What to do with old stored dye solutions?

As part of my de-cluttering efforts, I’ve been sorting through my stock of stored dye solutions and deciding which to keep, which to use and which to finally discard. Sometimes the decision is easy, such as when the container releases a foul odour on opening, followed by “glops” of mouldy “gunk” when the contents are poured out. Actually, I am often relieved when this happens, because it means I can throw the contents away without feeling I’m wasting something precious. It’s more difficult when the only reason for throwing a solution away is because I just can’t motivate myself to use it up. This happens, for example, with old rhubarb leaf solutions. I know I’ll probably be able to harvest leaves, if I want to mordant with rhubarb leaf solution, and I’m far more likely to feel like making a fresh solution, rather than using up stored ones. So the old solutions can be poured onto the compost heap, although I’ll probably decide to keep one full container, just in case I need some before my plants have produced any leaves to make more. (Incidentally, if you feel hesitant about putting rhubarb leaves or solutions onto the compost heap, gardening experts now seem to agree that it’s fine to do this.)

Among the other stored solutions that cause me some heart-searching are oak-gall and walnut hull solutions. In the end, I’ve decided to offer these to other dyers in my guild, so for the moment I can avoid having to make a decision. However, if no-one else is interested in them, I’ll probably discard all the oak-gall solution, as I have enough oak galls to make some more and it’s not something I tend to use frequently. And I’ll probably decide to make some space in my shed by discarding some of the walnut hull solutions too, as I have dried walnut hulls and some walnut extract to fall back on anyway. These solutions will enrich the compost heap, I’m sure.

And now to the woad solutions I’ve found, all stored in 5-litre containers. (Details for making woad solution for storage are in my books and are outlined below.) Two containers are labelled “2008” and the contents look blue and have the characteristic woad smell. So I’ve decided these can be left and used at a later date. The other container doesn’t have a date on it and the state of the label suggests it may have been lurking in the shed for quite some time, possibly several years. On inspection, the solution looks a rather unpromising pale brown and it doesn’t smell “right” either. But I’m not prepared to throw it away without trying it out, as I know from experience that even the most unpromising-looking solutions can sometimes yield good results.

So I pour off the contents of the container and I can see that some of the blue pigment has sunk to the bottom or stuck to the sides of the container, leaving a pale brown liquid with some particles of indigo pigment floating in it. I check the pH of this liquid and it would appear to have lost some of its alkalinity. So I make a solution of washing soda dissolved in boiling water and stir this into the woad liquid until pH 9 has been reached. Then I return some of the solution to the container and shake it vigorously to try and dislodge some of the blue pigment from the sides. I also use a wooden spatula to scrape as much as I can reach back into the solution.  I decide to try out the solution, so I pour it into a dye pot and add more water to make enough liquid for the vat.



 This shows the solution, with the extra water added to make the vat.





Once the solution has been heated to about 50C and I’ve added sodium hydrosulphite to remove the oxygen, it starts to look more promising. The metallic-looking blue sheen that has formed on the surface indicates the presence of blue pigment, so I stir it gently to one side and then add 300gms of Wensleydale wool yarn and watch as the sheen disappears, leaving yellow liquid, through which the skeins are clearly visible. Then I leave the skeins to steep for about 20 minutes.



This shows the skeins steeping in the vat.






Then I remove the skeins and I’m pleased to see that they have dyed a good mid-blue, so I’m delighted I didn’t throw the solution away without trying it.



This photo shows the dyed skeins.






So what would I have done, if the solution had proved useless and the skeins had failed to turn blue? Well, I had already prepared for this possibility by making a solution of indigo powder and washing soda, ready to add to the woad solution in the pot if necessary. (I dissolved 3 teaspoons of washing soda in about half a cupful of boiling water, allowed it to cool slightly, then mixed in 3 teaspoons of indigo powder.) This solution will now be stored in a tightly-sealed glass jar until I decide to make an indigo vat. So instead of reducing my stock of stored solutions, I seem to have kept the situation exactly as it was, by using up one stored solution and then replacing it with another!

(Note on making woad solution for storage:

This is exactly like preparing a vat from fresh leaves but you stop the process just after whisking the liquid to incorporate oxygen. So firstly pour boiling water over the fresh woad leaves and leave them to steep for about 1 hour. Then pour off the liquid, remove the leaves and add washing soda until the colour of the liquid changes from brown to green (or until pH 9 or 10 is reached). Then whisk vigorously, or pour the solution from one container to another, until blue froth forms. Carry on whisking until this froth starts to become white again. Leave to stand until the froth has subsided (you can help by gently mixing the froth into the liquid but make sure not to lose any of it, as the froth contains the precipitated indigo particles) and then pour the liquid  into a airtight container with a well-fitting lid, filling it up until the liquid overflows slightly. Then fix the lid on tightly. When you want to use the stored solution, just pour it into a heatproof pot, heat it to 50C and add sodium hydrosulphite or thiourea dioxide (Spectralite or Thiox) to remove the oxygen. Then continue as usual.)

