The following is an excerpt from “Sharpen This” by Christopher Schwarz.
One of the most frequent (and unanswerable) questions I get about sharpening is: How often should I sharpen?
The correct but unsatisfactory answer is: Pretty much any time the question “Should I sharpen?” pops into your head.
When I ask myself that question, I stop and look at my tool’s edge. Can I see a glint of light at the tip of the bevel? If I can, it’s time to sharpen. I look at my work to see if the surface is clean or if it’s marred by fine white lines or scratches in the wood. If I can see those lines, the edge is likely damaged and needs to be reground. And I think about the last few minutes of work I’ve done. If the work took more effort than expected, it’s time to sharpen.
You also have to become sensitive to the peculiarities of your tools. There are times when the tool’s cutting edge is not causing the problem. That is, you sharpened the edge, and the problem persists. What do you do then?
Well the good news is that by taking a moment to sharpen the tool you have eliminated the most common ailment of a hand tool: the edge is dull. After that, you need to consider the other parts of the tool. If your handplane is leaving a rough surface in its wake, the problem could be that its sole has become dented somewhere around its rim. So you need to file away any roughness on the sole. If the plane is too hard to push, there’s a good chance that the tool’s chipbreaker is too close to the cutting edge, which can create some impressive resistance. And if the plane is both too hard to push and it is leaving a nasty surface on your wood, there’s a good chance that the chipbreaker has slipped forward of your cutting edge and so the chipbreaker is doing the cutting – instead of the tool’s cutting edge. This is a common problem.
If a sharpening session doesn’t fix a chisel, there’s a good chance that your sharpening efforts did not cut a new zero-radius intersection. This is also a common malady among beginning woodworkers.
But in all honesty, sharpness fixes almost everything.
As you become proficient at sharpening, you will find there is a pattern or rhythm to the process, and it is mostly circular, like the life cycle of a frog. It starts as a tadpole that grows into a frog and then creates the next generation of tadpoles. With tools it is hone, polish, hone, polish, hone, polish, grind – then repeat the cycle. The following flow chart will – I hope – show you how sharpening occurs in a workshop during the long haul. It might take a chisel a year to make it around the circle. Or a week. It really depends on how much you use your tools and how hard you are on them.
The flowchart (below) begins the moment you decide a tool is dull.
Sharkskin or shagreen, in general, is used by all woodworkers. But the cabinetmakers do not use it except for the most fine parts, like shark fins that are called “dog-ear skin,” which have the finest nap of all skin and which, by consequence, scratch the work less. —André-Jacob Roubo “l’art du Menuisier”
The following is an excerpt from “The Stick Chair Journal.” “The Stick Chair Journal 2” is also now available. While supplies last, you can purchase a bundle of issues Nos. 1 & 2 at a reduced price.
James Krenov was the first woodworker I heard about who didn’t use sandpaper. That idea – no sandpaper – was so shocking that I can remember the moment it happened. My boss at the time handed me a copy of “A Cabinetmaker’s Notebook,” and mentioned that Krenov used only planes and scrapers to finish his furniture. I took the book with a somewhat skeptical look on my face. I was not impressed, but I was amazed.
Since that moment in the 1990s, I have met lots of woodworkers who eschew abrasives. They finish the work with edge tools only. Their sharp steel edges slice open the individual cells of the wood, allowing us to peer inside. The edge tools produce a shimmering glow in the wood that is almost unobtainable with sandpaper. And they do it all without producing the lung-destroying dust that comes with sanding.
Or that’s how the story goes.
FLAT & SMOOTH Egyptian woodworkers sanding a box, Fifth Dynasty. From “Egyptian Woodworking and Furniture” (Shire) by Geoffrey Killen.
Anyone who has embraced edge tools (myself included) goes through a phase where they finish projects using only sharpened steel edges. To be sure, this phase makes us better sharpeners. It makes us better users of planes and scrapers. But it doesn’t necessarily make our projects any better.
I invite you to conduct the following experiment. Plane one face of a board dead flat without any plane tracks. Then finish its other face with sandpaper, working up the grits with care to #220. Now finish both faces of the board with shellac, lacquer or varnish. Hand the board to another woodworker and ask them to figure out which is which.
I’ve done this. It’s a guessing game.
