very complicated! Your fabric is very beautiful in spite of ph wowes.

    1. Thank you! Someday the dyeing will be much simpler, once I get it right!

  2. They look fabulous! Looking forward to seeing these fabrics made into quilts someday.

  3. That leafy design looks good, and the crisp lines on the diagonal one are amazing! One step back, two steps forward!

  4. thanks for sharing! I've got all the supplies, but still haven't been brave enough to put everything to work. I really need to carve out a day and get that done. I do love reading about what is working (or not) for others.