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Our fourteenth A&S Research Paper comes to us from Lady Angela Mori of the Barony of Bhakhail, who demonstrates and explains the process of making one of the splendid helm crests so familiar from manuscript illuminations of tournaments. (Prospective future contributors, please check out our original Call for Papers.)

Making a Leather Swan Helm Crest

A German heraldic crest for a tournament. Sold at auction by Pierre Bergé & Associés.

A German heraldic crest for a tournament. Sold at auction by Pierre Bergé & Associés.

How to Model Crests or Helmets: “Whenever you have occasion to make a crest or helmet for a tourney, or for rulers who have to march in state, you must first get some white leather which is not dressed except with myrtle or ciefalonia, stretch it, and draw your crest the way you want it made. And draw two of them, and sew them together; but leave it open enough on one side so that you can put sand into it; and press it with a little stick until it is all quite full. When you have done this, put it in the sun for several days. When it is quite dry, take the sand out of it . Then take some of the regular size for gessoing, and size it two or three times. Then take some gesso grosso ground with size, and mix in some beaten tow, and get it stiff, like a batter; and put on this gesso, and rough it in, giving it any shape of man, or beast, or bird, which you may have to make, getting it as like as you can. This done, take some gesso grosso ground with size, liquid and flowing, on a brush, and you lay it three or four times over this crest with a brush. Then, when it is quite dry, scrape it and smooth it down, just as you do when you work on panel. Then, in the same way, as I showed you how to gesso with gesso sotile on panel, in that same way gesso this crest. When it is dry, scrape it and smooth it down; and then if it is necessary to make the eyes of glass, put them in with the gesso for modeling; do modeling if it is called for. Then, if it is to be gold or silver, lay some bole, just as on panel; and follow the same method in every detail, and the same for the painting, varnishing it in the usual way”

– From Chapter CLXIX, Il Libro dell’Arte (The Craftsman’s Handbook), Cennino D’Andrea Cennini

Contents

The Process
Terms and Definitions
Bibliography

The following text is the description of the helm crest shown above. This piece was sold for 8000€; interestingly enough this is a fraction of what it would have cost at the time of making it.

“A German heraldic crest for a tournament Great helm, Zimier, in 14th-15th century style. Formed as a Swan’s head, accurately constructed of gesso and coarse fibre, probably jute, over a hardened sculpted leather core, the base hollowed for fitting the crown of the helmet skull, with pairs of lace-holes at the sides, painted white and heightened in grey, the base and the beak with traces of gilding over a red base coat, and in “aged ” condition throughout. Height 37 centimeters; weight: 1095 grams.”

This paper describes the steps I took in making the Swan Helm Crest based on Cennini’s text and the picture of the extant helm crest described above. I wanted to do my best at recreating this swan while staying true to the original materials and techniques used during the time it was made.

Materials for crest construction. Photo by Lady Angela Mori.

Materials for crest construction. Photo by Lady Angela Mori.

The Process

“you must first get some white leather which is not dressed except with myrtle or ciefalonia,”

The white leather is what we know of today as Vegetable Tanned Leather. Myrtle was one of the plants used to make this kind of leather. So far no one has been able to translate what “ciefalonia” is, though I’m sure it is a plant similar to myrtle. Vegetable tanned leather can be used in a process called Cuir Bouilli. This is a process in which the leather is wet with water (the water may or may not be hot), and then it is molded into a shape of sorts and then dried (sometimes with heat). It will keep its new shape quite well once dried.

“stretch it, and draw your crest the way you want it made. And draw two of them, and sew them together”

I would like to take a moment and state that in Cennini’s writings, he takes little time to really explain how to copy a shape and make it so that it will fit on a helm. Taking two pieces of material to get the shape down doesn’t work unless your piece is essentially very simple. And he does not include that the bottom really should have a shape sewn in that is similar to the shape of the helm. After making 3 helm crests I can most definitely say that a pattern would have been more complex than what he states above.

A line drawing of the design. Photo by Lady Angela Mori.

A line drawing of the design. Photo by Lady Angela Mori.