IT’S SANDED A stool in the British Museum that has been finished with sandstoning, according to Killen, author of “Egyptian Woodworking and Furniture.” Many pieces of Egyptian furniture show signs of being finished with scraping or rubbing with sandstone.
While there might be microscopic differences between surfaces that have been planed and those that have been sanded, they aren’t noticeable to the naked eye once a film finish has been applied. And people who say they can tell the difference are just guessing. (I have played this parlor game many times.)
So why learn to use a handplane? Easy! It’s usually faster than sanding. It produces little lung-clogging dust. And it’s frankly more enjoyable than sanding.
So why learn to sand? Because woodworkers have been doing it for at least 4,000 years (abrasive technology is older than the first handplane), and sanding can easily accomplish things that are difficult to do with edge tools.
In other words: You probably should learn to do both.
When I learned to finish surfaces, this was the routine: Plane the surfaces until you cannot improve them. Scrape any tear-out. Quickly sand the surfaces with a fine-grit paper to blend them and produce a consistent surface.
The above traditional technique (around since at least the 18th century) quickly produces nice surfaces. Using a combination of planes and abrasives is faster than using only planes or only abrasives (assuming we are all striving to get to the same destination).
If you don’t believe me, ask the ancient Egyptians. Or Grinling Gibbons. Or A.J. Roubo.
A FLEXIBLE RASP Chairmaker Chris Williams demonstrating how he and John Brown shaped the armbow using strips of abrasive, much like a shoeshiner.
BUT THERE’S MORE Sometimes I use abrasives to round over corners, produce fine chamfers or to fair curves. In other words, I use abrasives to shape the wood – not just prepare it for a finish. Unlike all the stuff above, this is not a known historical technique. Yet I gladly stand by it. Let’s talk about it.
I love my rasps. These steel tools allow me to shape wood without regard for grain direction or the shape of the wooden surface I’m working. I can just as easily shape a curved surface as I can a flat one. Rasps work by means of many tiny teeth that minutely scrape the wood. The fact that there are hundreds or thousands of teeth makes the work go quickly.
Each tooth of a rasp looks like a triangular pyramid. In fact, if you look closely enough, you will see that the teeth on a rasp look a lot like the teeth on a handsaw or backsaw. After drinking a couple beers, I would eagerly say that a rasp is only a little different than a saw. The primary difference is in the arrangement of the teeth. The teeth on a handmade rasp are scattered randomly on a steel blank. The teeth on a saw are arranged in a discreet line on one edge of the steel blank.
Also, the rasp and the saw make the same sound in use. They provide the same vibrational feedback to the user. And the teeth of the saw and the rasp both stop cutting when waste wood clogs up the teeth.
Sandpaper is not much different. Its teeth are randomly scattered over the substrate (paper, cloth, woven material). They also make tiny cuts. They also stop cutting when waste wood clogs up the teeth. And sandpaper makes the same “shushing” sound.
11 Reams and 6 Quire Paper Emery £10/3/0 1 Ream Sand Do (Paper) £0/10/0 — The 1800 inventory of ironmonger Christopher Gabriel of London. A ream is 500 sheets, and a quire is 24 sheets. So, Gabriel had 5,644 sheets of emery paper and 500 sheets of sandpaper on hand that day. From “Christopher Gabriel and the Tool Trade in 18th Century London” (Astragal Press) by Jane & Mark Rees.
Put another way, sandpaper is just a flexible rasp or saw. It uses the same cutting technology – tiny teeth. The only difference is that with sandpaper the teeth are bonded to a flexible backing.
So, if you don’t use sandpaper, is it because you are opposed to paper or cloth?
I’m not trying to be a jerk. I am happy for you to use the tools that please you. If you hate sandpaper, fine. Don’t use sandpaper. But don’t delude yourself into some historical reverie in the process. And don’t (as mentioned above) assert that a sanded surface is inferior.
Abrasives have been around for as long as human history has been recording its progress. They have been used in woodworking since (at least) ancient Egypt. They show up throughout history – even in the beloved Golden Age of Furniture in the 18th century. And like any tool, they are useful when used in the right place, in the right way and at the right time.
In other words, don’t make a chair seat using only #40-grit sandpaper (unless that’s the only tool you have). That’s just as peculiar as making the seat using only a scraper or a travisher. Or only an adze.
