Shellac and French polishing

During my stay at the Marc Adams School, I had a chance to refresh my French polishing skills. Today, French polishing has become synonymous with a high-gloss finish. To woodworkers, however, this term is specific to a technique for the application of shellac. Shellac is a natural product derived from insects that range in Southeast Asia. It is collected, and processed to remove the sticks, leaves, and other “foreign matter”.

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Next, it’s ground into coarse particles, and separated into various colors…

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Further processing leads to it in the familiar “flake” form with which woodworkers are familiar…
This is an over-simplification of the procedure. The interested reader is referred to Vijay Velji’s article, “Shellac’s Amazing Journey” in Fine Woodworking number 215.

When I first learned French polishing, the process began with pore filling using linseed oil and pumice. Patrick Edwards, however, omitted the oil simply applying the pumice with the pad moistened with alchol. His experience has shown that once the oil has evaporated through the shellac, as the piece ages, the accumulated pumice powder shows through. The alcohol dries well before the shellac is applied, and so the excess powder can be easily removed. This technique has the added advantage of burnishing the surface to a glossy shine, almost evident in this photo…

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This result was achieved with under an hour of effort to facilitate the seminar. However, when properly executed over the course of several days, you can understand how the surface will shine. Once, and only once this treatment is complete, can the finisher begin the shellac applications. Keep in mind that French polishing is a slow process requiring patience, and persistence. It is not meant to be rushed, and usually occurs over a period of several days to weeks.

So why do woodworkers torture themselves with this process in this “modern” day? For several reasons:
• French polishing can be performed with simple, inexpensive materials – it’s just alcohol, oil, shellac, and cloth! No fancy spray guns, or figuring out which brush type to use!
• Shellac is an easily repairable medium. Many times affected pieces can be treated on site whereas other finishes necessitate having to haul the damaged piece back to the finisher’s shop. That’s an added expense!
• Finally, as I mentioned before, shellac and its solvent, alcohol, are natural products. They’ve been used for over a century with few to no ill-health effects. In fact, shellac is one of the few “finish” materials that is an FDA approved ingredient in medicines and food products! Ever wonder how the produce in your local grocery got its shine? It has been coated with shellac!

Traditional French marquetry

I am back from another productive trip to Marc Adams School of Woodworking. Thank you to everyone for making my stay pleasant, and comfortable, as usual. On this trip, I had the opportunity to make some new friends, and become reacquainted with many old ones. My only regret is that we couldn’t spend more time together. These trips are always so hectic!

As I mentioned previously, I spent a week with Patrick Edwards learning French marquetry technique. We focused on the Boulle process, also known as tarsia a incastro. In it, the various colored veneers are bound together in a packet and cut according to the design. The packet is opened, and the picture assembled by placing the veneer pieces of one species into another. Any voids between pieces are filled with a wood dust and hide glue mastic, nearly imperceptible to the casual observer. This fundamental technique offers the marquetry craftsman the ability to generate multiple copies of a design rapidly.

A marquetry triptych

A marquetry triptych

Cutting takes place using the chevalet de marqueterie, or marquetry “easel”. This uniquely French tool allows the operator to hold the veneer packet vertically at eye-level while guiding a saw along a steel rod adjusted perfectly perpendicular to it. The accuracy is such that a piece taken from the front of the packet fits within the corresponding “hole” in the veneer on the back of the packet. The manually operated saw also offers a greater degree of control than a typical powered scroll saw. Small delicate pieces can be produced which might otherwise be lost in the machine’s vibration.

Once I’ve gotten back on schedule, one of the higher priorities on my to do list will be to tune up my mini-chevalet. My experience this week gives me a better idea of how it should work!

A mini-chevalet for marquetry

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Nearly a year ago, I began building a mini-chevalet to cut the marquetry in the table top. Patrick Edwards, French-marquetry method master, provides a great explanation of a chevalet if you’re unfamiliar with this tool.

Essentially, it’s a hand-powered scroll saw mounted on a horizontal rail. Mine is built entirely from scrap 1/2 inch plywood, uses nylon bushings, and fret saw blades. The saw is constrained to move perfectly along this line, with the veneer packet held in a vertical spring-loaded (at least in this version) vise. The advantage to this gizmo is that relatively thick veneer packets can be cut with the guarantee that a piece from one end of the packet will fit into the hole on the other end. We want nice tight joints in marquetry with no gaps between the pieces.

The major differences between this version, and a full-sized chevalet are cutting capacity, and comfort. The full-sized model is a sit-down affair with foot pressure controlling the grip of the vise. It’s also capable of working longer pieces as governed by the length of the saw arms.

This will be my first introduction to this tool. It’ll also serve as a prototype for when I get around to building a full-sized version. However, there are two limiting factors on that last point: materials, and shop space. The first is easy to correct, it just takes money! While the second point is also solved by money, that solution is vastly more expensive.

The design is based off one Don Williams made. I saw pictures of his on the Smithsonian website, and corresponded with him. He graciously provided me with pictures from multiple views. Donna Hill shared more pictures she took at Woodworking in America a few years back. The process has been a great learning experience, and I expect that it will continue to be as I begin using it.