The first batch of indigo was a small trial batch on 15L because I heard so much about the difficulties with indigo and that it was supposedly a lot trickier than e.g. madder and onion skin. As a low volume trial, I only dyed some swatches and some left over yarn that I had lying around. In my previous entry I covered the basics of indigo dyeing, look it up here if you’re interested.
From the left it’s wool, silk, wool, wool, store bought yellow wool and grey wool. Everything turned out pretty uneven but it’s not realistic to expect perfect result on the first attempt. Besides, it’s indigo, you can always re-dye it for a more evenly dyed fibre.
Considering the instructions for indigo batches I always use Sandström and Sisefsky (1970) for this purpose. Since I don’t know the exact chemistry behind this process (!) I use a linear model to keep the same ratio in each batch. That is, I just multiply or divide the value in the existing instructions to fit the fixed variable. The fixed variable differs from time to time, sometimes I have a finite amount of indigo, sometimes I have a certain amount of yarn I want to dye and sometimes there is a volume limit on the cauldron I am using. This makes me re-calculate everything before dyeing but that’s not a bad thing because I like to have time to think things through, which is something that I am forced to do in such cases.
As you can see, I try to write down the date, mark the fixed variable and then write down the other amounts used so that I would be able to re-do the exact same thing if needed. In that way, it’s easier to say that a certain hue can be made or if I would need to dye some more fabric or yarn in a similar hue.
Concerning the chemistry of the dyeing process, I aim to get a better understanding of the chemistry in time but this is a work in progress. If I am able to do that I think that it is possible to do several process optimisations, which would result in the usage of less material and heat but still having good water and light fastness in the dyed material. Using a linear model is often a very simplified solution, many chemical processes are not well represented by a linear model and it is possible that it’s the same case with the indigo dyeing process. I’ll get back to you if I find anything worth sharing.
The larger piece of wool fabric that you see to the left in the first picture was later on used as a lining for a 14th century womens hood, which is a comfortable use of an uneven dyed fabric since most of it won’t be seen anyway. Tablet-woven edges done using yarn in the same light blue hue from the same batch, just to keep up with the latest reenactment fashion ☆
My hood is made from leftovers so it’s a little lacking at some points but if you want an excellent tutorial for this hood you should check out Katafalks tutorial here.
I still haven’t done anything with most of the yarn since I don’t have any reenactment related ideas, suggestions are welcome. Worst case scenario, it’ll be used for modern knitting.
Smaller batches are always useful for learning and also very easy to handle so I’d definitely recommend it as a good starting point. Developing a habit of writing things down will also make it easier to backtrack your work, to learn from it and to know what kind of colour you will get from a specific setup. Notes are a superior tool in order to communicate methods and results to others; also, you don’t need to remember everything if you have it written down. Overall, information exchange and feedback is fundamental for improvement and to avoid having everyone repeating the same mistakes.
Combine this with a sample set of each batch and you will be on your way to greatness. Now get a fancy notebook and get going.
This is a short instruction of how to do an indigo dye; it is recommended that you look up further literature if you plan to do an indigo dye. If you understand Swedish, Sandström and Sisefsky (1981) is greatly recommended when it comes to plant dyeing.
As a chemist, I recommend the general use of glass wares because glass as a material is inert and will generally not be permanently stained or otherwise affected by chemical reactions. This goes ESPECIALLY for handling acids and bases. For the dyeing pot it’s stainless steel or enamelled pots, I myself use stainless steel and a smaller enamelled pot when the occasion calls for it. Iron and copper pots are also usable but will affect the outcome. Avoid aluminium.
I don’t know if this is necessary but I’ll write it anyway; NEVER use any equipment once used for dyeing in cooking. Some simpler things like alum might be easy to wash away but I’m lazy and don’t like meticulous cleaning so I use completely separate sets for everything, measuring and stirring included. I also greatly recommend taking notes on what you’re doing as well as pictures. Combine these two and you will have what is commonly known as a laboratory report. In that way, you don’t have to remember everything you did, for long and how it looked. The human mind is keen on forgetting things very quickly, especially if the process was successful. Writing things down will make it easier to share information or to successfully repeat the process. This is something I myself struggle with as I often wish I would take more informative notes of what I’m doing and why.
