A coopered top might be the most some think of when it comes to curvature on a boarded chest. A little poking around discovers that square bodies with a curved top isn’t anything close to the end of the line, especially with the Cassone type of boarded chest. Specifically, the handful of Italian Chests that have a curved front are known as “Goffano,” according to Peter Thornton*.
The most well known of these (in the U.S.) is the Medici Chest.
A herculean level of research and conservation has been performed by the PMA in the study of this chest. Estimated to have been produced from 1450-1460 in Florence, this cassone is actually one of the simplest to design and construct of the type.
At right is a digital sketch for laying out the curves of the chest sides. The body of the chest is drafted from a square. Both arcs are 1/6th of a circle, where the radius equals the sides of the square. The first arc (left side of the square) is springs from the halfway point of the opposite plane (right side of the square). This means that the ends of the first arc terminate 1/6th of the width of the square on the horizontal planes. The second arc is centered halfway between the 90° corner on the lower right and the terminus of the first arc (1/6th from the left edge of the square). The radius of this arc is still equal to the height of the square, so it would be best to lay this out with two sets of dividers: one set for the height of the square, and one set to 1/2 of 5/6ths (or 5/12ths the module).
At left we have the same layout square without all the nauseating additional lines and marks. We’ve also added a little triangular bit to the bottom. See, the Medici Chest, like several of this class of boarded chests, has added feet nailed on to the bottom edge. The strip for this has a maximum width of 1/12th the height of the square, and tapers over the length (5/6ths of the square). Another little triangle bit extends past the 5/6ths point, making this an oblique scalene triangle. I couldn’t figure the math on this piece after a couple hours, so I eyeballed something that looks pretty nice.
In construction, we’ll then cut away along the entire top arc from side to side. The front arc is then cut from what remains (meaning we end up with a little more of the top arc remaining than the face arc). Once the foot is put on, the top arc should be about parallel to the ground, resulting in what is actually a hard to deconstruct but very easy to produce curve-faced boarded chest.
In the Medici, multiple boards are joined on edge to roughly match the arc of the face. The lid and back boards are also made up of multiple pieces, while the floor appears to be one solid piece. Cracks in the boards and in the joints between them have been “taped” over with hide glue bearing parchment. This chest also includes two battens to support the cooperage of the lid, in addition to the end pieces. All these parts are also based on a 1/6th chord of a circle.
Iron bands reinforce the joinery along the face of the chest and at the nailed “corners.” It is also wise to note the ironwork was applied after the piece was gessoed in two layers and painted. The layout of the banding must have been known, however, as the two bands that span the height of the face are centered 2/5ths from each end of the case.
Information about the locks (of which there are two keyholes evident on the face of the chest) and the hinges is unfortunately lacking. We can see the hinge mechanism isn’t visible from the inside, nor top, of the chest, contra-indicating strap hinges. Given the attachment and orientation of the lid, it is definitely not a pintle hinge either. This means the hinge was likely some kind of butterfly or box-type hinge mounted to the back and inside lid of the chest. If anyone has privately taken pictures of this piece and wouldn’t mind sharing, I’d certainly relish a look.
The coopered front and back boards are nailed to the end boards, in full accordance with our definition of a boarded chest. The lid is likewise nailed to the battens and rails. The floor, however, is somewhat of a mystery. There are no obvious indications of nails from the front edge, nor from the sides. This could be because the nails for the floor are covered by parchment, gesso and paint, or there could be a series of rabbets, stopped dadoes, or mortise and tennons. Again, the available documentation is lacking.
The final piece to talk about with this chest is the finishing. The paint is tempera based pigment applied over gesso. Interestingly, the coarse layer of “gesso” for this piece is calcium carbonate (marble dust/plaster). For whatever reason, the initial layering for this chest was prepared in the same method as a fresco, though with animal glue as a binder. The second layer is true gesso, finely ground gypsum (calcium sulfate) — proper Italian Gesso.
The pigments themselves are obviously naturally occurring, being the piece predates manufactured pigments by several hundred years. The paints are egg temper, rather than oil, casein, or size. Nothing remarkable there and more of interest to those interested in period painting techniques than this blog is typically aimed for.
Then there is, of course, my great complaint. This piece is listed as being made of “Poplar” which is mightily mis-informative. If I haven’t beaten this horse dead enough: this chest is made of a European Popple, not Tulip Poplar. Should the PMA ever get around to getting a taxonomic study of the wood, we’ll find out which species of the genus Populus this chest is actually made of. My bet is still on Populus Nigra.
I highly encourage everyone to check out the conservation page presented by the Philadelphia Museum of Art. Word of warning, there are several Flash movies on the related pages that do not appear to work on Google Chrome nor Firefox. Perhaps with more interest, the PMA might rework their website for the under-40 crowd on the internet.