I made a line drawing of the original crest. I then went and cut this shape out of 2oz vegetable tanned leather. After looking at the shape I chose to modify the neck some because I was concerned that the curve I made would be too extreme and force the head to touch the chest. So I cut out some extra shapes and added them to the neck to prevent this. In hindsight I should have made a pattern first out of fabric or felt sheet to get the proper shape.

I then went ahead and used linen thread that I had spun and plied to sew the swan pieces together. I used a whip stitch to hold them together. I did this because it will have some give when shaping the leather with the wet sand. Leather stretches a good bit and would shift. A straight running stitch will not have as much give, preventing the leather from taking the shape that you are trying to give it.

“but leave it open enough on one side so that you can put sand into it; and press it with a little stick until it is all quite full. When you have done this, put it in the sun for several days. When it is quite dry, take the sand out of it.”

I wet the leather swan and packed sand into it, and let it sit in the sun. When it was dry I then removed the sand at the base of the swan.

The swan form filled with sand. Photo by Lady Angela Mori.

The swan form filled with sand. Photo by Lady Angela Mori.

“Then take some of the regular size for gessoing, and size it two or three times.”

I used rabbit hide glue for the sizing. To work with it, you must first soak the dried glue in water; I would say around 2 ½ parts water to the glue granules. Once the glue has softened, it must be carefully heated to liquify the glue. If it is heated to too high a temperature, it will break down and not hold together as a glue. I put hot water in a bowl and then placed another bowl containing some of the gelatin (glue) in the larger bowl. This will indirectly heat the glue to the right temperature and keep it liquid while you work. When the heat is removed the glue starts to turn back to a solid gelatin.

Left: rabbit hide glue after soaking. Right: rabbit hide glue being heated. Photo by Lady Angela Mori.

Left: rabbit hide glue after soaking. Right: rabbit hide glue being heated. Photo by Lady Angela Mori.

I applied the glue to all the pieces. This not only helps the gesso stick to the leather later on, but also helps in hardening the leather as well. The leather absorbs the glue into its fibers which helps give it strength not just on the surface, but on the inside structure as well. One must be careful when applying the glue to make sure that you only work on either the flesh or the grain side of the leather at a time —if the leather is soaked through all the way it will lose the shape that you just made and you will have to re-shape your pieces. I find that coating the grain side first works better because it absorbs less of the glue, but will give a good base structure for when the other side has glue applied to it. Make sure to let the first side completely dry before moving on to the next.

The crest completely covered in glue. Photo by Lady Angela Mori.

The crest completely covered in glue. Photo by Lady Angela Mori.

“Then take some gesso grosso ground with size, and mix in some beaten tow, and get it stiff, like a batter; and put on this gesso, and rough it in, giving it any shape of man, or beast, or bird, which you may have to make, getting it as like as you can. This done, take some gesso grosso ground with size, liquid and flowing, on a brush, and you lay it three or four times over this crest with a brush. Then, when it is quite dry, scrape it and smooth it down, just as you do when you work on panel.”

The next step was to make the gesso grosso with size and add beaten tow.

Review note – Prior to making this helm I had made another one using a premixed “Italian Gesso” from Natural Pigments. This pre-mixed gesso consisted of calcium sulfate dihydrate and dry rabbit hide glue. When reading the directions on mixing the gesso grosso ground with size I thought this was the equivalent. When making it I had noted that it was a bit undesirable due to the inconsistency of the ratio of glue to calcium and this made it hard to get the right amount of water in the mixture without it being too soggy or too dry. I had made the decision that I would later on mix them differently. I chose to prepare the glue to its liquid state before adding the calcium.

To make the gesso mixture I heated up some of the rabbit hide glue as done before when sizing the leather. I then added calcium sulfate dihydrate and mixed it in, using my fingers to try and break down any lumps of the Calcium. I kept adding the Calcium until the consistency was like a thick cake batter. I then slowly added tow into the mixture making sure it was thoroughly coated with the liquid gesso. Once the mixture started to become a lumpy but still gooey mixture I started applying it to the leather. Sometimes I used my hands and sometimes I used a brush to apply it. The cooler it became the more thick and less flowing it would become. If I needed the mixture to be flowing I just put the bowl back into the hot water bath to warm up the glue. After it dried I then scraped the high points down some with a knife.

