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Denzil Wraight - Italian Keyboard Instruments |
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Making Italian Roses Materials: Most 16th-century Italian roses (i.e. principally from Venice) were made of thin cypress (0.2-0.5 mm) reinforced on the underside with very thin parchment (0.1-0.2 mm). If the total thickness exceeds 0.3 mm it will be found that it is difficult to cut this material and I recommend a total thickness not exceeding 0.25 mm, as I have measured on a rose in the 1579 Baffo harpsichord, Musée de Musique, Paris. However, some roses (such as those in Dominicus Pisaurensis instruments) used a thickness of 0.5 mm and four layers in order to build up an impression of depth. It is tempting to try to start with knife-cut veneers as an alternative, but these lack the stiffness across the grain of thin (solid) wood. Unless one has special sanding facilities for achieving this thickness, it will be necessary to plane by hand and then scrape and sand cypress to achieve the requisite 0.2 mm. When sanding the wood to thickness it helps to lay it on a block of wood which has been faced with sandpaper. In this way the material is better prevented from sliding while it is being sanded. The reinforcing parchment is glued in the normal way with hide glue. Nevertheless one must expect several breakages when working with cypress veneer; in this respect vellum is much more forgiving and less time consuming to work with. There is a distinction between vellum and parchment (1). Parchment is a split skin, and therefore tends to be thinner than vellum. William Cowley may now be the only UK supplier of skins (2). Many old roses were probably made of sheep skins, which gives an even, light colour, but I have obtained a calf skin vellum with similar colouring from Carl Wildbrett (3). Goat skins I have seen are too variegated in colour to be suitable for roses. It is preferable to select material which is slightly thinner (e.g. about 0.2-0.3 mm) for the lowest layer (i.e. usually the third layer) in order that it can be punched cleanly. The top two layers may be slightly thicker (e.g. up to 0.5 mm) in order that the appearance of relief is created. If the vellum is too thin, or is parchment, then a poor sense of relief will be obtained. A vellum which is crisp and hard is preferable to one which is soft or has layers that tend to separate. The design: Some old cypress roses show signs of scribed construction lines. One can use an HB pencil for layout on vellum, but sharply pointed dividers not only show the place where the cut should come, they can also guide the blade to some extent (especially in cypress). Usually one has to discover the correct opening for the compasses and where they have to be set in an empirical reconstruction on paper before attempting the layout on parchment or cypress. It helps to develop your design on the material before you apply glue, as described below, since the glue always produces some curling in the material which makes it harder to handle. Glue: I have used a liquid hide glue (Croid, available in tubes), or, which is now more easily obtainable, Franklin's Liquid Hide glue. Normal warm hide glue, fish glue in sheets, or even kitchen gelatine can also be used in the way described below. The advantage of Liquid Hide glue is only one of time saving. The slight disadvantage of this type of glue, which remains liquid at room temperature, is that the glue is less strong and more hygroscopic than hide glue which has to be warmed. However, I have not experienced any problems with de-lamination of roses. Before applying glue to parchment I have rubbed the top surface with 0 grade wire wool to remove some of the waxy surface finish (whatever it is...) and lightly sanded the underside with 180 grit abrasive paper. Fine abrasives in plastic fleece-type material (e.g. 3M "Scotchbrite") are also suitable. The underside of the first layer of the rose should be sized with glue (I have used half strength glue, i.e. diluted with 50% water) before the pattern is cut out. It helps if the top surface of the second layer is sized with an even more diluted version (say 4:1 or 5:1 water:glue); if there is too much glue on the upper surface it will appear obviously shiny. Of course, the underside of the second layer also requires preparation with glue before it is cut out. Hold the material flat while the glue dries; this will reduce its tendency to curl on drying. This can be done by pinning the material to a block of wood. When the first layer has been cut, it suffices to dampen the glue on the underside with a wet rag or sponge and dampen the top of the second layer (even if it has been sized), then place the two layers in a press. I have found that expanded polystyrene is excellent for ensuring even pressure over the rose, but it is essential to use a barrier film (e.g. kitchen "cling film") to prevent the glue sticking to the polystyrene. It can be removed, but it is unnecessarily time consuming to pick off bits of polystyrene. The rose and polystrene can be cramped between blocks of wood; this technique works reliably. Polyethylene foam sheet, as supplied for packaging in 2mm or 3mm thicknesses, is also suitable and does not stick to the rose. It is quite impractical to spread glue on the delicate structure of the rose design after it has been cut, and the lack of glue beads bulging out of historical roses suggests to me that this technique must have be the one used by the old makers. Tools: Surgical scalpels are recommended. When I last examined the quality of blades available here in Germany, Swann Morton were the best. The no. 11 blades (in a no. 3 handle) used to have a slight hook to the end which was extremely useful for cutting roses. In recent supplies I have found that the factory no longer achieves this shape so I now recommend 10A. Although the blades are thin (0.4 mm) it will be found advantageous on no. 11 blades to grind the tip of the blade so that it is only about 0.25 mm thick; this helps prevent the blade acting as a wedge and splitting thin cypress and also makes it easier to cut through the material in one cut, which reduces the amount of work involved. This is unnecessary with 10A blades. Don't be mean with the blades and use only the sharpest ones; this may require a new blade for each layer. Forget about trying to sharpen them for rose cutting; unless you have special jigs and very fine grits you will not achieve the sharpness of a newly-ground blade. In cutting the rose one also needs to pay attention to the direction of cut and where the cut will end, in order that the blade does not stray into a part which should not be cut through. An elementary point is always to turn the work so as to be able to see the guiding line and not hide it behind the blade. It is also advantageous to cut some parts of a design before others in order that the layer is still strong enough to be handled. In cypress roses the top layer is particularly difficult; here it is desirable to leave as much "wood" in the rose as possible, cutting out sections but leaving them held in place by a few narrow (e.g. 1 mm) bridges until the last moment. Although the cypress rose is slightly reinforced with parchment, this should not lull you into any false sense of security: one must always pay attention to the grain and decide how the wood could split at any point along the cutting line. Hard, end-grain wood (box) is recommended as a support for punching holes. Beech or maple may be adequate, but box is better, especially on soft vellum. One can also cut the rose on a block of endgrain wood; here the hardness of box is not helpful. Plastic cutting sheets for kitchen use (c. 10mm thick) are also suitable for rose cutting. Green plastic cutting sheets (c.3mm thick) sold in larger sizes for cutting paper and card contain compunds which quickly blunt scalpel blades. In this respect the kitchen sheets are better. For some roses one also needs a small chisel-like cutter which can be ground from a 1 mm (or larger, as required) drill. Although a wood handle can be made for each such tool, a pin chuck also holds such a cutter securely and enables accurate work. All my small, used HSS drills land in the box containing my rose punches since I occasionally need to make a special hole or other shaped cutter. Marc Vogel now sells a range of small punches (2-30 mm diameter) (4). A x3 jeweller's eyepiece for close in work is useful but one is so close to the work that it is not the best solution. Binocular magnification at about x2.5 -x3 is better. One can buy ready made glasses which are fairly inexpensive in the range 0.5 to 2.5 diopters.
1. See The Calligrapher's Handbook, C.M. Lamb (Faber & Faber, London, 1956) ch. IV. My thanks to Barbara Shaw for a copy of this source! |