An indigo dye needs several chemicals and materials, e.g. table salt aka sodium chloride (NaCl), ammonia (NH3), 25wt% sodium lye aka sodium hydroxide (NaOH), sodium dithionite (Na2S2O4), denatured alcohol (I use T-sprit), indigo. In order to do this as safely as possible it is recommended to read up on every chemical BEFORE dyeing as well as reading the instructions thoroughly! Use the (Material) Safety Data Sheet, something that was mentioned earlier in this post, for each substance if you’re uncertain. If you feel comfortable with all of the chemicals above, how to store them and what to do in case of a spill or other accident, then go ahead.
It would be good to quickly mention the weight percentage of the sodium hydroxide; it’s supposed to be 25wt%, which means that if you want to have a stock solution of 500 gram (approximately 0.5 L since the density of water is 1000 gram/L) then you need 75% of it to be water and 25% of it to be sodium hydroxide. This is easily done by measuring 0.75×500=375 gram of water and then add 0.25×500=125 gram of sodium hydroxide. Keep in mind that this is a exothermic process (gives off energy, in this case heat) and that sodium hydroxide is a base so take care when doing this. If you’re uncertain about what I’m talking about, please read up on some elementary chemistry; it should be covered in most high school chemistry literature. If not, my literature recommendation on basic chemistry is Chemical principles by Atkins and Jones (2013).
In indigo dyeing, there is the preparing of the vat (where the indigo is) and the dye bath (where the vat and fibres are added and the actual dyeing takes place), so look at the instructions for both of these to make sure you have enough material for each step.The indigo vat can be done indoors for several reasons, mainly because of the lack of ammonia. The use of ammonia in the dye bath makes it unsuitable to do indoors unless you have a fume hood or equally efficient ventilation (a kitchen fan is usually not up to standard). Stay outdoors for the dye bath! Plan ahead.
Material: Glass jar with a tight shutting lid that holds the total fluid volume of the vat (in this case around 190 ml)
Something to stir the indigo vat with (it will be stained if not glass or stainless steel)
Pot that can be filled with enough water to cover the glass jar
10 g indigo powder
Denatured alcohol (I use T-sprit)
165 ml 50°C water
16 ml NaOH 25wt%
10 g Na2S2O4
Put the indigo in the glass jar and add a small amount (10-15 ml) of denatured alcohol, enough so that you can stir the indigo.
Add 165 ml of 50°C water, stir.
Gently add the Na2S2O4 and stir.
Screw the lid tight shut and immerse the glass jar holding the vat in a 50°C water bath for 1 hour. Put a cork coaster or something similar under the jar to avoid it being in direct contact with the heating source and as such avoid having an uneven temperature in the vat.
Done. The vat will be green-brown in colour.
And there you go. Now you have a vat! You don’t need to use all of the vat at the same time, you can save some for another time. Just make sure to save it in a tightly shut glass jar with a minimum of air in it. Write the amount of indigo and the date on the vat so you know what’s in it and how old it is.
In order to have different shades of blue you can always use more or less indigo, 10 gram would give a somewhat lighter blue.
A pot/cauldron that can take 16 L of water PLUS additional fabric and/or yarn without being crammed
A stick or something to stir with that is long enough so that you can comfortably stir the pot at the bottom without dipping your hand in the bath
Thick, long protective gloves
About 1000-2000 gram of fibre depending on the wanted colour depth and intensity
(Graduated measure cylinder (mätglas) is not necessary but really good to measure ammonia and sodium hydroxide in)
Dye bath: 16 L water
70 ml ammonia
30 g sodium dithionite
200 g table salt
200 ml vat
Heat the water to 50°C, make sure you have attained a stable temperature as the temperature greatly affects the outcome (deviation at most +/- 5°C).
Add the ammonia (avoid the vapours as much as possible). From now on only use protective gloves when handling anything containing liquid from the bath.
Add the sodium dithionite. After this you should avoid adding air/oxygen in the bath. Stir gently.
Add table salt and wait until the salt is dissolved in the dye bath. If not properly dissolved, the salt will gather at the bottom of the pot and leave dark stains on the fibre that comes in contact with it. To stir the bath in order to more quickly dissolve the salt is fine, just do it carefully in order to avoid stirring down unnecessary amounts of oxygen.