The world is filled with many good tools and questionable opinions. So, keep an open mind and pick the tools you like and that bring happiness (or, as in my case, buy groceries).
It is, above all, succinct, easy to understand and perfectly suited for the furniture-maker. As important as what is in its 160 pages is what is not. It’s not a detailed analysis of cell growth. It is not a heap of tables and equations for figuring truss loads in residential construction. It is decidedly not a scientist’s approach to the material.
Instead, “With the Grain” contains the facts you need to know at the lumberyard, in the woodlot and in the shop. It gives you enough science so you understand how trees grow. It explains the handful of formulas you have to know as a furniture-maker. And it gives you a hearty dose of specific information about North American species that will inspire you. Becksvoort encourages you to use the trees in your neighborhood and makes the case that just because you cannot find catalpa at the lumberyard doesn’t mean it’s not a good furniture wood.
You’ll learn to identify the trees around you from their silhouette, leaves and shoots. And you’ll learn about how these species work in the shop – both their advantages and pitfalls.
Becksvoort then takes you into a detailed discussion of how wood reacts to it environment – the heart of the book. You’ll learn how to calculate and accommodate wood movement with confidence and precision. And you’ll learn how to design furniture assemblies – casework, drawers, doors and moulding – so they will move with the seasons without cracking.
This week’s excerpt picks up where last week’s (on wood structure and the classification of trees) left off…
Figure 1-7 shows the three faces, or planes, of wood. Cutting the wood parallel to the ground and perpendicular to the pith exposes the cross section, or transverse face. Such a cut is in the transverse direction and reveals the growth rings, pores, rays and pith.
Cutting in a plane parallel to and through the pith reveals the radial face and is in the radial direction. This cut shows the parallel edges of the growth rings and best shows the widest portion of the rays.
Again cutting vertically through the trunk, but parallel to the pith, reveals the tangential face, or plane, which displays the ends of the rays and the wide figure of the growth rings.
Wood is an anisotropic material: It has different and distinct properties in each of its directions. In the longitudinal direction, with the length of the wood fibers, wood has its greatest shock resistance and compression strength. Hence the use of longitudinal lumber in posts, legs and other weight-bearing members. In addition, wood shrinks an insignificant amount in this direction. Yet with all its compression strength, it splits in the radial and tangential direction. In the transverse direction (cross section) wood refuses to split, yet compresses perpendicular to the grain. In ring-porous woods such as oak and ash, the concentration of large, thin-walled vessels in the early-wood forms rings of weakness. Utilizing this property, basket makers beat ash logs to separate the growth rings, lifting them off in sheets.
COLOR AND LUSTER Color in heartwood is caused by extractives. In most species the sapwood is a light, creamy tan color. Heartwood color varies tremendously among species, and even within a species, color is variable. One theory states that shading is influenced by the soil in which the tree grew. Because of the variables, color should only be used secondarily as an aid to identification. Other factors also influence color: exposure to sunlight, which hastens the development of the patina; and finishes, which alter the natural darkening or bleaching of the wood. Although color is an unreliable factor in wood identification, it is this variability, in conjunction with the figure of the grain, that makes each piece unique and adds to its aesthetic value.
Luster is the natural ability of the wood to reflect light. It has nothing to do with color or finish. Luster is most evident when the wood is planed with a sharp tool. This produces a more reflective surface with more sheen than sanding, which abrades the wood and clogs the pores. Occasionally luster can be used to identify wood. White ash, for example, is noticeably more lustrous than black ash.
TASTE AND ODOR Extractives are also the cause of taste and odor in wood. Some odors are so distinctive they can be used in identification. Aromatic extractives are most noticeable in red and white cedar, black walnut, sugar pine and sassafras. A few woods such as catalpa and tulip poplar have a rather disagreeable odor. Because most of the odor-causing extractives are volatile, they can be detected only in green or freshly sawn wood. Taste is usually not pronounced in wood. Rather, woods are often chosen for their lack of taste and odor. Butter tubs, cutting boards and kitchen utensils are made of fir, spruce, maple, beech and basswood for this reason.
DENSITY AND SPECIFIC GRAVITY Specific gravity measures the relative amount of cell wall material, and is an excellent index for predicting the strength of wood. It is expressed as the ratio of the density of a material compared to the density of water at 39°F (4°C), or:
The moisture content of the wood must always be specified, because the wetter the wood, the larger its volume and the more water it will displace. Figure 1-8 lists the specific gravity of common native woods at 12 percent moisture content (air dry).
