Meddling with madder - part 2

 The results of the dilution test after 24 hours in the madder solution.

With the first experiment on colouring antler with madder done, the basic recipe was elucidated. The next step was to determine which strength of solution led to which red colour strength. To do this a set dilutions was made. So, to recapitulate, the basic recipe was:

• Pre-soaking antler for 1 hour in water
  
• Make madder solution with 4 gram sodium in 400 ml water (a 1% solution) + 5% WOF madder extract for 1 hour at 60 degrees Celsius
• Antler for 2 hours in madder solution at 60 degrees Celsius
• Cool down for 24 hours in madder solution
• Rinse with cold water

Dilution test

For the dilution test a set of five different solutions was made. The basic madder solution was diluted with a 60 degrees Celcius 1% sodium solution in 5 different glass jars:

• 100%  = 200 ml basic madder solution
• 50%  = 100 ml basic madder solution + 100 ml sodium solution
  
• 30%  = 60 ml basic madder solution + 140 ml sodium solution
  
• 20%  = 40 ml basic madder solution + 160 ml sodium solution
  
• 10%  = 20 ml basic madder solution + 180 ml sodium solution
  

The results of the dilution test directly after 2 hours at 60 degrees C. The (quarter) antler pieces are at the back, while the elongated bone pieces are at the front.

As I also had some (cow) bone pieces leftover from making soup, these were added as well to the test. The antler and bone responded differently to the dilution test. The bone produced a much lighter shade of red than the antler. This could be due to the fact that the bone was still 'fatty', and thus less able to absorb the madder. Or it might be that (cow) bone is less able to absorb the madder than antler. The 50% solution looked most agreeable to me, having a full red colour and not being too dark red. This solution was chosen for the production of the coloured tablemen.

Finalisation

The results of the actual colouring of the tablemen were not as straightforward as thought. The coloured antler game pieces had different shades of red, giving it a spotted appearance. Also, a wet solution brings out the fibres (just like wood), giving the game piece a slightly rough texture. Especially, the porous inside of the antler produces the most 'rough' texture and needs sanding to make it smooth again. The first game piece was sanded to much, and blank bits appeared. Therefore, I repeated the colouring procedure on the same game pieces in order to darken and recolour the light coloured spots. The result was that the game pieces were now a dark red colour.

 

 When you saw the test pieces in half you can see that the madder colour consists only of a small layer on the bone and antler. only on the porous part it invades further into the tissue.

 

 

The wet tablemen showing a spotty colouring.

When the tablemen were dry, the porous parts were carefully sanded with a 320 grid sanding paper, after which the complete gaming piece was polished with a cotton polishing wheel. Afterwards the piece was oiled with walnut oil, just as it was described in the 12th century treatise by Theophilus. 

 

The 100% and 50% madder solution test pieces with walnut oil.

 

 

Some of the madder coloured and uncoloured antler tablemen after the walnut oil finish.

Meddling with madder - part 1

I have been quite intrigued by the red coloured medieval tablemen that are found in the different museum collections around the world (for instance the Metropolitan Museum of Art, the Victoria and Albert Museum, the Museum für Angewandte Kunst Köln, among others). How were these pieces coloured and is this easy to reproduce? The how was easily answered, as the monk Theophilus provides a recipe in his book 'On divers arts' which was written around 1122 - a similar date as most of the red game pieces, which were manufactured in workshops in Cologne, Germany.

A game piece with Samson slaying the Philistines with the jawbone of an ass. Madder coloured walrus ivory. 6.3 by 1.3 cm. Made in Germany around 1140-1150. Photo Metropolitan Museum of Art, Cloisters, New York, NY, USA.

 

Theophilus writes in Chapter 94 of his book:

'There is also a plant called madder, whose root is long, thin, and reddish. After it is dug up, it is dried in the sun and pounded in a mortar with a ball. Then lye is poured over it and it is cooked in a raw pot. When it has boiled well, if the bone of an elephant or a fish or a stag is put in it, it will become red. from these bones or horns knops can also be made on the lathe for the staves of bishops and smaller knops for various useful objects. When you have turned these with sharp tools, smooth them with shavegrass. Collect the shavings on a linen cloth and, still turning the lathe, rub them vigourously on the knops which will then become completely shining. You can also polish horn-handles, huntsmen's horns, and [horn] windows in lanterns with sifted ashes on a woolen cloth. But do not forget to smear them finally with walnut oil.'

Of course the bone of an elephant is ivory, the bone of a fish relate to normal animal bone, and the bone of a stag is antler. I am unsure if Theophilus also means that (cow, goat) horns can be stained, as these have a quite different structure more similar to nails and hairs. However, wool for medieval clothing is commonly stained with madder. There is evidence that madder was already cultivated for this purpose in the Netherlands in the 12th century; in later centuries the Dutch madder became famous for its quality.

A similar uncoloured game piece with Hercules throwing Diomedes to his man-eating horses. Elephant ivory. Made in Cologne, Germany around 1150. Diameter 7 by 2 cm. Photo Metropolitan Museum of Art, Cloisters, New York, NY, USA.

