Leather Helm Crest: Part 12 Applying Gesso grosso

Here is what Cennini suggests you do to apply gesso to the leather structure.

1. size it two or three times
Done.

2. mix gesso grosso and lay it on in a thick paste, modelling it to the animal shape needed.
Done.

3."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."
When I had moulded the gesso grosso paste onto the leather, I then mixed water with the remaining paste in the bowl and painted it over the damp gesso. It smoothed out the rougher lumps and filled any splits that had formed while the leather flexed. I was not going for a smooth finish, as I wanted to replicate a scruffy, hairy surface.

4. "Then, when it is quite dry, scrape it and smooth it down, just as you do when you work on panel."
I used some sculpture tools to remove any lumps and smooth the surface a little.

5. "Then, in the same way, as I showed you how to gesso with gesso sottile on panel, in that same way gesso this crest. When it is dry, scrape it and smooth it down;"
I applied a layer of gesso sottile with a brush, but made it pancake batter thickness. I think this is much thicker than was intended. Again, I did this so the plaster would 'catch' as it dried and pull into a textured surface to give more of a look like a wavy, bumpy coat of fur.

To make a smooth item, I would mix new gesso grosso immediately after adding the rough layer, making this second, smaller lot with less dry ingredients in the water. I would apply a thin coat with a brush, let it dry, mix a new batch, apply it etc., until there were three or four layers. I would use a rough cloth to rub down the damp gesso grosso where needed. I would also make my layer of gesso sottile much more aqueous and spend time 'polishing' the dry surface with a cloth on a chock.

http://www.noteaccess.com/Texts/Cennini/index.htm

Leather Helm Crest: Part 11 Applying Gesso grosso

The leather crest has been sized twice and has dried with a smooth, shiny surface. To make gesso grosso I used equal parts water and plaster. Put the water in a bowl. Mix 1/8th volume of powdered hide glue and 1/4 volume tow into the dry plaster. Then pour the whole lot into the water.

 

Mix the gesso together until it is like firm cream - spreadable but doesn't run. I had to add more plaster than the packet recommends so be ready to adjust until the mixture is the right consistency.

The gesso was applied in lumps with a spoon, at first, and then smoothed more evenly. Work quickly, as it will only spread for a few minutes before starting to catch as it sets.

Pay extra attention to the seams. It is important to make a thick enough layer of gesso over the seams, because it is easy to scrape too thin over a seam while smoothing out.

After smoothing out the gesso, the plaster has probably dried enough to start smoothing and moulding with your hand or a sculpting tool.

Check that there is an even thickness right around. Also check that the base of the crest is still the correct shape to fit on the top of your helm. When my gesso grosso dried, I found that the leather had changed shape and no longer fitted on the helm. While breaking of some plaster off (later in the day) to re-set the base shape, I found that the gesso was a much better thickness on one side than the other. I recommend trying to make the gesso grosso between 5 and 10 mm thick. The top piece is too thin

About 10 minutes after mixing the plaster, it became quite firm. I poured a very small amount of water into the mixing bowl and made some paste, like peanut butter in stiffness. I used this to fill in some low patches, especially around the eyes, so there was enough plaster to sculpt eyelids out of.

The crest stood to dry for a day and then will be covered with gesso sottile.

Leather Helm Crest: Part 10 "...size it..."

After rehydrating the hide glue, it was left for a day. This is how I prepared the crest for gesso by sizing it (painting it with size/glue).

I took the lid off the jar of size and added hot water from the kettle to a pot. I tried to get you a nice pic of the set up but the camera fogged up so my kitchen looks like a 70s family photo. I had intended to bring the water temperature up on the stove but the left over water in the kettle, after pouring enough for a cup of tea, was enough heat to melt the hide glue. The open jar was sat on a small ceramic plate, to act as a trivet and keep direct heat from the base, if the water needed to be heated on the stove.

After 5 minutes or so, the glue had melted.