Fig. 1-8.Source: U.S. Forest Products Laboratory, Wood Handbook: Wood as an Engineering Material,U.S.D.A. Handbook No. 72.
Water has a specific gravity of 1.0, whereas pure wood material (with no cell cavities) would have a specific gravity of 1.54, about 50 percent higher than water. All wood has cell cavities filled with air, water or extractives. Live oak has the highest specific gravity (.88, at 12 percent moisture content) of any North American wood, while Northern white cedar has the lowest at about .31.
Density is defined as mass per unit volume, and is usually expressed as pounds/cubic foot (lb/ ft3), or grams per cubic centimeter (g/cc). Density also varies with the moisture content of wood. Water weighs 62.4 lb/ft3 or 1g/cc. Wood with a specific gravity of .50 would have a density of 31.2 lb/ft3, or .5g/cc. A cubic foot of solid wood material (with no cell cavities) at 0% moisture content, having a specific gravity of 1.54 would weigh 96.1 lb/ft3, or 1.54 g/cc. Density is a good general indicator of hardness and the amount of shrinkage and swelling to be expected for a given species. As a rule of thumb, the denser the wood, the more movement can be expected.
Density is easy to approximate by floating a long, thin piece of wood upright in water. The ratio of the length below water to the total length, times the weight of water per cubic foot equals the density at that specific moisture content. For example a 14″ (35.5 cm) is floated upright, and 8.5″ (21.6 cm) is below the waterline, then
GRAIN AND FIGURE A knowledge of the basic makeup of wood helps in the understanding of grain structure. Grain is simply the alignment of the wood cells. The term is used in describing the arrangement, direction, size and appearance of the fibers, vessels and rays. Strictly speaking, figure is the appearance of the grain as it is exposed on the surface of a board. In the lumber industry figured wood refers to certain types of irregular grain patterns. By simply splitting a piece of wood, one can determine whether the grain is straight or wavy. Grain around branches, roots and crotches will be wild, wavy and extremely unpredictable and difficult to work.
In some trees the grain does not grow perfectly up and down, but tends to spiral around the trunk. Spiral growth is present to some extent in both hard and softwoods, but unless the spiral is severe, it is considered normal. In some species the spiral reverses itself every few years, growing first clockwise, then counterclockwise. This interlocked grain is very difficult to split, chisel and plane. The grain goes in opposite directions and appears as fuzzy stripes (Fig. 1-9). Interlocking grain is found in elm, sycamore and black tupelo. Finished, it is sometimes known as ribbon grain.
Fig. 1-9. Interlocking grain looks fuzzy on sawn sycamore.
Wavy grain patterns are the result of longitudinal cell growth in waves, which gives a washboard appearance when the wood is split (Fig 1-10). This occurs most often in maples, birches, and, to some extent, in ash and cherry. In maple, when the waves are small and tightly spaced, the grain is called tiger-stripe or fiddleback. This abrupt oscillation of the grain is known as chatoyance, (from the French chatoyer, meaning to shimmer) and results in dark and light areas, depending on the direction of view. Chatoyance is not limited to figured wood. Even straight-grained door frames made from the same piece of wood will exhibit differences in color when the rails are turned 90° to the stiles.
Fig 1-10. Split tiger-stripe maple shows the undulating grain.
Very rarely, areas of interconnected ovals and grooves will result in blister, or quilted grain in maple. A more common figure is bird’s-eye (Fig. 1-11). This is the result of small indentations in the grain, more or less like dimples, usually evident under the inner bark. Because the cambium layer is the source of new growth, the bird’s-eye figure continues as each new ring is formed. Bird’s-eye varies in size and distribution. This figure is most common in rock, or sugar maple, but is sometimes found in ash and birch.
Fig, 1-11. Bird’s-eye maple.
There is as of yet no satisfactory explanation as to what causes blister, tiger-stripe or bird’s-eye figure. Suggestions such as climate, soil, stress, viruses or genetics have so far been discounted.
Crotch grain, or feathering around root and branch crotches, is caused by distortion of the grain and crowding and twisting of the annual growth. Crotch grain (Fig.1-12) is one of the most common figures encountered. It occurs frequently in walnut, ash, oak, birch, cherry and to some extent in all hardwoods.