Left: crest after gessoing. Right: closeup of gessoed surface. Photos by Angela Mori.

Left: crest after gessoing. Right: closeup of gessoed surface. Photos by Angela Mori.

Review note – At this point I had gone only by the comments made by D. Thompson jr. in his translation of ‘Il Libro del Arté’. I recently read an article “Questions about Medieval Gesso Grounds” by Beate Federspiel, where the author had gone through and done further research to show that “examination of grounds in Italian paintings by the Laboratoire de Recherches des Musees de France elaborates on the double structure of the Italian gesso grounds. This double structure was also shown in the examinations by the National Gallery’s laboratories in London.” (Federspiel, 62.) Which means that they did a chemical analysis, finding that the base layers of paintings that also had gesso grosso as the base layers consisted of calcium sulfate anihydrate mixture with calcium sulfate dihydrate. In layman’s terms, the plaster of Paris used was actually made of calcium sulfate anihydrate (which absorbs water less than the modern day plaster of Paris, calcium sulfate hemihydrate) and some dihydrate as well. The author stated that perhaps the full chemical change did not happen because the only water to be absorbed was through the gelatin of the animal hide glue. I have done testing and found that the water content in the glue had no effect on the chemical reaction of the calcium sulfate anihydrate when mixed with it. If anything it acted very much like that of adding the calcium sulfate dihydrate to the warmed glue that I had done with my work previously. I took some of the gelatin and ground it down with the calcium sulfate hemihydrate and then heated it. It reacted the same way with no heat (I have found to be indicative of water absorption and chemical reaction for plaster of Paris) like that of the dihydrate. So I must conclude that the reason for using this as a base layer must be to help in the prevention of moisture damage to the piece being made. Further testing will help me in analyzing the reason for this procedure and choice done by the artists of the Middle Ages.

“Then, in the same way, as I showed you how to gesso with gesso sotile on panel, in that same way gesso this crest. When it is dry, scrape it and smooth it down; and then if it is necessary to make the eyes of glass, put them in with the gesso for modeling; do modeling if it is called for.”

I then made a mixture of the glue and the calcium sulfate dihydrate but this time taking care to sift out any small hard pieces from the powder before adding it to the glue. I kept adding it until it became like a runny pancake batter. Then I applied it to the crest with a brush letting it pool in the recessed areas left by the first layers of gesso. When it was dry I scraped and sanded down the high points again and reapplied another coat until most of the shallows were filled. I also went ahead and added lids to the eyes. I also gessoed in a tongue that I had previously cut and gessoed. I used the gesso as a glue to set into the inside of the mouth. After everything dried I then went back over everything with my knife to scrape down any rough surfaces. I then went over the surface with a damp cloth to smooth out the gesso and take off any dust and shavings that may have been left on the surface.

Left: crest being scraped with a knife. Right: a closeup of the scraped surface. Photos by Lady Angela Mori.

Left: crest being scraped with a knife. Right: a closeup of the scraped surface. Photos by Lady Angela Mori.

“Then, if it is to be gold or silver, lay some bole, just as on panel; and follow the same method in every detail, and the same for the painting, varnishing it in the usual way”

I also went ahead and burnished down the beak, eyes and base. The beak and scalloped base were gilded on the extant swan so I went ahead to prepare the surfaces on mine for the bole.

Applying bole to the beak. Photo by Lady Angela Mori.

Applying bole to the beak. Photo by Lady Angela Mori.

I took some dried bole and ground it down and added a little water to make it into a smooth paste. I then took some glair and mixed it with the bole. I painted on numerous layers of the bole, waiting for it to dry between coats. I burnished the bole to make sure the surface as smooth.

Bole on the beak after burnishing. Photo by Lady Angela Mori.

Bole on the beak after burnishing. Photo by Lady Angela Mori.