As I was making a set of alquerque game pieces from antler, I wanted to make one set coloured red. The recipe of Theophilus was not very specific. In fact it looked more like a medieval cooking recipe without amounts. Searching on internet did show many recipes for colouring with madder, but these all concerned wool or cotton, and all are different as regards to amounts of the ingredients. 

 

A mordant - alum - is needed to fix the red colour to wool. The wool is first treated with the mordant, and then to the colouring solution. For cotton and hemp, both non-animal (plant) fabrics, an extra pretreatment is necessary before the alum. On the other hand Theophilus, as well as the early 18th century scientists do not mention alum at all for bone colouring. 

There are also other steps in the colouring process that need to be considered: temperature influences the colour; a temperature above 82 degrees Celcius turns the red colour into brown (for wool). Hard water (basic pH) increases the intensity of the red colour. The time in the colour solution and the strength of the colour solution influence the outcome as well: the longer, the darker, and more pigments in the solution also make the end result a darker red.

So what is the best way to colour antler madder red? I decided to do some tests to find out.

The first test

Madder powder as well as madder extract was bought from paint mill 'De Kat' in the Netherlands. Madder extract has already the red pigments (alizarin and purpurin) from the root extracted, and is sold as a plaque of dried crystals, which needs to be dissolved again. The madder powder is finely ground madder root, from which the madder pigments still need to be extracted before colouring the antler (or wool). I also purchased some alum from 'De Kat'.

As a basis I used 'the Maiwa guide to natural dyes - what they are and how to use them'. This free pdf guide (provided by the Maiwa company which also sells these pigments) provides a very clear description on colouring for each dye and as well as for mordanting. 

 

Left: The two basic madder preparations from powder and extract in the 60 degrees Celcius water bath. Right: the setup in the kitchen with the meat thermometer at 60 degrees.

 

The amount of dyestuff needed is based on a percentage of the weight of fibre (WOF), in my case the weight of the antler pieces. For madder powder this is 35-100% WOF, for madder extract this is 3-8% WOF. The antler pieces should be just fully immersed in the solution. So the actual amount of water does not matter, the amount of pigment that is available to the fibre does. I used 50% WOF for the powder and 4% WOF of extract.

Left: Pretreated antler pieces: with water in the glass, or with alum in the plastic box. Right: Four smaller test pots in the 60 degrees Celcius water bath.

 

Half of the antler test pieces were pretreated with alum, 15% WOF (as for wool). The other half was only immersed in water. During mordanting, the solution with the antler pieces was kept around 60 degrees Celcius for one hour. The pots with the solution were heated au-bain-marie (a waterbath) in a pan on a low flame and the temperature was kept in check using a digital meat-thermometer. If the temperature started to rise, a bit of cold water was added to the pan. After one hour, the pots were left to cool.

I made 400 ml of each madder solution. The pots with the madder solution were placed at 60 degrees Celcius for one hour in the waterbath, as described above. During the hour the colour of the powdered solution darkened, the extract solution was quickly dissolved and had a similar dark red colour.

 

Then the pretreated antler pieces were divided over smaller pots and the colouring solutions added. To the pots with antler pieces without alum an extra 2 gram of household sodium was added to each madder solution. The sodium carbonate was used to raise the pH of the solution to see if this influences the intensity of the colour. The test consisted of five pots:

• Antler mordanted with alum, madder powder solution, with sodium added during cool-down
  
• Antler mordanted with alum, madder powder solution, no sodium
• Antler mordanted with alum, madder extract solution, with sodium
• Antler with water, madder powder solution, no sodium
• Antler with water, madder extract solution, with sodium

The pots were kept around 60 degrees Celcius in a waterbath for 2 hours, after which they were left to cool down for 24 hours. Then the antler pieces were rinsed with cold water and dried.

Colour after 2 h 60 C degrees bath. The darker red coloured pieces on the right are without alum  pretreatment and with sodium.

The colour after 24 h cool down with the same oder of test pieces. The piece on the far left (powder + S + alum) was treated with sodium during the cool-down period and gained in colour strength.

As it turned out, mordanting with alum did have no positive effect on the colouring process for antler. Sodium, on the other hand, did. All antler pieces in a solution containing sodium were dark red, the one with sodium added later medium red, while those without were only lightly red coloured. Both the madder extract and the madder powder did colour equally well. Madder powder is cheaper than madder extract, but madder extract is a clearer solution and does not have the risk of the powder grains to become affixed to the antler. So the extract was used for further experimentation (in the next blogpost).

A side note

 

Science also had an early interest in colouring bones red. The first scientific study on the effects of madder on bones is from the early 18 century by M. Du Hamel du Monceau and published in the Philosophical Transactions of the Royal Society of London. An observation from a surgeon eating a pig with red bones, led to experiments where pure ground madder was (forcibly) fed to chickens, which died after a few days. Indeed, the chicken bones had become all red, but not the feathers.

 

 

Nowadays the synthetic red pigment (alizarin) that is also found in madder is still used to study the growth of bones and their calcium deposits.

