Thursday, January 26, 2012

ADA Chevalet

One of the highlights of my various trips to Paris to study with Dr. Pierre Ramond at ecole Boulle occurred in the spring of 1996. I had just arrived and was visiting my friends at the Musee des Art Decoratifs, next to the Louvre. As I walked into the conservation lab, each of the workers walked up to me and shook my hand, congratulating me on my success. I had no idea what they were talking about.

I was shown a copy of the newly published volume II by Pierre, "Chefs D'Oeuvre des Marqueteurs" (Masterpieces of Marquetry) which included my photo and a brief paragraph on page 62, talking about marquetry cutting saws.

It read: "The marquetry donkey is a typical instrument of the Faubourg Saint-Antoine. Unknown to provincial and foreign marqueters, it is remarkably light and easy to move." And: "The perpetual transfer of techniques between continents can be illustrated by Patrick Edwards' equipment." I was being celebrated for exporting the particular Parisian technology of cutting marquetry using a chevalet.

Later, when I started the American School of French Marquetry, I built several different sizes of chevalets for the students, and hired a machinist to make the specialized hardware elements for this tool, putting together in a kit all the hardware and blueprints for sale. This made it possible for interested woodworkers to easily put together a chevalet for their own use.

Over the past decade I have sold nearly 50 kits, so I can only wonder how many of those are built and operating in North America where there were essentially none before. I know that this tool has been kept "secret" over the years, and there were a small number of artisans who knew about it or had one for their own use. However, with the internet and the classes being taught here, it has become more mainstream. The reception has been fantastic. Everyone that sees it is amazed by its operation and wants to try it.

After coaching hundreds of students in its use, I realize that since it requires some physical abilities, I must adapt my methods to a wide variety of human limitations. In ecole Boulle, all the students are young, energetic and able to operate the tool without any difficulty. In my school, we accept all ages and abilities and some of my students arrive with "limited" physical abilities.

One of the requirements of using this tool is arm strength. To set the blade tension you need to grab the outboard arm of the wood saw frame and pull it towards your body, using the biceps muscle. The knob on the inboard side of the saw frame is placed on the upper chest and the saw is squeezed together and held while the other hand tightens the saw blade screw. When released the tension of the blade is tested by plucking it to hear the pitch. It takes some dexterity and a certain amount of arm strength to do this, but, when mastered, it means the blade can be set up easily and quickly.

Another requirement is good eyesight, as well as eye/hand coordination. Using the Optivisor solves the eyesight problem, but coordination is another problem. Either you have it or not.

Probably the most "comments" I receive involve the wood seat. People who lived in the 18th century loved the solid wood seats on Windsor chairs. They were everywhere, they were durable and they were comfortable. I wonder if people who lived at that time had harder butts...One thing is sure, people today have soft butts.

Anyway, we have an assortment of cushions here for some students to use while cutting. There is no shame. When I built my first chevalet in 1976, I upholstered the seat in leather. All the chevalets I have built since have standard wood seats. One of the problems with the upholstery is that it is difficult to slide around and change your position as you work. Also, like riding a bike, after a few hundred hours of working on a wood seat, your body "adapts."

Another requirement for using the chevalet is using your feet. The feet need to rest on the pedals and hold the clamps tight against the work. Therefore, a person who was paralyzed from the waist down couldn't use the traditional tool.

I had a student who was able to walk but not able to lift their leg over the seat. I was asked to design a chevalet which would allow them to sit on their own stool and not require them to lift their leg over the bench seat.

It took me some time to work out the mechanical details, but this is the tool I just finished. It is a traditional chevalet except for the seat. I needed to add a second foot for stability, but it seems to work fine. In addition, it takes up less space in the shop, and you can use any type of seating that is comfortable for you.

So, pull up a seat and get to work.

Saturday, January 7, 2012

Why Use Reversible Glue?

I just finished cleaning up the glue room. Yes, I have a special room for glue. Not for using the stuff, but for cooking it. Over the past decade, the demand for Old Brown Glue has increased exponentially, from a few bottles a week to hundreds a month.

I never thought I would be in the glue business. I only wanted an organic, reversible protein glue to use in my restoration of antiques. I always had the hot glue pot, but there are a lot of jobs where having a slower set time and more liquid glue is an advantage. So, I began to experiment with modifying the Milligan and Higgins 192 gram hide glue that I always use to see if adding urea would lower the gel point.

The exact formula was eventually perfected, and these days the Old Brown Glue takes care of the majority of repairs in the business.

It is not obvious to some woodworkers why it is important to use a glue which is reversible. After all, if you put it together when you build it shouldn't it stay together...forever? Never happens. As the popular expression goes, "If it breaks, it will be thrown away". Never heard of that? Well, just consider the ratio of surviving antique furniture (made with reversible glue) to the amount of surviving modern furniture (made in the last century with synthetic glue).

The reason I started my business, as a furniture conservator in private practice, using only organic finishes and reversible glues is because I wanted authenticity in my restoration. I knew that the old pieces have all been repaired at some time or another, either due to accident or misuse. I found it much easier to take apart and repair those areas where traditional glue was used and much more frustrating to repair damage which had been repaired with synthetic glue.

The old protein glue usually was crystalized, due to extreme loss of moisture, and could be easily scraped away with a toothing iron, leaving a clean original wood surface. Where plastic glue was used, I needed to carefully carve away the glue with a chisel, which usually removed some of the wood surface, leaving the joint damaged. As the plastic glue tended to seal the wood pores, it was necessary to remove all of it, since synthetic glues do not bond to themselves. Any residue of protein glue was not a problem, as the fresh application of hot protein glue would completely bond to the earlier surface. Protein bonds with protein.