Gently add vat. The surface of the dye bath should have an oily look to it.
Prepare an appropriate amount of fibre (100-500 g) by immersing it in lukewarm water (about 30-40°C) for about 5-10 minutes before dyeing so that it won’t float to the surface when it’s dipped in the dye bath and to avoid dry spots.
Remove the wet fibres from the lukewarm water and remove excess water from fibres by gently squeezing it.
Carefully add the fibres to the dye bath. Avoid creating air pockets in the fibre that will add unnecessary oxygen to the bath or limiting the fibre access by having tangled fibres. Untangle everything and make sure that every part of the fibre is in contact with the dye bath and kept under the surface of the dye bath throughout the dyeing process.
Wait 5-10 minutes. The fibres will look yellow in the bath.
Remove the fibres slowly from bath, avoid dripping as oxidised droplets will add oxygen to your dye bath. The yellow-greenish look on the fibres will slowly turn blue when in contact with oxygen.
Let the fibre oxidise for about 20 minutes to see to what extent the fibre has been dyed.
If wanted, repeat step 8-11 up to a totalt of 4 times for deeper hues and shades.
Use appropriate tools when removing the fibres from the bath. Always wear protective gloves. Protective glasses can also be used if deemed necessary.
Rinse fibres thoroughly after dyeing. Sandberg and Sisefsky (1981) recommends an acidic after wash using acetic acid to increase the general rubbing fastness of the dye.
When dyeing loosely woven wool, it is possible that there will be a shrinkage because of the temperature of the bath. To avoid this, test the shrinkage of your fabric beforehand and add shrinkage allowance accordingly.
Some additional notes on indigo dyeing:
Don’t be in a rush. Take your time, read and think things through. Prepare it in several steps, do the calculations one day and then dye another day. It usually takes me half a day to do one batch of indigo dye and I usually do the calculations the day before.
Not happy with the first result? Then just redo it, an intense indigo dye can save the blotchiest of fabrics.
Make sure you always have some extra fibres for swatches so that you can check that the dye bath gives the colour you wanted. Just remember to wait 20 minutes so the swatches are properly oxidised and thus representative of the end result.
If you get a stain of indigo powder somewhere, just clean it up using a paper tissue with denatured alcohol. But if you get a stain of indigo vat somewhere then there is no helping you. Sorry. To avoid this, be careful and keep a clean working area and remove everything that you could not handle being stained. Wear working clothes, you will get stains on your clothes.
Concerning historical sources of indigo for the 10th century, it is the same dyestuff in both woad and indigo; indigotin. According to my understanding, it is at the moment not possible to distinguish the indigotin source in older fabrics and findings even though it is probable that the main source of indigotin in the Nordic countries during the 10th century is woad. As an example, the indigotin found in the Mammen grave is said to be either woad or indigo (Hägg, Inga et al., 1991). On a different note, madder is also found at Mammen even though there are no evidence of the cultivation of madder in Scandinavia at that time. The dyestuff, procedure and result is the same for both woad and indigo; the main difference right now is that indigo powder is a lot cheaper than woad powder which unfortunately makes a lot of difference for me. But then again, the rest of my reenactment gear is not on the level that the breaking point of its authenticity would be the origin of the dyestuff. But when it is, I’ll do something about it.
Currently, I think that the trickiest part with indigo dyeing is knowing when to stop. At some point, you will not have enough indigo and/or too much oxygen in the bath and that will make the dyeing uneven or without effect. But exactly where that point comes is something I’m currently trying to figure out. Experience is key.
Keep in mind that the above, numbers and all, is more what you’d call “guidelines” than actual rules.
Happy dyeing y’all.
Atkins, P.W., Jones, L. & Laverman, L. 2013, Chemical principles: the quest for insight, 6th, International edn, W.H. Freeman and Company, New York.
I was going to wait a while before doing this kind of post but I was struck with sudden inspiration when I stumbled upon a Facebook group that focuses on plant and mushroom dyes. What is plant dyeing? Or, as it sometimes is referred to, natural dyeing?
