Learning about indigo continues….
I often receive questions about indigo dye that fades very quickly on a textile. When I ask the dyer how long the textile was immersed in the vat the response is usually “1 or 2 minutes”. That is not enough time! Each immersion in the vat needs to be long enough to permit the indigo to penetrate into the fiber: at least 10-15 minutes. Otherwise the dye simply sits on the surface of the textile, making it susceptible to fading and rubbing off.
Recently, I completed a series of tests in which I experimented with much longer immersions in the vat. Immersion times in the vat ranged from 20 minutes to 20 hours. A longer dip encouraged more dye to penetrate the fibers. The results are worth observing and discussing. All samples were neutralized in a vinegar/water solution and “boiled” to finish and remove excess dye.
The most common method of achieving dark colors with indigo is multiple successive dips in the vat and there are definitely some advantages to building color in this way. Any unevenness of the dye will level out as the textile is immersed multiple times. This is especially important when dyeing large textiles in a small vat. (This is the reason why larger vats are better suited when dyeing large textiles; allowing the dye to reach more of the textile surface) If the vat is large enough that the textile can be immersed and exposed evenly to the dye, longer immersion times may be a practical approach.
My usual approach to dyeing textiles is using woven shibori. The textile is gathered with the woven “stitching” threads, making a compact “package”, and exposing the outside pleats of the textile to the dye uniformly.
Lately I have been experimenting with itajimi shibori (folded and clamped resists), where many layers of cloth might be folded multiple times. When using mordant dyes or fiber reactive dyes, the dye usually penetrates through the layers. When dyeing with indigo (10-20 minute immersions), the dye fails to penetrate beyond the outside layer and into the cloth within the folds, despite multiple immersions. When the immersion time was increased to 24 hours the dye penetrated ALL the layers – like magic. More time in the vat allowed complete penetration of dye throughout the textile.
Lightfast tests were performed on all samples dyed with extended times in the vat by exposing 1/2 of the samples to four weeks in a window with direct sunlight.
Note: When dyeing protein fibers, care must be taken with the pH of the vat, as the fibers can be damaged by long exposure if the pH is too high. Ideal pH for protein is 9.5-10.
The North Carolina Arboretum is hosting the second Growing Color Symposium on March 8, 2018. Michel Garcia will be our keynote speaker. Join us if you can!
Natural Dye: Experiments and Results 
Catherine: Thank you for this post! What kind of vat did you make? Do you neutralize the cottons as well as the protein fibers with vinegar/water solution? And could you explain “boiling” particularly for wool. Thanks again.
I neutralize all textiles, including cotton. When finishing cotton, I boil the textile vigorously for a few minutes. Wool and silk is heated to just below a simmer with a small amount of neutral detergent and kept at that temperature for a few minutes. It really does help to remove the unattached indigo on the surface.
Thanks Catherine. I’ve been using hot tap water on my wools and now I know I can make it even hotter. It’s also nice to know that leaving shibori pieces in longer helps get the dye into all the unclamped areas. It makes sense when I think about it. I guess the areas that are done are just done and the longer soak allows the indigo to reach those other areas. There is so much to learn about this wonderful dye!
Catharine, Which indigo vat did you use for the tests? The mysteries of indigo.. I wish I could join you in March.. I have another commitment then. Thanks for all you do with natural dyes… and your blog Judy
On Mon, Jan 22, 2018 at 3:55 PM, Natural Dye: Experiments and Results wrote:
> Catharine Ellis posted: “Learning about indigo continues…. I often > receive questions about indigo dye that fades very quickly on a textile. > When I ask the dyer how long the textile was immersed in the vat the > response is usually “1 or 2 minutes”. That is not enough time! Each ” >
HI Judy, The vat I commonly use in the studio is made with henna, although I have found these results to be consistent with all the organic vats, including the iron vat.
really helpful post, thank you……and I have the same questions as janette144…..
Thank you for sharing your experiments. I will definitely try soaking my next batch of silk scarves in the vat for 24 hrs.
Jane Spencer
Thank you for sharing your experiments. I will definitely try soaking my next batch of silk scarves in the vat for 24 hrs.
Jane Spencer
Hi Catherine, Great post. Thanks so much for sharing your journey with so many. It’s very much appreciated. love Allison
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Thank you Catharine, I am always learning new things from you about this Indigo journey! Thank you so much!
Thank you very much for this post. I learned a lot! If you have earlier post about Natural Dye I would love to get them!
All the best from Ragnhild Rise
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Fra: Natural Dye: Experiments and Results Sendt: mandag 22. januar 2018 kl. 22:55 Til: ragnhild.rise@sf-nett.no Emne: [New post] Indigo Dyeing: Time and Patience
Catharine Ellis posted: “Learning about indigo continues…. I often receive questions about indigo dye that fades very quickly on a textile. When I ask the dyer how long the textile was immersed in the vat the response is usually â1 or 2 minutesâ. That is not enough time! Each “
I’m glad to hear this was informative. You can look back on all the previous posts – each relates to natural dye in some way and many of them address the use of indigo as I continue the learning process.
