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.)