Wikipedia is generally considered as an unreliable source but it somehow reflects society and the general public, and as such they say the following: “Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berries, bark, leaves, and wood—and other biological sources such as fungi and lichens.”
The alternative to plant dyes is synthetic dyes which are dyestuff that is not naturally occurring. The first synthetic dye was Mauveine in that was synthesised in 1856 and subsequently launched on the market in 1857. Even though picric acid was prepared as a dye as early as 1771, the foundation of the synthetic dye industry is generally attributed to the Mauveine synthesis and commercialisation (Christie, 2001). Before that point, all dyes were derived from natural sources.
But today plant dyeing seems to have a unique meaning only known to the user themselves. The general consensus is that fibres are being dyed but the means of doing it varies. For some, it means using plants for dyeing; for others, it means only using natural sources they can harvest out in the nature by themselves to dye with; and for a few it means to dye only using things with trivial names (incorrectly but commonly referred to as a “chemical free” process). I will try to avoid going into semantics about what is and is not a chemical by posting a link to this blog post about “What is – And What Isn’t A Chemical?“. As much as I’d like to tell you everything, I don’t have the time (and besides, who says you’re going to believe me?). But if you DO believe me, let me sum things up by saying that every material is a chemical, even if it exists in your home and has a trivial name.
To use a plant dye example; the chemical Ca(OH)2 is commonly referred to as slaked lime, which is constantly presented as an alternative to the chemical ammonia, NH3, in indigo vats. Unfortunately, they are both chemicals so if your aim is to do a dye without chemicals you have failed to understand the fundamentals of dyeing (and chemicals). Although, there are other reasons to use Ca(OH)2 instead of NH3 and vice versa but replacing one with another in the hope of becoming chemical free is futile work. Even that handmade natural oak-spirit-soap you bought at the last Carpe Diem-fair is made out of chemicals; even though the individual who sold it to you guaranteed it was not. There is no way around it. Minerals are also naturally occurring (Richardson, 1997), which makes copper sulfate, Cu(SO)4, legit as a plant dyeing material if we go by the the definition of plant dyeing (plants, minerals, invertebrates; derived from nature; naturally occurring etc.). And as such, we have the conspiracy unfolded right here, similar to when Frank Thorn realises the plot twist of the movie Soylent Green;
Nature is chemicals! They’re making chemicals out of nature. Next thing they’ll be synthesising organic molecules themselves. You’ve gotta tell them. Chemicals are naturally occurring!
But really though, I don’t think this comes as surprise for anyone (neither did the soylent green revelation!). I mean, where else would chemicals come from, the highly unnatural space? And, now that we think about it, are we sure that space isn’t natural as well? Anyhow, I do feel the need to mention that there exists a general idea of what is and what is not chemicals even in the field of chemistry; because we are also, believe it or not, a part of society and its norms. It is considered childish and unnecessary to refer to everything as chemicals all the time because it’s a basic fact which tells us nothing new. But on the other hand, in communication you have to specify what you’re talking about and herein lies the difference; you can’t just say chemicals if you want other people to understand you! You should explain what chemical you’re referring to, which isn’t that much of a stretch really since you probably have one in mind already.
I don’t believe you! If everything is chemicals then how do I know what is toxic and what is not?
In case you didn’t know, table salt can be toxic to humans. Apple seeds contains cyanide and cyanide is also toxic to humans (Holzbecher et al., 1984). All in all, there is stuff like this everywhere and about everything can be toxic, it’s only a matter of concentration and dosage. The thing is, you don’t digest or wash your eyes with washing powder, hairspray, rubber, deodorant, hair dye, thinner, oil, nail polish or shampoo because you know that it might not be good for you. You seldom use these things outside of its intended purpose because you also know that it might become weird. And don’t get me started on people who smoke and drink but are afraid of chemicals eventually being hazardous… Nevertheless you don’t hesitate to use it in your everyday life. But for some, reason, this kind of thinking completely disappears as soon as the word chemical is involved. Which is weird, because it’s basically the same things going on there. There ARE information and literature on how to plant dye and what to use and how. Follow those instructions and you’d be fine. Another source of information is to check out the (Material) Safety Data Sheet (M(SDS)) for a certain chemical. Here is a MSDS for table salt.