Fig. 1-12. Feather or crotch figure in white ash.
Another specialized pattern is pigment figure. Actually, it is not a grain pattern, but rather streaks of color independent of the growth rings. Pigment figure is caused by uneven distribution of extractive deposits in the heartwood. An excess of dark deposits is most dramatic, but occasionally a lack of extractives may cause a lighter area in the heartwood known as false or included sapwood. Pigment figure is common in black walnut, Eastern red cedar and sweet gum, and is sometimes present in cherry and even pine.
It is, above all, succinct, easy to understand and perfectly suited for the furniture-maker. As important as what is in its 160 pages is what is not. It’s not a detailed analysis of cell growth. It is not a heap of tables and equations for figuring truss loads in residential construction. It is decidedly not a scientist’s approach to the material.
Instead, “With the Grain” contains the facts you need to know at the lumberyard, in the woodlot and in the shop. It gives you enough science so you understand how trees grow. It explains the handful of formulas you have to know as a furniture-maker. And it gives you a hearty dose of specific information about North American species that will inspire you. Becksvoort encourages you to use the trees in your neighborhood and makes the case that just because you cannot find catalpa at the lumberyard doesn’t mean it’s not a good furniture wood.
You’ll learn to identify the trees around you from their silhouette, leaves and shoots. And you’ll learn about how these species work in the shop – both their advantages and pitfalls.
Becksvoort then takes you into a detailed discussion of how wood reacts to it environment – the heart of the book. You’ll learn how to calculate and accommodate wood movement with confidence and precision. And you’ll learn how to design furniture assemblies – casework, drawers, doors and moulding – so they will move with the seasons without cracking.
Wood Structure Wood, or xylem, is the cellular material that makes up the bulk of the tree. It consists mainly of dead, hollow cells. Chemically, wood is composed of 40-50 percent cellulose, 20-35 percent hemicellulose, and 15-30 percent lignin. Cellulose is a very long, complex molecular chain, which, when broken down, yields the simple sugar glucose. Hemicellulose, closely associated with cellulose, is composed of shorter molecular chains of several types of sugar. Lignin is an intercellular material that bonds the wood fibers together. Aside from these three major components, various extractives are also present in the wood. Although not part of the wood structure, the extractives are usually found mostly in the cell walls, and contribute to the wood’s characteristic color, odor, taste, decay resistance and flammability. These secondary ingredients include oils, tannins, waxes, gums, starches, alkaloids, color materials and about 1-2 percent ash-forming minerals such as calcium and silica.
Figure 1-1 shows a typical cross section of a hardwood stem. (A) is the cambium layer, only a few cell layers thick, which produces the bark (phloem) toward the outside of the tree, and wood (xylem) toward the inside of the tree. Cambium extends in a continuous layer between the wood and bark, and gives rise to the tree’s lateral growth. In the temperate zones, during the course of one growing season, one new ring of wood is added to the trunk, roots and branches. Wood formed the previous year does not continue to grow. The width of the growth rings is not necessarily consistent in size, even within a species. Ash, for example, when grown in an area of little rainfall and poor soil, may have up to 40 rings per inch (2.5 cm), slow growth, while the same species grown in an area of abundant moisture and nutrients may have only 4 or 5 rings per inch, or fast growth. Slow versus fast growth also depends on competition from neighboring trees. (B) is the newly formed inner bark, a soft, fibrous material that carries food down from the leaves to all parts of the tree. During the growing season, the cambium layer and the inner bark are very soft and fragile. This means that logs cut during the spring and summer will have easily peeled bark, whereas those cut during the late fall and winter will usually retain their bark. (C) is the dead, corky, outer bark. As the diameter of the tree increases year by year, the bark becomes thicker and begins to crack. With age it usually becomes quite thick and furrowed (except in trees like beech and birch), and begins to slough off from the action of wind and weather.
