Actually, we might have saved ourselves a good deal of trouble if we had been able to extract leucoindigotin from woad or indigo directly. Unfortunately, the indigotin is oxidized by the air very quickly. But we can use the same idea to extract dye from black walnuts if we are able to collect them when they have just fallen from the tree. The walnut tree has been kind enough not only to produce the dye juglone, C10H6O3, in its colorless, water-soluble state, but to package it in an air-tight container. I am speaking, of course, about the hull of the walnut itself. When the nuts fall in the fall they are initially soft and green, but after they have been lying around for a few weeks, the air oxidizes the juglone and the nut becomes hard and brown. If you are able to harvest black walnuts as soon as they fall from the tree, you will be able to make a beautiful brown, colorfast dye with no mordant and no urine required. You will be pissed at yourself if you miss the harvest.
Material Safety
Biological hazards tend to be far more insidious than chemical ones. You see, one molecule of even the most toxic chemical is absolutely harmless. Such a molecule might react with one of your molecules, but you have so many that it makes no difference. With a chemical compound the dose makes the poison; a larger dose is more hazardous and a smaller dose is less hazardous. Biological hazards are not like this at all. You know from making mead that one yeast becomes two, two become four, and so on until the mead is chock full of them. If you choose to ferment urine, the bacteria behave the same way. Of course, you have been exposed to these particular bugs all your life, so you have some immunity. Nevertheless, it is a good idea to wash your hands regularly, particularly when you have been brewing your own juices.
for each of these materials.
Your most likely exposure is eye or skin contact. If you get some in your eyes, you should flush them with cold water and go to the emergency room. Exposed skin should be washed with soap and water. Be aware that sodium hydrosulfite will bleach clothing. Be aware that walnut hulls will stain skin.
You should wear safety glasses and rubber gloves while working on this project. Leftover dye solution may be washed down the drain.
Research and Development
You are probably wondering what will be on the quiz.
• You should know the meanings of all of the words important enough to be included in the index or glossary.
• You should have studied the Research and Development items from Chapter 6 and Chapter 8.
• Know the equation for the reduction of idigotin.
• Know the equation for the oxidation of leucoindigotin.
• Know the equation for the conversion of urea to ammonia and carbon dioxide.
• Know the hazardous properties of indigo, walnut hulls, sodium hydrosulfite, and urine.
• Know why humans wear clothing and why dyes are so important.
The Stockholm Papyrus which began this chapter contains 154 recipes, of which I have chosen only a wee sample. Indigo will remain the number one dye even down to modern blue jeans. Progress in dye technology will come in dribs and drabs until the eighteenth century, when a new way to dissolve indigo gives a leg up to the infant alkali industry. Cheap alkali, in turn, will relieve a soap industry starved for soda. Industrial waste flushed out of the alkali trade will become the mainstay of the bleach industry. All of this in the service of clothing so that we can tell the whiz-kids from the pee-ons. Now, if you are dyeing to get started and you cannot hold it any longer, urine in for a treat.
Notes
[1] Reference [91]. [2] Reference [92].
12.3.
If you are going to dye indigo the old fashioned way, you will need to collect some urine. Urea comes from the metabolism of protein, not from drinking beer, so if you are drinking heavily to make more water, you have your leg up the wrong tree. Just let it flow naturally; you only need a liter or so and you can collect it in our old friend, that twenty- first century gourd, the 2-liter soft-drink bottle. Be sure to label it or someone may get a bit of a surprise. Put a few blades of grass into it to inoculate it with bacteria and then leave it outside in the sun. The time needed for fermentation to begin depends on the temperature. It will go quicker in the summer than in the winter. Unlike yeasts, bacteria need air so leave the top off your bottle. Your vat is ripe when you can smell ammonia, usually after a few days.
Once ammonia is being produced, grind 1 teaspoon (approximately 1 gram) of indigo in a mortar and pestle with a few teaspoons of water. You want the indigo to be as fine as possible because bacteria have tiny little mouths. Add your ground indigo to the bottle and gently swirl it to distribute the dye without adding too much oxygen. The fermentation will be most active when your bottle is warm so let the little fellows have their day in the sun. The solution will be dark blue when you first add the dye, but it should become pale green once the bugs get going.
If all is well, you should have a pale green vat with a blue scum floating at the surface. If not, there are several things that might have gone wrong. First of all, your vat should smell of ammonia. If not, add 1 teaspoon of household ammonia, swirl to mix it in, and wait another day. Some household ammonia has soap in it; you do not want that kind, you want clear ammonia. Check your vat each day, adding ammonia 1 teaspoon at a time until it smells as it should.
