If you have not read Jack Planes post on hide glue, you should.
If you have not read Jack Planes post on hide glue, you should.
Orchard Lawn, the Italianate home built in 1868 by Joseph Gundry is the home of the Mineral Point Wisconsin historical society and their museum. The society has many photographs of how the house was furnished when it was built. They have found many of the original objects in the local community and are searching for the rest. In the attic of the home they found samples of the original carpets and wall coverings. The company that made the carpet is still in business in England. That company remade the carpet in 24 inch strips as the original was done, they then sent a man from England to hand sew the strips together and install the carpet. The wall coverings and murals are also being recreated as funds become available.
About a year ago I restored 3 chairs for the Gundry House. Not long ago I visited the chairs to see them in their setting. The pictures are poor, there was no light and I did not have a tripod, but you can get the idea.
One of the above two had a broken leg and they both needed the leg joints to be reglued. I had to remove the seat upholstery and then put it back.
This one also needed to be reglued, and the seat had several holes and rips. I removed the seat and sewed it to a black backer cloth and put it back on. The backer reinforces the the original upholstery and helps hide the holes. The backer has a texture that matches the original and with the backer in place its hard to find the holes.
If I get back I will take a tripod and replace these pictures.
A recurring problem in the repair of upholstered furniture is the degradation of the edges where the upholstery is tacked to the piece. Many upholsterers are not wood workers, so when removing old upholstery you never know what you will find. The picture below is of an Eastlake chair that has been recovered so many times that there is little left to drive tacks in to. You can see that the last man to upholster this chair drove tacks into the face of the rail in order to attach the fabric. I have seen all kinds of attempts to repair this type of damage, every thing from nailing wood to the frame to Bondo auto body filler.
The first and most difficult task is to remove all the old tacks in the edge of the rails. Most upholsterers will just leave many of the old and broken tacks in place. The remnant tacks will damage your edge tools when repairing the edge of the rail.
A rabbet is cut into the edge of the rail with a router plane and chisels.
Replacement wood glued into the rabbet.
All materials expand and contract due to heat, and in some cases moisture, and in some cases both. Each material expands and contracts at different rates. Different metals expand at different rates due to heat, as the metal warms up the molecules move apart and as it cools they contract. Wood primarily expands as it absorbs moisture and contracts as it dries out. Different woods expand and contract at different rates.
The amount of expansion in relation to the amount of heat or moisture is called the coefficient of expansion.
When we build objects we need to take this expansion and contraction in to account, we primarily think about wood movement but in some cases we must also be aware of the movement of metal. Wood glued directly to metal always fails eventually, because of the difference in expansion rates, it doesn’t matter what glue you use. Even a flexible glue like construction adhesive will eventually fail due to repeated expansion cycles, it’s like bending a piece of wire back and forth until it breaks. Even if there was a glue that would not fail the difference in expansion rates would cause the object to warp and deform. When laminating metal to wood one must allow for movement. We must also consider the effects of compression set. If you are not familiar with compression set it is explained here.
Below are several tools made of brass and wood.
Here is what happens when wood is glued directly to metal.
Notice the piece of brass that is proud of the wood.
The brass is dovetailed into the wood allowing for movement.
Mechanically attached to the wood.
Fastened in the center allowing movement
There are two places where a finish can fail to adhere. The finish can fail to stick to the substrate (substrate adhesion) or it can fail to adhere to the previous coat in the finishing system (inter-coat adhesion). There are two types of adhesion that affect a finishes ability to stick to a surface: mechanical adhesion and chemical adhesion. Mechanical adhesion to the substrate is affected by how you prepare the surface, sanding or planing. A surface can be too finely sanded or too smooth for some finishes. Inter-coat adhesion is affected by scuff sanding between coats or the ability of some finishes to burn in to themselves or chemically bond. Both types can be affected by contamination.
In my experience most adhesion problems occur with the modern finishes, polyurethanes, waterbornes or two part finishes. Adhesion failures with shellac, lacquers or traditional varnishes seem very rare. Problems when mixing waterborne and solvent borne products in the same schedule are common.
Here is a partial list of causes for adhesion failure in no particular order.
This is a rocking chair that someone stained with a heavy coat of oil based stain and then top coated with a water borne varnish, then I got to work on it.Same rocker. It was stripped and refinished with lacquer based products.
