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" - Done3 "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...