The newly formed wood is the sapwood (D). It constitutes from one or two to more than 200 years growth (in some conifers), depending on the species (Fig. 1-2). Sapwood functions primarily to conduct water and minerals from the roots to the leaves. Most of the newly formed cells die in a short time. A few, the parenchyma cells, retain their protoplasm in the cell cavity and act as living food-storage cells. After a number of years, the sapwood loses its function and turns to heartwood (Fig. 1-1 E). The last of the parenchyma cells die, leaving only the cell walls that give the tree structural support. Extractives are deposited in the heartwood cells, giving the wood its distinctive color and other properties. Sapwood, having no extractives (some of which are toxic to fungi), is not as decay-resistant as heartwood, and should not be used under conditions conducive to decay. The extractives present in the heartwood of some species add to the mass of the cells, and increase the density of the wood somewhat.
Fig. 1-2. Number of Annual Rings in the Sapwood of Common Hardwoods. Source: Charles Sprague Sargent, Manual of the Trees of North America
The pith is located in the center of the tree (Fig. 1-1 F). This is a soft, sometimes spongy material formed behind the apical meristem. In most species it is only slightly visible as a darker tube. In some trees such as black walnut (Fig. 1-3), butternut and sumac, the pith is quite pronounced. Surrounding the pith is an indistinct area known as juvenile, or pith wood, characterized by wide growth rings (especially in conifers), low density and strength, and greater longitudinal shrinkage.
Radiating from the pith outward are the rays (Fig. 1-1 G). They extend to the cambium and are used in lateral transport of nutrients through the sapwood. Rays tend to bind the wood, thereby reducing the radial dimensional change.
Fig. 1-3. Pith in Black Walnut
Trees grown in temperate climates have a cycle of growth and dormancy that results in the appearance of annual rings. Typically, each spring as growth resumes, the cambial layer produces an abundance of large, thin-walled cells. Spring is a time of mild temperatures, maximum daylight and ample rainfall. Consequently, cell growth is quick and profuse. This initial growth is known as early-wood, or spring-wood. As the season progresses and day length decreases, the weather gets hotter and drier and growth slows. Cell formations become smaller and thicker-walled. These are the late-wood cells. Finally, during autumn growth stops for the season. Because the late-wood cells have thicker walls that portion of the growth ring is more dense. This is most apparent in old, weathered wood, which takes on a ridged appearance as the early-wood erodes faster than the dense late-wood.
Some tropical woods have no apparent growth rings. In areas where the weather is constant yearround, growth continues uninterrupted.
Classification of Trees Botanically, trees are divided into two classes: gymnosperms and angiosperms. Commercially, woods are divided into softwoods and hardwoods, softwoods referring to the gymnosperms and hardwoods referring to the angiosperms. These terms should not be taken literally, because not all softwoods are soft (yellow pine is about as hard as black walnut), nor are all hardwoods hard (basswood, and cottonwood are quite soft). Because these terms will continue to be used in the trade, the knowledgeable woodworker should recognize that they are used merely to distinguish the two groups, not define them.
Gymnosperms, characterized by exposed seeds, are the older of the two groups, and include all the conifers and even gingko (commonly thought of as a hardwood because of its broad, deciduous leaves). Conifers are characterized by their single, straight trunk and needle-shaped leaves, which are retained all year (except for cypresses and larches). Needles, usually smaller than leaves, have a waxlike coating that prevents water loss during long periods of dormancy. Thus adapted, the conifers are the dominant trees in the northern forest.
Coniferous wood is fairly simple (primitive) in structure. It is composed predominantly (roughly 90 percent) of all-purpose tracheid cells, which are long, thin and hollow. Although the cells are closed at both ends, liquids pass from one cell to the next through “pits” in the cell walls. Conifers also contain medullary rays. Some of the conifers also contain resin canals, which are large (visible), tubular passages that exude resin, or pitch. These canals occur in the species of pine (Pinus), larch (Larix), spruce (Picea) and Douglas fir (Pseudotsuga). Conifers lack specialized vessels or pores. The entire group is classified as having nonporous wood.
On a cellular level, the angiosperms are more specialized than the gymnosperms. They contain more ray cells (from 6 percent to 31 percent by volume), and only about 25 percent of the wood consists of fibers. These, like the tracheids in conifers, are long, thin cells with thick walls that give the tree support. From 6 percent to 55 percent of the wood is composed of vessels, or tubular openended cells. They have thin walls and large diameters, specifically made for the conduction of sap. When the vessels are exposed by cutting, they are called pores. Wood with large vessels such as oak, ash or chestnut are said to be open-pored, or opengrained. When exposed on any surface, these vessels are readily visible by eye or with a hand lens, and can be felt by a fingernail across what appears to be a smooth surface. Because vessel sizes vary widely among species, designation such as open- or close-grain are relative. What is more important is the arrangement of the vessels in the growth rings.