11 replies
  1. Marian
    Marian says:

    This is really interesting. I think I have a few bottles of logwood from last year. I don’t know if they will yield anything at all but I can not wait until the weather is a bit better and I can try it out!

  2. Marian
    Marian says:

    Me again. If you don’t mind I wanted to ask you a question: I’ve read around that tea can be used as a mordant. I have been looking in your books but at first glance I don’t seem to find anything on tea. Do you have any experience with tea (I guess you do!) Is it even light fast, tea?? I do tea dyeing a lot because it is quite easy. I dry and store used tea bags and then make one big pot of tea and simmer stuff there for a while. But as to whether it is light fast?
    Anyway, hope you are going alright!

    • jennydean.co.uk
      jennydean.co.uk says:

      In response to Marian’s query, tea bags could be used as a source of tannin for mordanting vegetable fibres and silk, although their tannin content is not as high as that of oak galls or sumac leaves. On the rare occasions when I’ve experimented with tea bags as a dye for cotton or linen fabrics, I found they gave variable, sometimes patchy, results. The results on wool were generally a dull beige.
      I believe a tea dye bath is sometimes used by antique dealers to “age” the appearance of lace and cotton & linen textiles (tablecloths etc) by giving them an “antique” creamy appearance & making them look less white and new.
      I’m afraid that’s all the information I can offer.

  3. Hanna
    Hanna says:

    Thank you for another very thought-provoking and informative post! I have a couple of vats moldering away in the back corner of my yard (pecan and walnut hulls, along with one or two desert plants) that I’ve been meaning to clean out for a while but didn’t have the heart to do so. This may be the inspiration I need to finally kick the buckets over!

    And, maybe, someday, if I’m able to get woad to sprout here this summer, I can try the preservation method you’ve described. Sounds very interesting.

  4. Jenn
    Jenn says:

    Tea can be used as a dye (it is actually a stain, not dye though), it is relatively light fast. Comparing wool and cotton from the same dye pots, the cotton seems to pick up the tannin and tea colors better than wool.

    The real benefit for tea for me is the tannin, as tea is a cheap source for it, especially if you are reusing tea leaves. Good mordant for browns and tans. Pomegranate and walnuts also have it (which is why you don’t need an alum mordant for fresh walnut to get a nice color), as do I believe some barks, so tannin is also a benefit of being a mordant that can be made locally.

  5. neki rivera
    neki rivera says:

    great post and very timely too.
    i’m in the process of clearing some of my stored dye liquors. and thinking what to do with last year’s fermentation indigo vats that have been standing outside in the cold and rain:) perhaps they can still be salvaged!

  6. Helen Melvin
    Helen Melvin says:

    Its a pity we don’t live near as I can never get enough oak galls for my black ink! Fantastic to know that the woad vat can last as long. I wondered if you could have scraped off the indigotin which had deposited on the bottom of the vat and saved it?

    • Jenny Dean
      Jenny Dean says:

      You are quite right about trying to scrape the woad pigment off & then using it as one uses indigo powder. Frustratingly, the neck of the container was too small & awkwardly positioned to allow me to do this with any of the tools I had available, as none was sufficiently flexible. So the best I could do was to scrape off as much as I could reach & then try with washing soda solution to dissolve some more. I suppose the lesson of this would be to find a container with a wider neck & a more flexible scraper!

  7. Leena
    Leena says:

    This was a interesting and fun post to read (as always).
    I have one bucket with japanese indigo liquid from year before last, and it is brown (the lid wasn’t tight at all), I thought the pigment is lost, but I haven’t gotten around to emptying it, now I will have to try to dye with it:)
    I also save many baths, and have buckets here and there and then forget what they are, I should label them!
    Indigo and woad baths are so “valuable” that those jars I know:)

    The bucket where I have iron liquid from last fall, is now really dark, almost black, and it was made of only iron powder and water, I have been surprised to see the color change so much.

    • Jenny Dean
      Jenny Dean says:

      I’ll be interested to know the results when you use your stored Japanese indigo solution. I’m sure the pigment will still be there but perhaps in powder form & sticking to the sides of the container. If you make sure to scrape the sides of the container well to get all the pigment, you should have reasonable results.
      I would suggest that you strain your iron solution well before you use it, to get rid of any solid bits. Some of my iron solutions look really “dirty” but are fine once I’ve strained off some “clean” solution.

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