Smooth newt (Triturus vulgaris) with bone coloured with alizarin. Bar = 5 mm.

Sources

• G.C.H. Derksen (2001) Red, redder, madder. Analysis and isolation of anthraquinones from madder roots (Rubia tinctorum). PhD thesis, Wageningen University, Wageningen the Netherlands. https://edepot.wur.nl/197629.
• M. Du Hamel du Monceau (1739) Observations and experiments with madder-root, which has the faculty of tinging the bones of living animals of a red colour, by M. Du Hamel du Monceau, F.R.S. & c. Communicated in a letter to Sir Hans Sloane, Bart. Pr. R.S. Translated from the French by T.S. M.D.F.R.S. The Royal Society of London Philosophical Transactions Vol. 41, pp. 390-406. https://www.jstor.org/stable/104301
• Antje Kluge-Pinsker  (1991) Schach und Trictrac. Zeugnisse mittelalterlicher Spielfreunde in salischer Zeit. Jan Thorbecke, Germany.
• Vivian B. Mann (1977) Romanesque ivory tablemen. PhD thesis, New York University, New York, USA.
• Theophilus (1122) On diverse arts. Translated by J.G. Hawthorne and C.S. Smith (1979) Dover Publishing, Garden City, NY, USA.
• The Maiwa guide to natural dyes - what they are and how to use them. https://naturaldyes.ca/instructions 

Who is afraid of red, yellow and blue?

Barnet Newman - Who is afraid of Red, Yellow and Blue III. Stedelijk Museum Amsterdam, the Netherlands.

A bit curious opening for a blog on medieval furniture, a contemporary artist that has attracted much attention with his paintings, especially those (including this one) that were violently attacked with knives by people who did not like the art style. But hopefully the image makes sense when reading the remainder of this post.

Around seven years ago I was helping our neighbours with the transport of a new sewing machine for (historic) shoemaking. At the place where we collected the machine, there stood a neglected Glastonbury type chair. When the owner heard that I made medieval furniture he donated me the chair. I did not like the chair. It was ugly, made from cheap spruce and had become mouldy from staying outside too long in rainy weather. But I thought perhaps I can upgrade the chair into a version that my neighbours will like. Then I discovered that this Glastonbury chair was wrongly constructed (see previous post). More work needed to be done.

It became a long term project, I only worked on it when the projects I liked were finished and I had nothing else on hand. First, the chair was cleaned with chlorine to remove the mould and the parts were dried for several months. Then, the construction was corrected by glueing an extra piece of wood on the outside of the backrest, so the were parallel again with the rest of the chair. There is no historical evidence for such a solution, but it works and is easier that reworking the seating and backrest. Then, to create a more comfortable chair, all sharp edges were rounded, either by using a router, spokeshave, draw-knife or scraper.

 Left: the extra piece of wood added to the backrest to enable a parallel armrest. Right: the trefoil decoration on the armrest.

Next, I carved a 'Gelderse' (Tudor) rose on the backrest, as this is the sign of the historic clothing company of my neighbours. Also I made some trefoil decorations on the armrest. In the end I had an upgraded, but still ugly spruce chair. Only one thing could hide that it was made from spruce: paint.

Left: The carved 'Gerderse' rose on the backrest, already covered in a layer of gesso. Right: The painted  rose.

The question then arises was medieval furniture painted, especially late medieval furniture. There is a lot of debate around this theme, but the answer is of course yes (see the blog of Johann International for example, the advocate of painted medieval furniture - for instance this and this post). A very large part of the medieval furniture was painted, but there are two causes why most is lost. First, time causes the decay of the decoration by use of the item itself as well as by changing environmental (moisture) conditions. Secondly, in the neogothic 19th century they found pure oak wood more to their liking. Thus, the furniture was stripped of their paint, though sometimes traces of it still can be found. The original Glastonbury chair has much decorative carving on the armrests that would have stand out better if it was painted. I do not know if this original indeed was painted, but the spruce one now is ... in Red, Yellow and Blue.

Who is afraid of a red, yellow and blue Glastonbury chair?

The broken down Glastonbury chair ready for transport to their new owners, 
the Gelderse Roos historical clothing company. 

Painting the pole lathe

Last weekend in the Historic Open Air Museum Eindhoven we started to decorate the large horizontal beam of our pole lathe (which bears the name of our guild) with medieval paint. We chose the colours of Nimweghen (black and red) for the letters and background, surrounded by a green "frame". Actually we only succeeded in painting the red and black parts, but the result is already great. We sure have an eyecatcher now.

Journeyman Bram is painting his pole lathe

Our egg tempera paint was made using the guidelines of Cennino DÁndrea Cennini in his 15th  century book Il libro dell' Arte. In short, egg yolk was rolled dry in the hands, the yolk sac opened with a sharp knife and the fresh yolks mixed with pigments which were ground with a bit of water to form a paste. Bone black was used as black and Venetian red for red, (Jeroen) 'Bosch' green for green pigment. All pigments were obtained from paint-mill 'de Kat'.

Nearly finished, the blank wood will later be painted green.