Thank you for your indigo knowledge! When you say 20 hrs.;you mean leaving the cloth in the vat for 20 hrs. Or multiple dips adding up to 20 hrs.?thanks!Leigh
Yes, 20 hours in the vat.
Once again, Catharine such great information. i really appreciate your research. Barbara
Always good to hear from you Barbara! There is always something more to learn…and I am always humbled by what I don’t know.
Do you have a source for eucalyptus to dye with? I am looking for red ironbark eucalyptus leaves that I can purchase.
Jane Spencer
Sorry, Jane, I don’t. The only eucalyptus I use is from a plant or two that I grow in the garden each year in North Carolina. Most eucalyptus comes from Australia. Susan Fell McLean collects and sells some but I don’t know if she ships abroad http://www.gondwanatextiles.com/ . There are some varieties that grow in California but I don’t know much about them.
Fascinating post, Catherine. Many thanks for your detailed investigative work! Our knowledge grows…
Hi Catharine, I found this article so interesting. The long dip with the itajime is stunning!
I’m curious what your method for boiling to finish the cloth after dyeing is these days. Are you still boiling with bran and soap? And for how long? I’m working on a big new commission tapestry with lots of indigo so it has to be as good as I can get it.
Many thanks, Sara
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Hi Sara, I typically boil with just a bit of neutral detergent. The boiling assures that any unattached dye is removed and Joy indicates that it actually helps the indigo move deeper into the fiber.
I was actually dyeing an itajime piece when your post arrived to me. So I left it soak all night in the vat, and yes, I confirm that it makes a big difference. the dyes reaches all layers of the fabric. Thank you for sharing
Glad that the post was so timely! That information had escaped me for a long time….
Hi Catharine
Thank you so much for all the helpful replies to the comments…they are so useful. Sorry if this is a really basic question but when you make a small vat in a glass jar did you leave it with the lid secured on…just want to check incase it would make the glass crack if I do this.
Also any tips on where to purchase Henna?
Thanks so much
I usually just put a lid on loosely. I don’t think there is enough active fermentation to break the glass but you really don’t need a tight lid.
Konichi wa Catharine, This may be more helpful than you think especially when mentioning the size of the vat problem and extending the submersion time. I am thinking 1200 years ago, Tang Dynasty, and how production of indigo dyed wool was most prevalent in felt carpets. Four different blue varieties have been noted, so it must have been like pickling, or keeping an eye on a pet, with no need of costly heat source. I have seen some felts with an almost black indigo, but only used in details whereas the majority could be considered light to dark in four shades. A rare green most likely over-dyed. Your final point concerning pH and damage to cuticles would in my case results in inadequacy of felting capability. Am recommending this article to my research time. Looking forward to seeing you in June, when one of the team members will be giving the introductory 11ISS talk so we will have to try to get together in Arimatsu. Thanks.
Hi
I am so pleased to have all this information and all your research results in your blog so easily accessible. Thank you, thank you!
Heat and the 1,2,3 indigo vat. There seems to be no mention of how warm or how the vat is kept at one temperature (what temperature) over a 20hr dip.
Just keep the vat at room temperature. The vat is begun with very hot water in order to begin the reduction but should not need heating after that.
Thank you.
Another question …. I have a very large old galvanized wash tub, could I use it for my indigo vat??
So glad to hear you and Joy will be teaching at Maiwa. I’m hoping to attend.
Sharon
No, best to use non-reactive containers such as plastic or stainless.
Hi,I have a question.Being dyed several times with short immersion time and dyed only one time with long immersion time.Which one’s fastness of color is better?Thanks!
I can’t say for sure, as I have not tested it but I would guess that the long slow dips would enter into the textile better. I would suggest you try both and compare for lightfastness.
Aqueon has a submersible water heater that is good for maintaining the vat at a desired temperature. Better yet, Aqueon has different wattages for different sizes of vats. Their heater is non-reactive poly and is suction-cupped to the side of the vat, if placed vertically. https://www.amazon.com/Aqueon-Pro-Adjustable-Heater-50W/dp/B003C5JNXK/ref=pd_sim_199_5?_encoding=UTF8&pd_rd_i=B003C5JNXK&pd_rd_r=NS8D3PGG3SD0HW9TVP93&pd_rd_w=3ZAJq&pd_rd_wg=4nbNm&psc=1&refRID=NS8D3PGG3SD0HW9TVP93
That is exactly the one I use. They not only come in different wattages, but they are different lengths. Be sure that the length you order will be immersed in the vat. I find that they usually last through a winter season (or two). I’m sure that the alkaline environment is hard on them but It’s a reasonable price to pay to keep the vat viable through the winter.
Catherine, do you massage the bundle during that 24 hours? Or just let it sit? Thanks so much for sharing your research with us.