“Too often professional insecurities are masked in impenetrable language and professional reputations are buttressed with unnecessary complication, and confusion.” David Savage
In 1965 I enrolled in college and started a program of study in architecture. As one of the requirements of the architecture program I took a sketching class, the purpose was to learn to draw the trees around the buildings I would design. I also took my first design class that first semester. One thing led to another and before I knew what happened I was an art major. After three semesters I took a short vacation in south east Asia, when I returned I went back to school and continued to study art and design. I eventually finished college and got a job teaching art and design. First let me tell you that I’m not writing this to brag about my college experience, what I’m trying to say is that I graduated from a respected University with an MFA in art and design and didn’t have a clue about how to teach or explain design to anybody, I knew all the vocabulary, I had read all the books I could talk design with the best of them, but I knew something was missing, it didn’t all make sense, it didn’t all fit together, I was still confused.
Studying design is one of the most confusing and frustrating things one can ever attempt to do. All you have to do is read the Wikipedia page on design and try to use what you read to design a piece of furniture, or any thing else. One of the problems is that all the words used to discuss design have multiple meanings and the word design itself has multiple meanings. The on line dictionary lists seventeen definitions for the word, both noun and verb. Design can be a process or it can be the results of the process. Sorting out and making sense of all the written material on design can be a daunting task to say the least. Much of the material is not only confusing it is down right contradictory. Much that is written on design is based on philosophy and if you don’t share that philosophy it’s not helpful. For example the statement “Form follows Function“, this is a statement of a philosophy of design and if you don’t embrace it, it won’t help you design anything, however that statement is one of the founding principles of 20th century design.
Well I got lucky, one Friday after work, while sitting in a tavern drinking beer with a bunch of art teachers I mentioned that I was about to teach a beginning design class and had no idea what to do. I asked did any body have a Design I syllabus? There was an old gentleman sitting there that had studied at the Art Institute of Chicago in the forties. In a couple of hours in that saloon he taught me a structure, a way of thinking about design that tied it all together. A way to simplify design.
All the confusion was not necessary, There is a simple explanation and process that allows us to understand good design. There is a set of elements and principles that explain good design from all periods and within all philosophies and cultures. In design at least I think there is a theory of every thing. The theory is not a formula or cook book for creating good designs but a way to analyze and study a good design. If we can understand what makes one design more successful than another, it may help us improve our own designs.
In the previous paragraph I repeatedly used the term “good design”, I’m not sure good design really exists. I think there are more successful designs and less successful designs. Albert Sack said Good, Better, Best.
Design is not period specific. The elements and principles of visual design are based on how we see and how our brain interprets what we see, not when we see. The elements and principles apply to all periods. These elements and principles can be used to discuss and analyze any piece from any period. In furniture design there are archetypes that do not change. If you are going to sit on a chair your legs need to fit under the table during any period, if you are going to sit on the floor the table needs to be lower. What does change is culture, engineering and style. An example of change in engineering is drawer construction, during the William and Mary period drawers were often nailed together, during the Chippendale period dovetails were used. The high versus low table is a cultural change. While culture modifies how we interpret what we see the elements and principles still apply.
What is Design?
Design is the organization and manipulation of the elements of design through the principles of design to achieve an out come. That’s it, it’s that simple, you have elements, principles and outcomes.
The Elements of Visual Design: There are three primary elements and one secondary element of visual design. The primary elements are line, value and color. The secondary element is texture. These are the elements of visual design because these are the basic building blocks of what and how we see. Not only are these the basic building blocks of what we see they are the basic building blocks of what we design.
The Principles of Design: There are four principles of visual design. They are repetition, variation, opposition, and transition. These principles are what happens to or what can be done to the elements. Any visual element can be repeated, it can be varied, it can be opposed or it can be in transition.
Outcomes: When we design we use the principles to manipulate the elements to create a result or outcome. This is what visual design is at it’s basic level. Form, balance, proportion, motif, shape and all the other similar concepts related to design are all results or outcomes of the design process.
Texture: Texture is a special case. Texture can be the result of the repetition of an element so in that respect it is an outcome, but at the same time it can be manipulated by the principles as an element.
Time: Time is another special case, time is neither an element or a principle but it needs to be considered in the design process. It can be used as an element, Alexander Calder used time as an element when he built his mobiles. The mobiles moved so they had to work at any moment in time both visually and in their engineering. When we walk around a piece of furniture it’s engineering does not change but it changes visually from moment to moment as we move so time effects the visual design.
Repetition with Variation: Repetition and variation are the two most important principles. It is repetition that unifies a design and ties it together, it is repetition with variation that adds interest. The human mind is always subconsciously trying to make sense of and create order in our environment. Our minds are always searching for likeness, looking for the same color, looking for the same shape. We are constantly subconsciously putting thing in groups, it’s one of the ways to make what we see simpler.