Synthetic glues, in general, are made of some chemical which changes into a different chemical with the addition of a catalyst. Epoxy is well known, and you always have part A and part B to mix together to activate it. Other glues activate when in contact with moisture or another chemical. All of them have a similar feature: they do not easily reverse once activated.

Animal protein glues are similar in their working characteristics to water. Water is sometimes solid, sometimes liquid and sometimes vapor, but it changes back and forth from one state to another simply as a function of temperature. Animal protein glues go from solid to gel to liquid and back again as a simple function of both temperature and humidity. It takes both. In fact, Old Brown Glue can be frozen without affecting its quality, unlike synthetic glues.

In the dry state, either as pearls, granulated or solid sheets, animal protein glues will last for thousands of years, assuming they are stored in a cool dry place. If they are in a cool but humid place, mold with begin to attack them. When cold water is added to the protein, it immediately begins to absorb the water and expand, gradually turning into a gel. The speed and amount of water absorbed indicates the quality of the glue. In the gel state mold will begin to form on the glue in a few days, damaging the glue. That is why it is important to heat it as soon as it gels.

Raising the temperature in a double boiler changes the gel to liquid. Cooking it as much as you want between 140 and 160 degrees keeps it ready to use and prevents the mold. I cook my glue in the glue pot about 12 hours a day, every day, all year long. From time to time I add water to keep the viscosity rather thin. On cold glue in the morning I add cold water. During the day, when it is hot, I add hot water. Keeping a plastic lid on the glue pot helps reduce the evaporation. I always keep a stainless steel meat thermometer in the glue to monitor the temperature.

Protein glues set initially by loss of heat, which only takes a short time, and then fully cure by loss of moisture, which can take overnight. Old Brown Glue sets by loss of moisture, so it has a much longer open time and cannot be used for hammer veneering or rubbed joints. On the other hand, it has a very liquid viscosity which allows it to penetrate deep into fine cracks. It also cleans up easily with cold water, using a sponge, toothbrush or paper towels, and doesn't damage original finishes on fine antiques.

The secret to reversibility of protein glues is that you need to both hydrate and heat the surface of the glue. Heat alone will not do it. Once you figure out how to get water and heat to the glue it will liquify. It doesn't matter how old the glue is. I can take apart 18th century joints and apply a hot wet rag compress to the joint and easily remove all the old glue. Doesn't take long and conserves the wood joint as it was originally made. Add fresh glue and clamp. Easy.

There are other advantages. Last week I finished cooking a large batch of Old Brown Glue and my wife came in and said she wanted to go to lunch. I said that I just needed to stir the glue once more and I would join her. Soon after we were sitting in our local eatery across from each other and I noticed a strange look on her face as she looked at me. Looking down at my favorite Pendleton shirt I was shocked to see gobs of glue running down the front onto my pants. I guess I had been in a hurry to stir the glue and splashed it all over me.

It was a very unpleasant lunch. I got all Monk on myself, thinking everyone in the place was staring at me. I was sticking to the table, the napkin, the chair. We quickly ate and I returned to the shop, taking off my shirt. By putting it in hot water I was able to completely remove all traces of the glue. When it dried you never knew anything was wrong.

Imagine if that was a toxic, plastic, non reversible, synthetic, modern glue..."If you get that stuff on your Pendleton, it will be thrown away!" Surely you've heard that old saying!

Monday, January 2, 2012

Federal Card Table

I am always ready to preach the virtues of animal protein glue, as well as traditional hand work.
I have written numerous articles on using glue and relating my experiences over my career with this unique material.

It occurred to me that, in Europe, the lessons of using natural glues were handed down from grandfather to father to son, but in America that tradition was not so common. More often than not, American woodworkers get their information from reading articles, other woodworkers, or too often, from the young salesman at the hardware store.

Since the early 20th century, American woodworkers have been using synthetic glues, some of them toxic, none of them really reversible, instead of cooking glue in a double boiler.

Therefore, I decided to write an article on what your grandfather neglected to tell you about protein glues. It appeared in Issue #197 (March/April 2008) of Fine Woodworking under the title: "Hide Glue, Age-Old Technology Has Unmatched Advantages."

Since some of the features of hot glue are its fast tack and easy clean up with water, as well as the fact that it doesn't stain the wood and is transparent to finishes, it is perfect to use for inlay, and hammer veneering techniques. So I needed a project which could put this glue to good use, and selected a simple Federal card table.

I had in stock a quantity of nice large Honduras mahogany crotch veneer, and I picked out three matching sheets for the top. It was a simple matter to shape the apron and legs at the bench and I used the liquid Old Brown Glue to glue up the bricklaid apron elements. I went through Montgomery's American Federal book and found some designs for the shell and eagle marquetry features. Those were cut out using the "chevalet de marqueterie" and shaded in hot sand for dramatic effect.

After the article was published and the table was finished, I sold it to a client who lived in Reno and delivered it there before I could even get a good photograph of it for my use. Years went by and I forgot about the table, until this client moved to San Diego and asked me to pick up the table for cleaning.

Now that it is back on the bench, I am pleased that it looks "right" and that the workmanship is "not bad". It could use more polish, as I only put a few thin coats of shellac on it before it left the shop. After a good cleaning and more polish, I expect it to look even more authentic.