The leather crest had the dried sand removed from the inside, but each time I moved it there seemed to be more. I will really have to give it another solid shake and brush before the final coat of paint or the sand will find a way to get on the paint and make it look grainy.

 I applied one coat of size and left it to dry for an hour. When I returned, it was touch dry with a gel-like texture. You can see, in the jar, how much size it took for a single coat coverage. If around a 1/3 was used in a coat, and the whole volume took 3 teaspoons of dried hide glue, it took around 1 teaspoon for the first coat.

After an hour the size had reset. This time, placed the open jar of size back in the water bath and turned the stove on to the lowest setting. After a few minutes the glue had started to melt. After 5 minutes, the trivet started to bounce around and the glue began to smell. At this point, it had become a golden honey colour and texture. The glass bottle was still not very hot, as I could pick it up with bare hands.

I applied a second coat of size, making sure to brush in a different direction. You can see the brush strokes at 90 degrees to each other on the snout. Leave the size to dry and then you can cover it in gesso grosso.

Leather Helm Crest: Part 9 A bowl of tow

I have prepared a bowl of tow to mix into gesso grosso. The rope I used was jute, with a synthetic strand bundle (the dark green bundle of fibres). First, I cut the rope into lengths of around 10cm and then unwound it to remove the synthetic bundle.

 

I tried cutting the fibres with a knife but found snipping it with shears much easier. I cut the fibres into pieces between 2mm and 10mm long. It took a couple of hours to get this half bowlful.

Leather Helm Crest: Part 8 Tow

In returning to an old question I had asked about tow, Cennini has the following to say on preparing gesso grosso:

'CLXIX How to Model Crests or Helmets.[211]
(after making the leather base)... 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.

1.    "...regular size for gessoing..."   As discussed in an earlier post, rabbit hide glue was not listed as the most common in use during this time period. It is, however, the most readily available form now. I will use it for this project and investigate other alternatives for future projects, to compare results.

2.    "...size it two or three times..." This could mean 'apply hide glue size to the outside of the leather base in two or three coats.' We often apply a coat of glue as a sealer to woodwork or leatherwork projects, to give better coverage of outer coats of paint. This may help to attach the plaster layer.

3.   "...Then take some gesso grosso ground with size..." We are going to use commercially available Plaster of Paris for our gesso grosso base. Since our plaster comes pre-ground in powdered form, rather than in blocks like Cennini had to deal with, we can go right ahead and mix in some powdered hide glue. He does not provide quantities or ratios. The text only implies that the size proportion is smaller than the plaster proportion.

4.   "...and mix in some beaten tow..."   I have found a few relevant descriptions for tow.

The Free Dictionary website says 

"n. Coarse broken flax or hemp fiber prepared for spinning.... ...[Middle English, possibly from Old English tow-, spinning (in tow-cræft, spinning craft, spinning)."

Word Reference.com says 

"tow /təʊ/    N

1. the fibres of hemp, flax, jute, etc, in the scutched state
2. synthetic fibres preparatory to spinning

Etymology: Old English tōw; related to Old Saxon tou, Old Norse tō tuft of wool, Dutch touwen to spin"

Dictionary.com says

"tow

2  [toh]  noun

1.

the fiber of flax, hemp, or jute prepared for spinning by scutching.

2.

the shorter, less desirable flax fibers separated from line fibers in hackling...

...Origin:  1300-1350; Middle English; 

Old English tōw-  (in tōwlīc  pertaining to thread, tōwhūs  spinning house); 

akin to Old Norse tō  wool

tow

3  [toh] noun Scot.

a rope.

Origin: 1425-1475; Late English (Scots);

Old English toh-  (in tohlīne  towline); cognate with Old Norse tog towline."

This suggests that if I take some rope made from the most common material of 1440, being either flax, hemp or jute, and cut very small fibres up to mix into the plaster, I can use this to "...mix in some beaten tow..." I suppose it would be possible to use unspun flax or jute from another source, too.

