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Beautiful Boulle Work

A masterpiece of inlaid intricacy begins with a sandwich of brass, sheet, wood veneer and waxed paper.

By Silas Kopf


“Plus c’a change, plus c’est la même chose.” This centuries-old French expression translates something like this: “The more things change, the more they stay the same.” It’s a bit of wisdom that seems appropriate for woodworkers. Though technological advances can change our tools and methods of work, we often work to standards that artisans established hundreds of years ago.

The marquetry and inlay work I do today is inspired by and measured against the skill and creativity of woodworkers who have practiced the craft for 500 years. Most notable among these artisans was André- Charles Boulle, whose last name is often used to describe the inlay technique that I used on the commodes shown here. During his lifetime (1642 - 1732), Boulle supplied French royalty with furniture that was incredibly rich in surface ornamentation.

Boulle’s inlay materials included tortoiseshell, brass, pewter and even animal horn. For contrasting woods, he often used rosewood, ebony, kingwood, and other dense, dark-toned tropical species. Boulle’s marquetry technique was to make two contrasting sheets of intricate inlay that were cut from a single sandwich of materials. If the sandwich, or packet, contained two layers that were light and dark, the two final products would be a sheet with a light pattern on a dark background, and a reversed sheet, with a dark pattern on a light background. One sheet would have been considered the primary pattern, in French the première partie. The opposite pattern was called the counterpart, or contrapartie. By sawing both patterns out of one packet and reassembling them on two trays, the background of the première partie becomes the motif of the contrapartie. Boulle made cabinets with both patterns in a single piece, or pairs of contrasting cabinets.

 

Preparing the packet

I have developed a way to do Boulle marquetry with modern tools and materials. This Boulle project uses two materials: sheet brass and dark bog oak veneer. They are assembled into a packet (Fig. A) with a sheet of waxed paper, backing layers of thick veneer, and the pattern.

I use standard brass that is .032-in. thick and veneer that I saw myself and sand down to exactly the thickness I need. This veneer should be slightly thicker than the brass, to make the final cleanup easier (Photo 9). It’s a lot easier to sand down wood to make it flush with the brass than vice versa. For this leveling process I have found that the veneer I make on the bandsaw holds up better than regular sliced veneer because the wood fibers haven’t been crushed. Even so, I glue a piece of newsprint to one side of the veneer with hide glue to strengthen the veneer when I cut the packet on the jigsaw. The brass is scuffed with a piece of fine hacksaw blade on the side that will be glued down to the cabinet. I use 1/16-in. thick poplar veneer for the two outermost veneer pieces, which are sacrificial—they only serve to stiffen the packet. The wax paper lubricates the saw blade.

When you make up your own Boulle packet, each layer should be the same width and length. Assemble the layers with veneer tape and use yellow glue to fasten the pattern on top (Photo 2).

 

Intricate cuts

Before you begin cutting, drill starter holes for the scrollsaw blade in every motif (Photo 3). I usually put them at the apex of sharp corners so they’re less noticeable. I use a No. 60 (.04 in.-dia.) bit for this work (see Sources, below).

You can do the pattern cutting by hand using a fretsaw, but I prefer to use an Excalibur parallel-arm scrollsaw and a superfine No. 1 wood-cutting blade with at least 20 tpi (see Sources, below). The advantage of the scrollsaw over sawing by hand with a fretsaw is that it keeps the cut square to the work and allows you to maneuver the work with both hands.

I generally start sawing near the center, so the packet is supported fully by the saw table (Photo 4). This is especially important if there is a motif with lines inside other parts. Despite the minuscule size of the blade, it can still be hard to saw crisp points. I run the blade back and forth, turning it slightly each time. This “carving” usually broadens the kerf enough for a tight turn. When I get near the end of a cut, I slip a piece of cardboard under the packet to support the motif. This also prevents tiny cutouts from falling through the hole in the saw table. The leaves on this particular design have veins, made from saw kerfs, which will be filled with dark epoxy during final glue-up.

As I cut individual motifs free, I place them on a felt-covered tray that is larger than the final piece (Photo 5). The felt grips the pieces, preventing them from sliding and getting lost. You can discard the wax paper and sacrificial veneers as the motifs are cut out, but keep the brass and wood layers together.

 

Preparing the inlay pieces for gluing

When you’re done cutting, you’ll be left with two “grounds,” the large pieces into which the inlay will be placed. One is wood, into which the brass will be inlaid (the première partie), and the other is brass, into which the wood will be inlaid (the contrapartie). Glue a piece of kraft paper to the top side of each ground, using yellow glue or hide glue. This creates a bottom for each of the cavities where a motif will go.

