FEEDBACK FRIDAY: This Week in Natural Dye Questions

This week: Urine vats, keeping your indigo vat alive and can you fix color with sea salt?

Every week, we are emailed with questions from our natural dye community asking simple and complex questions that we thought might be worth sharing. Of course, all of your burning questions are answered by natural dyer in chief, Kathy Hattori, Founder of Botanical Colors.

Does Aboubakar Fofana use the urine vat? Also, I see little evidence ever of indigo dyers using any devices to keep the vat warm, which is something I consider the ticket to fame and fortune any more. Although I have to admit I am just winding some yarn that I dyed with indigo for socks and regardless of endless rinsing and vinegar soaks I still get some crocking. Is it just unavoidable?

Wow, these are a lot of questions to unpack.  1.  No urine vat, and he does not use it, ever.  2.  We keep the vat warm (85 degrees) by wrapping in blankets as evenings in Seattle are in the 50s and 60s in the summer.  3.  Crocking is avoidable, but the entire indigo process contributes to good dyeing, so it’s difficult to pinpoint what caused your problem.

I recently made a 6 gram fructose indigo vat (8 gallons), using the method Aboubakar taught last summer here in Oakland. It went well and is dyeing beautifully, but a bit on the lighter side than what I would like. A question about this vat: I don’t recall Aboubakar saying whether it should be stirred on a daily basis/or every now and then to activate the indigo? and should it be stirred gently or more vigorously to bring up the flower (as my flower disappeared after using it)?

The indigo and calcium mixture is the sediment layer on the bottom of the vat and should be stirred before you put the vat to sleep and reuse it.  Normally, the flower reappears as well when you use this method. It is a vigorous stirring.

I am interested in creating a ferrous vat, as I used one recently and it dyed very strong and I have heard it works well for cellulose fibers (I work with paper). Do you have directions on preparing a ferrous indigo vat?

The ferrous vat is a type of 1-2-3 vat.  Use the following proportions of 1 part indigo, 2 parts ferrous, 3 parts calcium. This is the formula I learned and other dyers use 1 part indigo, 2 parts calcium and 3 parts ferrous.  I have not compared the two recipes yet, but you may want to experiment and see what is best for you.

Would you recommend it if I made a ferrous indigo mother and added it to the fructose indigo vat?

We have inadvertently done this in a workshop and I did not notice that this was a problem, so again, experiment and see if the results are what you are seeking.

I am new at natural dyeing, and want to dye with the most sustainable-chemical free dyes possible, and I would love to only use your natural dye extracts, and maybe try to fix the color with sea salt. Is this possible or will the colors disappear fast from my fabric? I’m using 100% cotton.

Salt (like ocean salt or table salt) is used with soda ash to fix fiber reactive (synthetic) dyes and is not a common process for natural dyes. So don’t rely on sodium chloride (table salt) or sodium sulfate for natural dyeing. In the synthetic dye world, these ingredients are quite polluting because they are used in large quantities.

Cotton fibers have the least amount of affinity (ability to bond) with natural dyes, but it is possible to use cutch by itself because it contains tannins, and tannins do have affinity with cotton. The general process is to dissolve the cutch and add to a dye pot, then add your well-scoured fabric to the dye and simmer the fabric for 2-3 hours because the particular tannin you need to set the dye benefits from a long time simmer. The exhaust bath may be re-used. If you are using a solar cooker, that would go a long way toward working sustainably.