Cochineal on cotton, not simple

6 June 2015

All these cotton yarns have been dyed with cochineal.

All these cotton yarns have been dyed with cochineal.

Dyeing cochineal on cotton can be a challenge.  Cochineal on wool or silk is so easy.  It is all in the steps before the dyeing that determine the quality of the color ; scouring and mordanting.

Twenty years ago I dyed some cotton with cochineal and the samples are in the box, still dark and strong colors.  But then we did a scour, alum, tannin, alum mordanting—- that is four hot baths before you get to the dyeing. Today we generally use  two baths, a hot scour and a warm mordant and that is a big improvement.  Others have been working on mordanting cotton problem,  but cochineal has special challenges; it doesn’t like hard water and it is sensitive to pH.

So I have been working on what is the best way to mordant specifically for cochineal.  I have very hard water here, dilute limestone you could call it,   so even if I use distilled water for the dye bath, do I have to use distilled water for mordant and scour baths also?

The study mentioned above suggests that a tannin treatment can be used  make the colors darker and make them more light resistant. Cochineal has good light fastness but I wanted darker colors.  Here is my first study of tannin treatment, after scouring but before mordanting:

The scoured substrate was first treated with a tannin from pomegranate, then mordanted with aluminium acetate and then dyed with cochineal. From the left; substrate, tannin alone, then 4 with cochineal also.

The scoured substrate was first treated with a tannin from pomegranate, then mordanted with aluminium acetate and then dyed with cochineal.
From the left; substrate, tannin alone, then 4 with cochineal also.

The natural colored substrate is on the left, next is the the scoured substrate that has been treated with tannin from pomegranate, it actual color is mustard yellow.  I was expecting a much paler yellow beige color.  Could be that the pomegranate powder I have has deteriorated with age?  I need to try some fresh pomegranate tannin, but don’t have any at the moment. But I had already treated a bunch of skeins with this old pomegranate so I decided to continue to see what I could learn. The next 4 sample go from brown to dark red.  This little study has 10 baths involved.  When I try to  save time by treating a bunch of skeins at the same time and something goes wrong, such as the tannin is old, then a bunch of skeins have been ruined.   After I get some fresh tannin I’ll need to redo these samples. I have gone through 59 skeins so far  and may have more questions than when I started.  I think I will be dyeing all summer.

The point being that I have not been weaving much but dyeing a LOT.  I still have lots of work to do.  First I have to wind small sample skeins from the yarn I brought back from Oaxaca, a rather tedious task. Luckily I have a friend that will keep me company and chat while I wind them  and all I remember is the pleasant company.

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