This method is supported by the composition of an extant bird crest. This bird is listed as being "...constructed of gesso and coarse fibre, probably jute, over a hardened sculpted leather core..." 
http://www.invaluable.com/auction-lot/cimier-heraldique-pour-grand-heaume-de-tournoi,-40-c-ee0776023c

So, I shall mix some finely chopped jute rope and powdered hide glue into some Plaster of Paris to make gesso grosso, and then paint the thick paste on to the leather form. It finally makes sense!

Leather Helm Crest: Part 7 Mixed hide glue

In preparation for applying gesso sottile over a layer of gesso grosso, I have mixed up some hide glue.

Put 1 part powdered hide glue and 2 parts water into a jar. The picture below shows the water and powder mixed on the left, sitting next to a jar of dry hide glue powder on the right

 

Let it soak for an hour, to take up the water. 

It becomes much thicker and more rigid, on soaking up the water.

To use this glue, it is recommended that you stir the granules and leave them overnight. Then, you can warm the glue up to a liquid state, using a glue pot or gentle heat in a double boiler. In a sealed jar, this glue can last a couple of weeks, at least. It is water soluble and can be reheated to return it to a liquid state, even when on a project.  

 This is what the rehydrated glue looks like, before being heated to a liquid state. The volume shown is 3 teaspoons of dry size and 6 teaspoons of water. It is the same volume in the picture to the left and the jar on the left in the image above. The expanded size has been stirred and chopped up with the plastic knife shown on the left, making it fluffier. Hence, it appears larger. 

This will be heated and painted on to the leather crest shape in 2 - 3 layers before the gesso layers are added.

Hide glue how-to

http://www.stewmac.com/shop/Glues,_adhesives/Wood_glue/Behlen_Ground_Hide_Glue.html?tab=Video

Here is a video showing how to make up hide glue. It follows a process I have seen in a few other places. You can also buy hide glue from the online shop. Luthier suppliers are a good place to get hide glue, which comes in amber coloured flakes.

Paint colours according to Cenninni

I am getting towards the painting stage of my first helm crest so it is time to start thinking about pigments. I have some ready ground pigments to mix into tempera paints and other forms of decoration, but want to check out what Cenninni has to say on the subject.

There is a long list of colours that Cennini instructs his readers to mix and use in specific styles of images. I like reading about the words he uses to describe different colour beards - ruddy, russet, black.

"Chapter XXXVI 

Know that there are seven natural colors[23], or rather, four actually mineral in character, namely, black, red, yellow, and green; three are natural colors, but need to be helped artificially, as lime white, blues--ultramarine, azurite[24]--giallorino"

He lists violet, blue, green, purple, 'ocher', ash grey, greenish grey, red and black made from a combination of lac, ultramarine blue, orpiment, pink, flesh colour, vermilion, red lead, white lead, verdigris, indigo, hematite, lime white, terre-verte, charcoal, malachite, turnsole, black, giallorino, cinabrese, sinoper, ocher, and azurite mixed with lye, water, egg yolks, egg whites, gum or size.

"This Shows you the Natural Colors, and How you Should Grind Black. 

Chapter XXXVI "

To find out the Cenninni's recommended method for mixing black relies on the purpose. He says to mix it on a hard flat stone using another, rounded stone. Amusingly, Cenninni says that if you were to grind it for a year, it would only improve the depth of the colour - I have an image in mind of a team of apprentices working around the clock, trying to beat the boredom. Once ground, it is to be stored in a pot of water with a dust cover over the top. He talks of using burnt peach stones, vine twigs and almond shells, as well as a black stone.

I will need a decent volume of both white and black paint for the badger crest. Hopefully the weather will stay good so I can work on it some more tomorrow.

Clothing for 1420-1482: A veil style

1. This method uses two large square veils. Place the first veil on your forehead, just below the hairline.

2. Wrap and pin the veil in place.

3. Roll/fold up the tail of the under veil, to help create bulk at the back of the head.

 

4. Pin this roll up so it is clear of the neck.

5. Centre the second veil so it is slightly further up the forehead than the first.

6. Use a large pin to secure the two sides of the veil at the nape of the neck. Make sure the head of the pin faces down and the point angles slightly away from the head. Make sure this is tight.