I typically assemble the première partie and contrapartie at the same time (Photo 6). Glue the brass piece into the wood ground, then glue the corresponding wood piece into the brass ground. Use a small dab of yellow glue on the back of each motif. You’re putting the assembly together upside down, so you should be gluing down the shiny side of the brass and the papered side of the wood. Do your best to keep the kerf from the saw blade even all around each motif.

 

Gluing the inlaid panels

With the inlaid pieces glued to the kraft paper, you’re ready to glue them to the substrate that you will use in the cabinet construction. Traditionally, hot hide glue was used in this step, but I prefer the strength and workability of epoxy (Photo 7). It holds the scuffed brass and wood veneer to the substrate and fills the voids left by the saw blade, including those of the leaf veins. I use black wood dye to darken the epoxy so it matches the color of the bog oak.

For the cabinets shown here, I used MDF as a substrate, cutting the core pieces oversize so they can be trimmed later on the tablesaw. You can do the glue-up with clamps, a press (as I did), or vacuum equipment. Lay up the panel as follows: On the bottom place a thin sheet of rubber. This will absorb the bumpiness of the panels, with their differing thicknesses of brass and wood. For one-time use, non-corrugated cardboard will do. On top of the cushioning layer, lay newspaper or wax paper to prevent the epoxy from sticking to the cushion. Next, place the inlaid sheet, with the scuffed side of the brass up. Coat your core piece liberally with epoxy and turn it upside down on the inlaid sheet. Coat the other side of the core with epoxy, and cover with a piece of backer veneer. Top with a newspaper, a caul, and then clamp (Photo 8).

 

Cleaning up the panel

The panel will be plenty messy when it comes out of the press, but it’s immensely rewarding to watch the inlaid pattern emerge during clean-up.

Use a cabinet scraper to remove the paper (Photo 9), then switch to a double- cut *** file, working from all directions. Don’t file too vigorously, or the heat will soften the epoxy. I usually switch back and forth between the two panels so they stay cool.

When the designs begin to appear, switch to hand sanding (Photo 10). Although this is tedious, it’s necessary to avoid heating the brass. Any voids that you discover can be filled with the tinted epoxy.

 

Trim and finish the panels

Once the panels are clean and flat, they can be trimmed to fit the intended cabinetry. Brass is soft enough to be cut with carbide-tipped blades, but use a high-quality ATB combination blade. The brass will tarnish unless it has a protective finish. Traditionally shellac was used, but I prefer sprayed-on lacquer.


Fig. A: The Boulle Work Packet

Click any image to view a larger version.


1. The essence of Boulle work is cutting intricate patterns in a packet consisting of thin brass sheet, dark-colored veneer, waxed paper, and sacrificial veneers, that are placed on the outside for stiffening. Veneer tape holds the layers together.


2. The pattern is glued on to the packet using yellow glue. After sawing the packet, it’s possible to separate the layers, so that two complementary inlaid sheets can be made.


3. Drill starter holes for the scrollsaw blade inside every motif, using a tiny drill bit. The best place to locate these holes is in sharp corners, where they’ll be hard to notice.


4. Cut out the pattern using a scrollsaw with an extremely fine blade. Cut directly on the lines.


5. Arrange the cutouts on a felt-covered board that is larger than the finished sheets will be. When you’re done, separate the packet and you’ll have a wood background and a brass background, each with the pattern cut in it.


6. Assemble the inlaid sheets by gluing both the ground and the inlaid cutouts onto a piece of kraft paper, using yellow glue. This will hold all the pieces together. Keep the gap around each piece even.


7. Coat the substrate to which you plan to attach an inlaid sheet with epoxy. In this case, the glue was colored black to match the dark veneer. The epoxy fills the kerf left by the saw blade and firmly glues both wood and brass.


8. Press the assembly until the epoxy sets. You should epoxy a veneer to the back of the substrate for stability, and use a rubber or cardboard cushioning layer against the inlay work, because it’s bumpy.


9. Scrape the paper off the finished panel, using a cabinet scraper, and then use a file in all directions to level the panel. Work slowly so the brass stays cool; heat breaks down the adhesive.


10. Finish by hand sanding, using a hardwood block behind the paper to keep the work flat. Start with 80 grit and progress to 400. When you’re done, lacquer the panel to keep the brass from tarnishing.


Intricate inlaid patterns have been made for centuries. The author’s cabinets capture the glory of the traditional Boulle technique, with modern tools and materials.




Sources

Note: Product availability and prices are subject to change.

Cardinal Engineering, Inc., cardinal.eng@misslink.net, 309-342-7474, Brass sheet stock (.032) and No. 60 .04-in.-dia. drill bits.

Woodcraft, woodcraft.com, 800-225-1153, No. 1 scrollsaw blades.


This story originally appeared in American Woodworker April 1999, issue #72.

April 1999, issue #72

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