If your vat smells of ammonia but remains blue, then perhaps your bacteria are starving; give them a teaspoon of honey to eat. Fermentation should pick up and the vat should turn green in a couple of days. If not, then either a contamination from your dye or something else has killed your bacteria. Give it a few more days to make sure, but if it does not pull itself together I can only advise you to start over with a fresh bottle.
Once your vat is in order it is time to dye your yarn. Wash your woolen yarn, presumably that which you made in Chapter 6, with plenty of soap and water, rinse the soap out, and place it gently into the vat, trying to add as little oxygen as possible. Use a stick or stirring rod to keep the yarn beneath the surface and let it soak for 10 minutes or so. Then
As with a mead, it is possible to keep the vat going by adding food and nutrients. If the vat turns blue and no longer smells of ammonia, you need to add more urine. If it turns blue but smells of ammonia, you need more honey. And if it is pale green and ammoniacal but your blue is getting wimpy, add more indigo.
Figure 12-1. Dyed in the Wool
I realize that not everyone is comfortable handing precious bodily fluids. For you uriphobes, I am pleased to provide an alternative indigo vat which replaces the bacteria with a chemical reducing agent: sodium hydrosulfite. You will learn all about bleach in Chapter 25, but for now all that you must understand is that there are oxidizing bleaches and reducing bleaches and that sodium hydrosulfite is of the latter type. So if I may continue, you should run 100 mL of hot water (50?C, 120?F, no hotter) into a small bottle and add 4 mL of household ammonia to make a kind of faux-pee. Grind 0.2 g of indigo with a little water as before and add it to your vat. Now add 0.4 g of sodium hydrosulfite, which may be purchased as "color remover" wherever dyes are sold. Gently swirl until the hydrosulfite dissolves and let the vat rest. Within 10 minutes or so, the color should change from deep blue to pea green. If not, place your bottle into a pan of hot water as a kind of makeshift double-boiler or bain Marie. Swirl the bottle gently until the color changes from opaque blue to transparent green, as shown in Figure 12-1(L). You may now use this hydrosulfite vat in the same manner as the urine vat for dyeing yarn. The hydrosulfite vat may be "kept going" similarly to the urine vat. If you can no longer smell ammonia, add some. If the vat changes from green to blue, add more sodium hydrosulfite and re-warm it by swirling the bottle in a pan of hot water. And when your blues lose their hues, add more indigo.
Black walnuts produce a wonderful colorfast brown dye without the muss and fuss of the indigo vat. To dye 20 feet of yarn or so, you will need 5 or 6 walnuts freshly fallen from
the tree. Now, you are not interested in the nut itself; what you need is the green rind which surrounds the nut. With a knife, peel the rinds from your nuts and place them into a pan or beaker with about 1 liter of water. The good stuff is in the juice from these rinds, so if you can squeeze the juice into the water, so much the better. Now, if you work without gloves you will notice in an hour or two that your hands are stained brown even though the juice was green. You are probably thinking that the colorless juices have been oxidized by the air to produce dark brown, insoluble juglone on your hands. If so, you have indeed cracked a tough nut. This is precisely what we would like to have happen to the wool, but if you do not wish to dye your hands, you had better wear dishwashing gloves.
Heat your rind-water on a stove or hot-plate until it comes to 60?C or 140?F. Any hotter than this may damage the wool. Wash your woolen yarn with soap and water, immerse it in the hot dye-bath and let it soak for half an hour or so. Remove the yarn from the dye and let it air out overnight. It should be dark brown and colorfast the following day. If you would like to dye wool black, dye it first in black walnut and then in indigo.
There is a movement these days to recognize the contributions of women to science. The textile arts have provided an important driving force for the development of chemical industry, as subsequent chapters will show. For now just remember, "It may be the clothes that make the man, but it is often the woman who makes the clothes."
Quality Assurance
On the other hand, if your dye washes out with soap and water, you've just been piddling around. Break off a few inches of your colored yarn and tape it into your notebook.
Chapter 13. Theophilus (Glass)
If you have the intention of making glass, first cut many beechwood logs and dry them out. Then burn them all together in a clean place and carefully collect the ashes, taking care that you do not mix any earth or stones with them. After this build a furnace of stones and clay, fifteen feet long and ten feet wide,… When you have arranged all this, take beechwood logs completely dried out in smoke, and light large fires in both sides of the bigger furnace. Then take two parts of the ashes of which we have spoken before, and a third part of sand, collected out of water, and carefully cleaned of earth and stones. Mix them in a clean place, and when they have been long and well mixed together lift them up with the long-handled iron ladle and put them on the upper hearth in the smaller section of the furnace so that they may be fritted. When they begin to get hot, stir at once with the same iron ladle to prevent them from melting from the heat of the fire and agglomerating. Continue doing this for a night and a day.