I took some glair and honey and mixed it with water to make a fixative for the gold leaf. I brushed it on where I wanted the gold leaf to be applied, only going along in small areas. Each time I would apply a piece of gold leaf to the prepared area. When this dried sufficiently, I then went ahead and burnished it. I ran out of gold leaf while working on the beak. When I got more I went over the beak again with the size and the new leaf, because it was a different in color. When it was sufficiently dry I went ahead and burnished the gold.

Painting the swan crest. Photo by Lady Angela Mori.

Painting the swan crest. Photo by Lady Angela Mori.

I worked on the base area of the crest with imitation gold leaf using the same technique as for the real gold leaf. I plan on redoing the base in real gold later on because I am not happy with the results and it strays somewhat from what I have been trying to achieve, which is a crest made as close to original medieval techniques and materials as I can achieve. With that said, I will also state that gold was a very expensive metal and there are many writings that discuss ways to make metals that are not gold, have the look of gold. So to use a imitation gold leaf is not really straying from recipes and techniques used during the Middle Ages.

The finished crest atop the helm! Photo by Lady Angela Mori.

The finished crest atop the helm! Photo by Lady Angela Mori.

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Terms and Definitions

Animal Hide Glue – a size (primer) and hardening agent as well as a binder for gesso. It is made by soaking small pieces of rawhide in water and then boiling it for a long time to break down the collagen. When it is finished it is dried and crushed in to a granular form. Later it is used by taking some of the dried glue and soaking it in water. When it has absorbed the water it is then heated indirectly with a double boiler until it liquifies. At this point is it ready to be used as is or as a base for mixing other materials into it.

Bole – a fine red clay, commonly termed “Armenian bole” during the middle ages because of its origin, used as an underlay for water gilding because of its “waxy” character allowing the artist to burnish it to a smooth finish which is what was wanted for the surfaces that were to be gilded.

Cuir Bouilli – the shaping and moulding of Vegetable tanned leather. Vegetable tanned leather is leather that has been tanned with tannins used from plants. Some main plants used are Oak Gall, Myrtle and even black tea leaves. These tannins give the leather a property where the leather can be wetted and then molded into a shape and then dried with or without the aid of heat. When the leather is dry it will retain its new shape.

Flax– A plant that is harvested and used to make thread, which is woven into cloth.

Gesso

  • Calcium sulfate hemihydrate, Gypsum (also known as plaster of Paris). Made by heating calcium sulfate at 128 deg celsius allowing most of the water content to evaporate.
  • Calcium sulfate anihydrate – similar to plaster of Paris, but absorbs water less readily. It is made when calcium sulfate is heated in a kiln between 163 deg. celsius and 300 deg. celsius it becomes calcium sulfate anihydrate.
  • Calcium sulfate dihydrate – made from Gypsum. If the plaster of Paris is slaked, soaked for a long time in water, instead of air drying it becomes calcium sulfate dihydrate.

Gesso grosso – calcium sulfate anihydrate (see above)

Gesso soltile – calcium sulfate dihydrate (see above)

Glair – a sizing made from egg white.

Linen – the thread and cloth made from Flax. Linen thread was used to stitch the leather together to make the helm crest.

Tow – the left over scraggly shorter bits of material that is removed from the Flax before it is spun into Linen. Tow was added to the base layer gesso to help give it strength and give it bulk.

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Bibliography

Cennino D’ Andrea Cennini. The Craftsman’s Handbook: The Italian “Il Libro dell’ Arte.” Thompson, Daniel V., trans. New York: Dover Publications 1960, c1954.

Federspiel, Beate. “Questions about Medieval Gesso Grounds.” In Historical Painting Techniques, Materials, and Studio Practice: Preprints of a Symposium, University of Leiden, the Netherlands, 26–29 June 1995, edited by Arie Wallert, Erma Hermens, and Marja Peek, 58-64. Los Angeles: Getty Conservation Institute, 1995.

Waterer, J.W. Leather and the Warrior. Northampton, England: The Museum of Leathercraft, 1981.

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