Color constraints

The French have a term for marquetry. They call it “painting in wood”, and to a degree that is exactly what it is. Different woods are chosen according to their color and figure depending on the needs of the image. The problem with this description, however, is that the color palette offered by nature is constrained. Predominately brown, woods range in hue from oranges to yellows. Greens are quite limited. Occasionally, exotic species provide materials outside of this range, reds and purple, for example, but I know of no blues. Faced with this situation, the marqueter must decide whether to adhere to these limitations, or try a different route.

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Raw sycamore veneer

One answer has been to dye veneer to the shades needed. Wood, usually light colored, is cut, or sliced into thin sheets which are immersed in vats containing the appropriate dye liquid. This offers great flexibility as, conceivably, any color veneer should be possible. According to Arlen Heginbotham, Associate Conservator in the Decorative Arts and Sculpture Conservation Department at the J. Paul Getty Museum, this was Oeben’s solution (pun intended). Though this appears obvious in hindsight, it was not always the case. One of the difficulties in assessing old marquetry is that the dyes are unstable. So, the colors of the woods deteriorate with time, making it difficult to conclusively identify species. During my initial studies of the marquetry top, I consulted three sources for wood identification. Each of them differed significantly! Wood that one source claimed was ebony, was actually holly whose green dye had morphed into black with age!

Thankfully, modern dyes are more colorfast. However, they are not without their issues. For starters, it can sometimes be difficult to obtain the appropriate veneer. Holly and boxwood, for instance, are currently vexing. Having different densities, and properties, each species behaves uniquely. Just because two woods are “white” doesn’t mean they’ll result in the same color when dyed. The next challenge comes in determining the proper color “recipe”. Experimenting with differing concentrations on samples is the only certain method of which I’m aware to address this. As you can imagine, it’s a slow, resource intensive process, which isn’t perfect. The goal is to get uniform color throughout the thickness of the veneer. That way the color doesn’t disappear when the completed surface is worked. Owning to the nature of wood, I have a harder time making this happen with light versus dark colors. Orange on sycamore, for example, still hasn’t completely permeated after more then 16 hours of boiling (with two plus weeks of sitting in a cold bath!) while dark green took about eight.

Sycamore veneer dyed dark green

Sycamore veneer dyed dark green

And so it goes, cooking small five inch squares in test batches until the “proper” color is achieved. Waiting a day or two for the wet sample to dry. The true color doesn’t show until the excess moisture has been removed. Then it’s on to production. At this point, I have a green I’m pleased with, and an orange that I think will work. That leaves a blue, light purple, and two more shades of orange. Looks like I’ll be cooking wood for a few more weeks…

Cooking veneer dye samples to perfect the color recipe

Cooking veneer dye samples to perfect the color recipe

Parquetry

Parquetry is defined as a repeating geometric pattern in wood. As I understand, in French this is referred to as “jeux de fond”. Before you comment, yes, the same term is used for flooring with a repeating arrangement.

A parquetry pattern of diamonds and chevrons covers the majority of Oeben’s table both inside, and out. This is, perhaps, the easiest facet of this project to re-create in my opinion. To begin identify the pattern. In this case, it’s a series of chevrons symmetrically distributed about the center line at their low point.

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From a photo, I counted eight complete chevrons across the front apron, four to either side of the center line, with a half-chevron to each side. The final piece of information is knowing the height of the complete chevron. I luck out in this case! The complete chevron spans the height of the main box, a dimension with which we are familiar already!

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Using this information, I drew a paper pattern without making any linear, or angular measurements!

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This is my preferred method of operation as it reduces induced errors that can creep into measurements. While I have no evidence to support the claim (at present), I’ll bet that this was the way Oeben operated too.

Since there are multiple identical pieces in a parquetry design, the information shown on the template can be used to create cutting jigs. I chose the “slow road” in this case, laying veneer strips directly on the template, and marking/cutting them. This was a prototype, and I won’t be doing that for the final version.

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With sufficient numbers of pieces cut, assemble the design as a large sheet. It should have plenty of overlap. Various other elements, like the purpleheart frame will get cut into this sheet of chevrons for an exact fit. Drawer fronts are veneered from the “scraps” leftover when their apron cavities are trimmed. In this fashion, the pattern is preserved. Everything lines up.

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Changing it up

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Progress on the prototype carcass has reached a pause point while we patiently await the mechanisms.

The carcass aprons have been blocked out. That is, the joinery is complete, but the pieces have not been shaped according to their final profiles. This must occur after the mechanisms have been installed. To attempt to work in the reverse order would be challenging to say the least!

This provides an opportunity to focus on other areas, currently parquetry and marquetry.

Legs! – The making of…

I wanted to back up a moment, and explain how the legs got their start…
As with any cabriole leg, it begins with a pattern. From where this pattern originates is a mystery at least to me. I’ve consulted with several folks, but no one seems to know of a good design reference on the subject. The best I’ve found to date is the information provided in Jeffrey Greene’s American Furniture of the 18th Century. In this case, I am fortunate to have pictures of the Oeben, both from the Getty’s website, as well as from my time with the original.

Front view of the Oeben table

Front view of the Oeben table

With this photo, and knowledge of the leg height, I have everything necessary to re-create the profile. Simply project the image onto a sheet of paper with two marks representing the height of the leg, then trace! The profile is symmetric, being cabriole, so this single profile can used on both sides of the leg blank without concern. Many thanks to the ladies at The Arts Council for allowing me use of their projector for this exercise.

At first, the curvature of the leg is subtle. That’s because the knee is hidden by the ormolu. Same for the “feet” which are covered by sabot. I had to interpolate in these areas which isn’t really a concern since, if I got it wrong, a) I can refine the profile during later stages, and b) it’s going to be hidden by ormolu anyway! The profile can be transferred to template stock, 6 mm thick plywood in this case. I use graphite paper for this…

Leg profile on template stock.

Leg profile on template stock.

Now, it’s a straight-forward exercise in coarse, medium, and fine…Begin sawing out the rough profile, then refine it successively using rasps, scrapers, files, and sandpaper. The resulting profiles should be smooth, continuous curves without noticeable discontinuities. As I work, I’ll run my fingers along the edges while looking away to test. It’s easier to feel imperfections.

Tools used to refine the leg profile

To refine the template, use rasps, scrapers, files, and sandpaper.

With the template “faired”, choose stock for the legs. The legs of the Oeben table are completely veneered, so none of the “core” grain is visible. If, however, you aren’t planning to veneer your piece, consider the grain direction of your blanks carefully. Lines running diagonally through the end grain will yield straight grain down the legs. Lines parallel to the faces in the end grain will produce bull’s eye patterns at the knees. Mill a face, and a perpendicular edge. Don’t bother with the other two sides. They’ll be removed in subsequent steps. Just be certain to use these two reference faces for all of your layout.

Cabriole leg layout

Trace the template profile on two adjacent faces of the leg blank.

Trace the template onto the blank aligning the “back” along the arris between the two reference faces. The “back” is defined to be the flat portion of the leg block at the top which winds up inside of the piece. You’ll have to flip the template over when switching faces. I like to strike lines defining the top and bottom extents of the template, and carry those around the blank to aid in alignment. Another point I neglected to make in my previous posting on the legs, it’s best to layout, and cut the mortises while the blank is still square, before you commence cutting.

Hopefully, this provides a more complete explanation of the cabriole leg process…