Tuesday, August 12, 2014

Tarsia Geometrica Part I

English Jeux de Fond Coffer
I remember clearly the first time I was in France and visiting an atelier where several ebenistes were working.  Looking at their work, I noticed some of the marquetry was very geometric.  In my efforts to impress them, I used the term "parquetry."  They looked at each other with obvious blank expressions, and then looked at me as if I had just fallen off the turnip truck.

"C'est du placage, pas du parquet. Nous ne sommes pas menuisiers, nous sommes ébénistes."

(Translation:  "That's veneer, not flooring.  We are not 'menuisiers', we are 'ebenistes'."  In point of fact the former works in solid wood, and the latter uses veneer.)  It turns out that it is common for English speaking woodworkers to confuse the term for geometric marquetry with the profession of laying solid wood flooring.

They were helping me to understand that using the English/British term "parquetry" is not correct when  discussing a form of marquetry generally known as "frisage" and in particular "tarsia geometrica."  Another term for a version of this type of decoration is "jeux de fond."  Pierre Ramond's book discusses these terms in great detail, but there is general confusion about what they mean exactly.

Simply put, the overall term for the process of making this work is "tarsia geometrica."  This term includes other specific terms for different patterns which all use repetitive patterns in wood to achieve a decorative surface.

"Frisage" is used to describe simple book matching of slip matching of larger veneer surfaces, usually to create a background.  Normally, frisage work involves using the same species of wood in a way that creates a pattern.

"Jeux de fond" is also referred to historically as mosaic work, as it involves much more complicated patterns of shaped elements, usually with different species of woods.  In many cases it creates a 3-D effect.  The most well known pattern is the cube, made up of three different pieces, each a different color density.  This pattern is also found in quilting and tile work.

Recently, I had the opportunity to restore several excellent examples of tarsia geometrica.  One was an Italian commode, made late in the 18th century.  The other was an English coffer, made early in the 19th century.  Each one needed extensive work in re gluing the marquetry and re polishing but in the end they looked magnificent.

I will discuss the commode in the next post, as it included a technique known as "tarsia a toppo" and I want to clarify why that is different, even though the final results are similar.

I want to start with the simple cube design:

Cube Design on Assembly Board

This is a rather common design and forms the basis for what follows in this discussion.  The cube is made of three elements, each one identical to the other in shape and size, but different in species.  By changing the wood species and grain direction of each piece, you can vary the effect.  I use a simple plywood cutting board, with a 60 degree slot for my back saw, which has little or no set to the teeth.

I will explain more about the cutting jig soon, but today I just want to discuss how this motif is used in a complicated jeux de fond pattern.  To illustrate further, consider if the cube elements were cut in one size and then also cut twice as long and combined.  This would be the result:

Large Cubes with Small Cube

Now if you take the same design and turn it 180 degrees it changes:

Large Cubes with missing Small Cube

This effect is an optical illusion that the brain automatically understands.  Since light naturally comes from above, the brain computes the top of some form as being lighter.  When the design is rotated 180 degrees the brain understands it as a completely different image.

I thought I would make a sample panel which incorporated both of these designs with a common joint in the center:

Compare Left side and Right side

Another experiment I tried was to make a three dimensional grid:

Experimental Grid design on Assembly board
There are lots of ways you can develop different designs with this idea.  The English coffer at the top of the post uses the cube in a very imaginative way.  There is a lighter grid floating in front of a darker grid, which in itself forms a cube space.  To add to that, there are three smaller cubes at the intersection.
It is a wonderful pattern:

How Many Cubes?
So, during restoration, I took the time to trace this pattern for future projects:

Tracing with Wood Species and Grain Direction
I began to wonder where this amazing pattern originated, so I picked up my copy of Roubo and started looking at the illustrations.  When in doubt, always start with the source reference material.  To my amazement, I found the direct source in Volume IV.  Here is the original Roubo design and after that my tracing of the pattern, showing it to be simply a repetition of the Roubo motif:

Roubo Volume IV

English Coffer derived directly from Roubl

Here is the top of the coffer with the nautical compass in the center:

Coopered oak top with jeux de fond marquetry

Next post will continue this analysis and compare with similar marquetry decoration.


Follansbee said...

thanks for all these great photos & explanations - what tricks your eyes & mind can play on you. great stuff
Peter Follansbee

Chuck said...

The brain reels not to mention the eyes! What is there about wood that seems to enhance trompe l'oeil effect more than other artistic media? This is evident in other masterpieces of marquetry too. Thank you for your design exposition and knowledge.

Mat Nedeljko said...

Thank you Patrick for the wonderful example and the lresearch to link it back to the original source in Roubo. It is astonishing to me that these patterns were in use two centuries ago and that they still have power to amaze us today!

Mat Nedeljko said...

Patrick thank you for the wonderful examples and the research to link this back to the original source in Roubo. I find it astonishing that these patterns were discovered two centuries ago and they still hold such power to amaze us today. I am going to have to incorporate this into one of my future projects!