Meanwhile take some white pottery clay, dry it out, grind it carefully, pour water on it, knead it hard with a piece of wood, and make your pots. These should be wide at the top, narrowing at the bottom, and should have a small in- curving lip around their rims. When they are dry, pick them up with tongs and set them in the red-hot furnace in the holes made [in the hearth] for this purpose. Pick up the fritted mixture of ashes and sand with the ladle and fill all the pots [with it] in the evening. Add dry wood all through the night, so that the glass, formed by the fusion of the ashes and sand, may be fully melted.
— Theophilus, On Divers Arts, ca. 1100 AD [1]
13.1.
Have you been observant, my brothers and sisters? Have you chosen to see things for yourself or are you afraid to touch what might burn your lily-white fingers, to taste what might upset your sensitive stomach, to smell what might clear your stuffy sinuses, to hear what might offend your timid ears? Did you stop to examine the lining of your crucible in your haste to retrieve your nugget of bronze, or did you notice that the slag had given the interior of the crucible an amazing glossy finish? If so, you have seen what went unappreciated by generations of potters and smelters until I attached significance to it.
It was in the early days of smelting technology, 4527 BC, if meme-ory serves, a millennium before the Bronze Age began in earnest. I had been raised to smelting from early childhood, sorting ores, making crucibles and gathering firewood for the furnace. I pestered my father and brothers constantly with questions and unsolicited advice. "Why
is the inside of the crucible black while the outside is white?" "What happens if you leave out the charcoal?" "What happens if you leave out the soda ash?" When I was older I began to answer these questions for myself. A waste of good material, my father said. I always suspected he was talking about me as well as the ore I used. I discovered that the inside of the crucible is blackened by the charcoal. But if you leave out the charcoal, the inside of the crucible is blue, not white, as if the malachite ore had been melted like wax. If you leave out both the charcoal and the soda ash, that is, if you simply heat malachite ore in a crucible, it turns black but does not melt. And soda ash alone melts right into the clay. It seemed to me that the soda ash made it easier to melt malachite, and melted malachite is a beautiful thing.
By 4000 BC I had learned to glaze quartz beads with a combination of soda ash and lime colored with malachite. At the same time I began applying the glaze ingredients to the surfaces of clay tiles, but because soda-lime glazes and clays shrink at different rates as they cool, they are not suitable for curved pottery. This limitation was overcome 2000 years later with the introduction of galena (lead sulfide), rather than soda ash, as the flux. From that point glass and glaze followed separate paths. Glaze developed as I wended my way down through generations of potters using lead in the form of galena and cerrusite (lead carbonate) to flux sand and clay. Glass emerged from the smelting tradition some 500 years later, with soda ash and potash used to flux lime and sand.
Having grown out of the metal arts, glass was cast in molds much as metals are. But beginning in about 30 BC glass began to be worked in its molten state, blown on the ends of iron pipes. Today glass is cast, blown, molded and drawn into almost any shape that can be conceived. Without it churches and skyscrapers would be pitch-black caverns, the color of fine wines would remain unappreciated in opaque clay bottles and cups. The microscope, telescope and electric light would be impossibilities. And the greatest contribution of all, that which has literally returned eyesight to billions, goes by the name, glasses. In short, had I seen slag as merely the refuse of the smelter, much of the world would have remained impenetrably opaque and many of its inhabitants hopelessly blind.
Notes
13.2.
Have you ever made ice cream from scratch? There is a fundamental problem in making ice cream; the freezing point of cream is lower than that of water and consequently ice is not sufficiently cold for freezing it. The solution is to add salt to the ice. Saltwater freezes at a lower temperature than pure water and the more salt is added, the lower is the freezing point. This is not peculiar to saltwater; any solution melts at a lower temperature than its solvent. We use salt because it is one of the least expensive substances that dissolves in water, but we could use many other materials to produce temperatures lower than the melting point of water. As a case in point, sugar, too, lowers the freezing point of water, which is the reason that ice cream, a solution of sugar in water with various suspended milk fats, has such a low freezing point to begin with.
Consider the sequence of events that take place when water freezes. We begin with pure water at room temperature, 25?C and cool it, say, by placing it into a freezer with the temperature set at -15?C. The temperature of the water falls, 24, 23, 22?C… A peculiar event occurs when the temperature reaches 0?C; a crystal of ice forms. Though we continue to cool the water, its temperature ceases to fall. An unobservant reader may have glossed over this remarkable statement and it bears repeating. We have water at 0?C in a freezer at -15?C, and yet the temperature of the water remains at 0?C. Though the temperature does not change, all is not static in our water sample; the ice crystal is growing. The water sample is now half ice, yet its temperature is still 0?C. It is now almost completely frozen, with only a single drop of liquid water remaining and yet the temperature has not budged. Only when the final drop has frozen does the temperature begin to drop, -1, -2, -3?C, until at last the ice reaches the ambient temperature of the