A short, but very unsatisfying, summary would be to implore you to use your common sense and you’ll be fine. If you still want more I’d recommend to study toxicology.
But there is too much information, I can never remember any of this!
You don’t have to, most people use books to write down the most important things and there is always the internet to enlighten us.
Why did you have to make everything difficult, my way of thinking and evaluation is much easier!
I didn’t make anything (except this pesky blog), nature did.
But I am sure that people used only onion skins before the first synthetic dye, none of these mordants and acids! Those are all 20th century ideas!
I am not so sure. Unfortunately, as we often do in historical reenactment, we lack a lot of sources. Though one source that we do have is from a handwritten manuscript from around 1860; that is only a few years after the first synthetic dye was created and the processes described in manuscript involves no synthetic dyes. In fact, all these recipes described would soon be abandoned for the much more efficient and less costly synthetic dyes (Sisefsky and Sandberg, 1979). The manuscript has one example for dyeing blue wool yarn and it involves potassium cyanide (KCN), hydrochloric acid (HCl), disulfuric acid (H2S2O7), potassium aluminium sulfate (alum, KAl(SO4)2) and potassium bitartrate (cream of tartar, KC4H5O6). How’s that for a cocktail? Kind of put our modern concern about using a 20wt% alum mordant at a shame. Of course this doesn’t mean that this is what was used in the earlier centuries but we can at least say that these chemicals are not exclusive to the 20th century and their use in plant dyeing processes precedes the 19th century development of the synthetic dye industry .
I dye only using onion skin! I am chemical free.
Pelargonidin is what is in the dyestuff of onion skin (Uddin, 2014). If you’re not using a mordant, it would be sufficient to just say that you’re dyeing without using a mordant.
Surely I use less hazardous material than in the industry? My environmental impact has to be less than if I’d buy the industrially dyed material?
The current industry has had several iterations, process optimisations and experience which generally makes the industry a lot more efficient than a single individual with little to no technical equipment and experience. Most developed countries also have a lot of regulations that is to be followed regarding the process and its emissions, no one will measure your own amount of trace metals in your plant dyes (Griffiths, 1984). As I previously mentioned, synthetic dyes are far more efficient than plant dyeing which means you’d generally consume less resources using synthetic dyes compared to plant dyes (Sisefsky and Sandberg, 1979). The difference here is to how to view the emissions; if you compare emissions and resource consumption per kilogram of dyed material, the industrial dye would probably be using less resources. A common theme is that there is a lot of transport involved in production, which is not good thing for the environment but also makes calculations more difficult. Even so, there are ways that these are accounted for (an example would be the Life Cycle Assessment) but you will always have to limit the analyse. I’ll try to explain this with an example; if you’d dye yarn that was made at the farm next door you’d be responsible for less emissions than if you’d buy imported yarn. But then again, if the sheep that made the wool at the farm next door lacks food in the pasture and needs to support feed and then that food needs to be transported there, should that transport be included in the emissions for the yarn? And where was that food grown and using what fertiliser? As you probably understand, this thinking can derail pretty quickly but I hope you see the problem with deciding a number for any of these emissions and impacts which is also why you should be critical to anyone producing such numbers, what is included and what is not? Often the numbers are in favour of whoever is presenting them so my advice is to be critical.
A summary of this would be to say that it’s impossible to know but an individuals plant dyeing process is probably more inefficient than the industry and has an unknown quantity of residuary chemicals in it (unless you analyse every batch, which would be cool but very expensive but at least you’d know what you’ve got). The industry can, of course, also have an unwanted quantity of residuary chemical but this is why we invest in quality and try to only buy fabrics and clothes from countries with regulations and decent working conditions, right?
My dyes DO become resistant to both light and water if I do it using only the dyestuff like blueberries/lupins/beetrot and no mordants!