It depends. If the textile is dense, handwoven or very thick I might be inclined to massage it. On the other hand, if it is light, airy and I know that the dye will penetrate easily, there is no need. As will everything, experimentation with your own materials will tell you what is best.
Would this be applicable for a hydrosulfite/thiox vat as well?
I don’t have enough recent experience with the hydrosulfite/thiox vat to comment knowledgeably, but I would guess that long exposures in the chemical vat might be damaging to the fibers.
Hi, I’d just like to clear one thing up. You talk about immersion time and the number of immersions. I have always thought more immersions the best process, but I am wondering when you talk of 2 hours or even 20 hours of immersion time, is that one immersion or the total time of say 10 or 20 immersions? I expect it could be either, but I’d like to be sure. Recently I’ve been experimenting with 2 minutes in and 10 minutes out immersions, but many of them, say 10 or 20, and had reasonable results. I only tried this because it was a piece i had to hold semi-submerged in the vat and there was no way to do it except by hand!!
When I speak of long immersions (10 minutes or 10 hours) I mean that the textile is left in the bath for that long in a single immersion. I first began thinking this way after I visited the studio of a Japanese trained indigo dyer. He lowers the the fabric to be dyed into the vat and simply leaves it there for several hours. I realized that this approach might be expedient for production dyeing and fit the rhythm of the studio.
I wanted to know what affect these long immersions might have on my own dyeing. So I began to experiment.
When dyeing for long periods of time, you do need to be sure that the textile has even exposure to the dye in the vat. For that reason, the vat may need to be large and deep. I have experimented with various methods of immersion and now usually suspend textiles just below the surface from hooks and poles. Granted, it is very difficult to dye a large piece of yardage evenly in a small vat. Multiple dippings (oxidizing in between) also has the effect of evening out the dye.
It’s all a process of trying things and finding what works. I would be cautious with the 2 minute immersions – there might not be enough time for the dye to really penetrate the fiber. That’s when I experience low lightfastness.
Thanks, I kind of thought you might mean that. I’ll have to rig up a peculiar system for suspending this particular kind of job somehow. Bring on the arc welder maybe…
I guess that if you do ten one hour immersions it wouldn’t be wildly different from one ten hour immersion, but I’ll test it and see. I have a fairly large vat, a big 1 metre high terracotta pot, so I am not too worried about dye distribution.
And thanks for your post on finishing off indigo dyed material. I have been a bit concerned about some fabrics which really loose their soft feel after a lot of dips in a ferrous vat. I’ve been using citric acid to rinse them since it dissolves iron really well. I assume it does the same as vinegar in your method?
See you in Nagoya, I’ll search you out and say hello.
One of the problems with citric acid, is that it does not really dissolve and rinse out. It can cause problems with the textile later on. Joy is adamant about this one and I’ve seen evidence in cotton textiles – little holes where the textile was damaged. Vinegar (or acetic acid) is always safe, as it evaporates.
hello, if I want to get a really dark colour and must do multiple dyes do I use the same dye vat or must I mix up a fresh batch every time? Thankyou.
If you are inquiring about indigo, you continue to use the same vat, building up color slowly with multiple dips into the vat.
I know my comment is very late on this post, but it is absolutely a revelation! I’ve got some bandhani tied silk scarves from Maiwa that I’ve been afraid to dip in indigo thinking that it won’t move all the way through the layers… the scarf is folded in quarters. You have given me the confidence to do a long dip. Also, what a nice feeling it must be to gently set something in a happy vat and just walk away!
Thank a lot for sharing, teaching ans inspiring !!! It’s an immense joy for me to discover you blog !!! Best regards 🙂
Do you know a method to bring the pH down from 11.5 to the 9-10 required for dyeing wool yarn? I made a fructose vat, and it has been sitting for 7 days, reheated once, stirred a few times, and I dyed some cotton fabric in it, as suggested by Maiwa, where I bought the supplies. The pH remains the same, and I don’t want to ruin my wool! Thanks for your interesting blog, and I greatly appreciate any suggestions you have.
The pH of the indigo vats, particularly those made with the quick reductio process and lime, tend to have a very high pH. Eventually, this pH will drop, but that may be several days/weeks and the drop in pH may also cause the vat to to have insufficient reduction.
Another way to protect your wool is by adding dissolved animal hide glue or gelatin to the vat. Both of these are protein substances. The addition of the dissolved glue just before dyeing will will absorb some of the excess alkalinity (lime) and thus serve as some protection for the wool fibers.
I have dyed many a wool fabric or yarn in the quick reduction vats and I don’t always use the hide glue. There seems to be no damage to the fibers. I think that the high pH of chemical vats that have been reduced with thiox or sodium hydrosulfite are far more damaging to the fibers than these gentler sugar or henna vats.
Nevertheless, proper neutralization and finishing after the dyeing is very important.
Joy and I have instructions for hide glue addition in our book, and it is also available on the Botanical Colors Website