7. Find the centre line of the second veil, a few inches up from the hanging hem.

8. Pin this above the forehead.

9. Use more pins to arrange the veil into a whole range of rumples and bumps, as seen in various illustrations from 1450, especially those of Rogier van der Weyden.

Leather helm crest: Part 6 Preparing gesso sottile

About a week ago, I started to saturate some plaster of Paris to make gesso sottile. This is the second layer of gesso that Cennino Cennini recommends for the outside of a helm crest. In an earlier post I explored the chemical composition of gesso. Gesso sottile is a super hydrated version of plain plaster of Paris. By soaking the plaster, you are allowing it to take on more H2O (water), giving it the desirable property of a slower drying time. This means we will be able to add the final sculpting touches with more care.

Since this is the first time I have used plaster in this way, to sculpt rather than to make moulded objects, it is all a learning experience. I have no idea how well the plaster will stick to the leather, or how well the second layer of plaster will stick to the first, or how the paint will need to be applied. It will also be the first time I have made pigment based medieval paints. There will have to be some test pieces very soon...

Cennini suggests leaving your plaster to soak for 30 days, changing the water to ensure it remains clean. Other sources say this method is inexact - but it is the best evidence I have, closest to my chosen time period, so I have tried this method first. We can always try something else.

To make gesso sottile, I fill a bucket with water and poured plaster in. It is always recommended that you add plaster to water, not water to plaster. When making a gravy or sauce, this produces lumps but for plaster it works well. I mixed it gently and continued to add plaster until it was not absorbed immediately. I covered the bucket with another tub to stop rain, cats, frogs and leaves getting in. Now, we wait.

Leather helm crest: Part 5 Cennini's sand

To attempt Cennini's leather forming method, I have filled the stitched leather structure with wet sand.

In the section marked 'CLXIX How to Model Crests or Helmets.[211]'
Cennini suggests that after drawing up your model design...
"And draw [p. 108] 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 ."

Steps
1  "draw two of them" - I have used more than 2 pattern pieces to form a 3D shape. It is possible that Cennini intends that only very simplistic forms are made from the leather with all protuberances, such as ears, chins, arms and legs, being formed from the gesso grosso layer. I chose to go with the second interpretation, which forms more of the final shape from multiple leather pieces, since this design would add a considerable weight of plaster/gesso for final shaping, otherwise. I guess this just means I have more alternatives to try on future crests.





2  "sew them together" - Done







3  "but leave it open enough on one side so that you can put sand into it" - If I were making a full animal to stand on top of a helm, Cennini's method would help make a  fully formed body shape. Since I am using a head as the base structure, it was possible to have a large opening at the base of the neck to fill with sand. I plan to form a leather cap on the crown of the helm, and stitch this to the lower edge of the neck. As I did not want this leather cap to deform from the wet sand or pushing with a stick, I chose to add it after the main structure is dry.

4  "you can put sand into it; and press it with a little stick until it is all quite full"  - Done. I could have used beach sand, but did not want to have to rinse the salt and impurities from it, and some beaches locally are protected by State and National Park. Further more, while recently living in a coastal town, I worked alongside and became good friends with some women who were Indigenous Australians - they have taught me that it is important to seek permission from the local custodians of the land before removing anything, including sand. Buying sand was a compromise because I could not gain permission to take from local beaches, and this at least gave me the possibility that the sand may have come from somewhere with permission. Yes, I am an optimist.

You can see the colour difference from the left image, with the dry leather, to the right image, which is now packed with wet sand. It took a bit of shaping to get the top to sit in an oval. Next time I would make a wooden disc to fit inside the top to hold the shape.


5
"put it in the sun for several days" - Done. I am not sure it will stay seated where I have put it to rest, so I may need to find a way to chock it up without putting pressure on the outside and changing the shape.