No, they don’t. What happens is that you get a dyed material that WILL be drained of colour when exposed to water or sunlight (Burkinshaw and Kumar, 2009; Dumitrescu et al., 2008; Waheed and Alam, 2004). If you keep the dyed material away from water and sunlight things then you’d be fine but you’d also be living in a very dry and dark place. If you aim to be eco friendly, natural, climate considerate, environmental friendly or whatever buzzwords you use in justification then consider both the time, energy and work that you put into this. If you’re using any kind of heating in the dyeing process you are literally wasting energy and time; not to mention if you use wood as a fuel for heating the bath which has a LOT of exhaust gases that are harmful and currently not very popular (Bari et al., 2010;van Lith et al., 2006; Tissari et al.,2007).
I only use plant dyes in a cold bath and using sunlight so I am the most environmental friendly dyer there is and I am always pleased with my dyes and colour hues!
Good for you, get back to me when you can dye 2 kilograms of heavy wool evenly with a deep colour intensity while also getting water and light fastness in a cold water bath at pH7 using only dyestuff. Snark aside, if you HAVE achieved something like what I just said in a reproducible and controlled manner, please do share it with the world (that shit would be Nobel prize worthy)! That would be an amazing feat and of great benefit to the whole planet.
The question to ask in these cases is, if all kind of processing and chemicals are to be avoided at all costs then why dye it in the first place? The most natural way to avoid any kind of dye process is to NOT dye. Personally, I think that the natural colour and hues of wool is superior to many other hues, this is why a large part of my reenactment kit is non dyed wool. If you completely want to avoid any kind of chemistry happening then plant dyeing, or any kind of dyeing, is not for you. And before you even think it, there is nothing like good or bad chemistry; nature doesn’t work that way. Endless energy consumption is something to be avoided as well as pollution. Water is a resource and electricity doesn’t spawn spontaneously at the energy company, globally it is often a result of combustion (often coal) and somewhere there is a exhaust coming from that energy production. Is it worth the time and energy if the result will fade within a month?
On the other hand, there are several other things you can do if you want a more sustainable lifestyle. Some examples would be to eat less meat, promote local farms and production, don’t throw away food, travel less (unless by foot, bike or sailing), recycle, repair, invest in quality and so on. And my primary advice is to consume less. Simply put, buy less shit. Remember, it’s not a bargain if you don’t need it.
In the end, however, everyone does as they please but be aware of what you’re doing and the reasons for doing it. It is totally ok to plant dye for your own sake, and peace of mind; I encourage that since that is what a hobby is about! But don’t do it for the wrong reason or try to claim the moral high grounds by saying that it’s more natural (what even is natural? Infant deaths, scurvy, polio, venomous snakes, anaphylactic chocks, cyanide, dental cavities, space?) or without chemicals (IT’S NEVER WITHOUT CHEMICALS!). Instead, to specify what you’re avoiding and for what reason would be a better way of communication if you want to show some sort of situational awareness and at the same time be understood by other people.
Griffiths, J. 1984, Developments in the chemistry and technology of organic dyes, Blackwell Scientific, Oxford.
Holzbecher, M. D., Moss, M. A. & Ellenberger, H. A. (1984), ‘The cyanide content of laetrile preparations, apricot, peach and apple seeds’, Journal of Toxicology: Clinical Toxicology 22 (4), 341–347. PMID: 6098693.
van Lith, S. C., Alonso-Ramírez, V., Jensen, P. A., Frandsen, F. J. & Glarborg, P. (2006), ‘Release to the gas phase of inorganic elements during wood combustion. part 1: development and evaluation of quantification methods’, Energy & Fuels 20 (3), 964–978.
Sisefsky, Jan & Sandberg, Gösta (1979). Receptsamling från Schwartzska färgeriet i Borås efter handskrivet original från 1860-talet på Borås museum. Borås: Borås museum
Richardson, H. W. (1997), Handbook of copper compounds and applications, CRC Press Tissari, J., Hytönen, K., Lyyränen, J. & Jokiniemi, J. (2007), ‘A novel field measurement method for determining fine particle and gas emissions from residential wood combustion’, Atmospheric Environment 41 (37), 8330 – 8344.
Uddin, M.G. 2014, “Effects of Different Mordants on Silk Fabric Dyed with Onion Outer Skin Extracts”, Journal of Textiles, vol. 2014, pp. 1-8.
Waheed, S., & Alam, A. (2004), Studies of some natural dyes, JOURNAL-CHEMICAL SOCIETY OF PAKISTAN, 26, 255-263.