When ever we build a piece of furniture or anything for that matter, unless we are copying someone else’s design we are designing. If you create an object it is designed. The question is not is it a good design or bad design. The question is does this piece achieve our intended outcome, if yes, why? if no, why not? There is no formula that leads to “good design”, but there is a way to analyze a design after the fact. In future posts I plan to use these ideas to discuss different pieces and hopefully make more sense of this post.
One of the most common questions I receive is “can you remove the warp from this_____” fill in the blank with something like table leaves, drawer bottom, or table top. The answer is always the same. ” That depends”. Anything can be fixed if you are willing to spend enough money. However sometimes it’s just not worth the effort and it’s just easier to replace the part or the whole piece.
In this post I’m going to talk about a method of straightening a warped board, it doesn’t always work, but many times it does. If you are going to try this don’t start right out with your dinning room table or your grandmothers antique desk, practice on scrap boards until you have had some success, this is not as easy as it may appear in this post.
Wood is made up of cells that are many times longer than they are wide. The vast majority of the long cells run parallel to the center of the tree. These cells are hollow. Imagining the wood as a bundle of straws is a common way to illustrate the structure of wood. However you must imagine the straws with closed ends and varying length to be a little more accurate.
When the wood is in the tree it contains two kind of water , free water, the water in the hollow part of the straw and bound water the water that is locked in the walls of the cell. Wood in the tree can contain as much as 75% or more water by weight depending on the species and the time of the year. When the wood is cut from the tree, first the free water begins to evaporate, when all the free water is gone but none of the bound water, the wood is at the fiber saturation point, it will be around 30% moisture depending on the species. As the wood continues to season it begins to lose bound water until it is in equilibrium with the relative humidity of where it is located. As the bound water evaporates the cell walls begin to shrink and continue until the wood stops losing water. As the cell walls shrink, the over all dimensions of the wood shrinks. If the relative humidity where the wood is located goes up the cell walls begin to absorb moisture again and begin to swell, as the cell walls swell the over all dimensions of the wood increases. This is what we call seasonal wood movement and it will take place when ever the relative humidity changes, it never stops, ever, finishes will slow it down but not stop it. If one side of a board is exposed to more moisture than the other side, the wet side will expand more than the other side and cause the board to warp or cup. If the cells cork screw through the board as they expand and contract the board will twist and untwist.
Now I know you are saying if this is true why doesn’t a cupped or warped board flatten back out. The answer is compression set. When a piece of wood is confined and it absorbs moisture it tries to expand but can’t, when it can’t expand the force crushes some of the cells, with the cells crushed it can no longer expand and contract fully, keeping it warped or compressed. Compression set takes place whenever the wood tries to expand and is restricted. It also takes place when one side of a board tries to expand and the other side does not. This is normally caused by uneven moisture exposure. Compression set also explains why joints loosen over time. It is the explanation of most cracks, loose screws, loose nails any thing that restricts the movement of the wood can cause it.
When wood tries to shrink from loosing moisture while it is restricted it will crack, check or split at the weakest point. It will split many times where it was punctured with a peg, nail or screw. A wide plain sawed board will split most often in line or near the cathedral grain.
A warped board may be caused by other issues like reaction wood, but most warping is caused by moisture or heat and compression set.
A METHOD OF REPAIR
Common knowledge says to straighten out a warped board we need to apply moisture to the concave side of the board, and if enough moisture and heat are applied to the concave side, the board will temporarily straighten out. However as soon as the introduced moisture dries out the board will go right back to the warped position or may even warp more if the process causes increased compression set.
The best chance of removing a warp is to introduce a compression set to the convex side of the board by introducing moisture to the convex side while the board is restrained from moving. This can be very time consuming and difficult if the warp is severe.
A technique I have used with some success with small tops and drawer bottoms is, 1. clamp the board straight with clamps and heavy aluminum angle irons so it is unable to move. 2. Lay the piece on the damp grass with the concave side up for a period of time, the length of time depends on how sever the warp is. 3. Leave the piece in the clamps in the shop until it is in moisture equilibrium. 4. Repeat until it is straight. A similar process can be done with steam, or even damp blotters.
Here is the carcass of an Arts and Crafts stand up desk.
The wet end has been covered with wax paper to allow the water to soak in rather than evaporate. It was then put in the sun with the concave side up for several hours. Only the warped end was in the grass the other end was on dry concrete. The second day it went back on the grass the same way but it was turned over every two hours all day.
The top of this candle stand was straightened using this method. I forgot to take a before picture, you’ll have to trust me, it was quite warped.