6
"When it is quite dry, take the sand out of it ." - Waiting, waiting...

Leather helm crest: Part 3 leather pattern

After making the clay badger model for the crest, I let it dry for a day. On the second day the leather was firm enough for me to use some wood carving tools to finish the detailing and clean up the model. It would have been possible to cover the wet clay in a plastic bag and keep it moist for up to a week, but it wasn't necessary this time.

Before cutting up leather to make the crest structure, I will make a pattern. I chose to use felt, as it has only slight give and is easy to stitch.

I began by cutting a few pieces into manageable sizes with overlaps of at least an inch. The overlaps were trimmed down as I joined the pieces, so the excess fabric did not affect the pattern's ability to wrap. You can see the threads I used to tie the basic pieces onto the body first. I started to stitch from the nose back, using fairly long stitches in a contrast colour thread.

  

The ears were freed by cutting a split in the head pieces. These holes will be unnecessary in the leather model, as I plan to attach the ears to the outside of the head using separate pieces. 

Once the rough cover was pulled together, I trimmed the seams further and went back to tighten up any loose or puckering areas. 

Once all of the pieces fitted reasonably well, it was time to open the pattern pieces out. I wanted the finished item to be around the same size as the clay model. Since the felt pattern was made over the clay model, it was bigger than needed, and since plaster / gesso would be layered over the finished leather structure, the pattern pieces needed to create a smaller item than the felt cover. This was achieved by cutting on the stitch seams and not adding a seam allowance back in. 

The black lines are placement markers to help put the pieces back together. I numbered the pieces and transferred the felt pattern onto heavy card. Each piece was labelled and is stored in a bag. To keep my patterns neat, I like to mark them with-

* The item name

* The owner's name

* The date of creation

* If there is a seam allowance (SA) or not. If so, how much on each side, as certain sides of a garment often get different SAs.

* Number of pieces

* Description of the pieces (CF= centre front etc)

* Any placement marks

* Indicate any folds ( v--------------v)

I was planning to sew the leather with butted joins, so no seam allowance would be needed. I was only looking to make a rough structure from leather, with all of the texture done in gesso grosso and all of the surface detail completed in gesso sotile.

 In order to create a slightly smaller leather item, not exactly the same size, the pieces were trimmed a few millimetres in from the pattern pieces on the leather. I have chosen to try a piece of leather that is 2 - 3mm thick (slightly more pliable than belt leather). The pattern was inked on, as it should be covered by the gesso. The leather was also chosen because it is marked, making it less useful for other projects. I am hoping the water hardening and plaster layers will firm it up. I considered doing some tests but since structural integrity cannot be simply scaled up, doing tests on smaller pieces would not be truly indicative of the finished strength, and full size tests would be very costly. I still hope to do some striking tests with the plaster layer, at a later date.

The holes were marked with a rotary tool and every second spot was pierced with an awl. I will stitch through these holes. Again, it is not necessary to make a perfectly neatly stitched item, as all stitching will be covered in plaster. On future items, I would love to refine the process and do fine work at every level. Spacing the stitches out serves another purpose - since the stitching is tensioned and retensioned as each new piece is attached, the looser, longer stitches are more suited to tacking. In fact, short, neat, overlapped seams or saddle stitching would make the assembly process harder. 

Starting with the larger pieces, I lined up some of the placement marks and began to sew. The curved needle is helping to secure pieces at the placement marks until I stitch up to that point. Because there are very few corners and straight lines, it is a bit tricky to know how far to curve and sew each piece to the next. For this reason, I had 3 - 4 needles on the go.

First, I joined the front and the pieces from one side. Then I attached the nose and worked back from there.

Once the body was attached right around (in a box), closed as much as possible of the head. At this point, I was working with a hand reaching either through the head or through the base for most stitches. I attached the ears separately and closed the head.

The ears were trimmed to look less like a teddy bear and the sewing was complete on the basic leather structure.The next step will be to stuff them with wet sand and wait until it all dries.