When large vessels (pores) are formed primarily in the early-wood, the wood is called ring-porous. The vessels form a distinct band in the early-wood (Fig. 1-4). Vessels, although present in the late-wood, are much smaller and fewer. Ring-porous woods include ash, hickory, oaks, chestnut, elm, sassafras and locust.
At the other extreme are the woods that are diffuse porous (Fig.1-5), those with pores scattered evenly throughout the year’s growth. The pores are all about equal in size, so the early-wood and late-wood are therefore indistinct. Maple, birch, dogwood, beech, holly, poplar, magnolia, hornbeam, sycamore, willow and basswood are all diffuse-porous.
Between these two distinct groups are the semi-ring porous (or semi-diffuse porous) woods (Fig. 1-6). The main characteristic of these woods is a gradual change from large vessels in the earlywood to smaller vessels in the late-wood. Species that have semi-ring porous wood include catalpa, persimmon and plum. Certain species of hickory, walnut, oak and willow are sometimes included in this group.
The pores of exposed end-grain heartwood will sometimes appear clogged with a frothy, film-like substance called tyloses. Tyloses is formed in some species when the sapwood turns to heartwood. In woods such as red oak, cherry, maple, dogwood and honeylocust tlyloses is insignificant or totally absent. In others such as white oak, tyloses development is quite extensive, while in Osage orange and black locust, the vessels are tightly filled.
With the finishing complete, the appearance of wear is believable along the seat, sticks and comb.
The following is excerpted from John Porritt’s “The Belligerent Finisher.” This shows the first two steps (surface preparation and adding color) before he goes on to burnish, stain, paint, shellac, oil, dent, wax, and add the finishing touches. It sounds overwhelming but the process is such an incredible transformation that you can’t help but to want to give it a try.
Porritt, who works from a small red barn in upstate New York, has been at his trade for many decades, and his eye for color and patina is outstanding. We’ve seen many examples of his work, and it is impressive because you cannot tell that any repair or restoration has been done.
His techniques are simple and use (mostly) everyday objects and chemicals – a pot scrubber, a deer antler, vinegar and tea. How you apply these tools – with a wee bit of belligerence – is what’s important.
The book is lavishly illustrated with color photos that clearly explain the process. With the help of this book, you’ll be able to fool at least some of the people some of the time with your own “aged” finishes.
While similar to its cousin behind it, this chair features a square-cornered seat and a backrest that is straight. Soon, many of these crisp lines will be eased by burnishing.
This second side chair is made of oak. The seat is white oak and the rest of its parts are red oak. Because I built this chair using American species, the grain is quite straight and regular. With Welsh stick chairs and other vernacular forms, the wood is often quite gnarly. So my goal with this chair is to add quite a bit of texture to make the chair more interesting.
To help the chair look more like an old survivor, I used young, small-diameter trees. These were available to me after the workers came through. Now they’re all using wood chippers, which is most unfortunate – certainly for me. The grain of these small trees has more character than large-diameter trees with long-straight trunks.
In addition to the texture, I want the chair to have a nice chestnut brown color to the wood that looks like it has been covered in green paint – a common color on old chairs. In the areas where the sitter would rub against the seat, the green paint will be worn through. Plus, like all chairs that have had a long and interesting life, this chair will have lots of burnished surfaces.
Just like with the first chair, this chair was finished straight from the tools – no sandpaper. Plus the tenons and any pegs have been left a little proud, which makes them easy to burnish.
Give the piece a good soaking with water to raise the grain and soften the wood a bit.
Surface Preparation. I begin this process by giving the chair a good soaking with water, which will raise the grain and soften it. I immediately follow that with the nylon brush, which is chucked into an electric drill. This is the first step to adding texture, as the nylon bristles wear away some of the softer earlywood in the oak.
You could probably get the same effect with a wire brush. As you go over your chair, spend more time brushing the areas that would contact the sitter, including the seat, sticks, backrest and the leg ends.
The nylon brush adds texture to the piece by gently wearing away some of the softer earlywood. Focus your efforts on the areas that contact the sitter.
It may seem strange to hear about using the nylon wheel brush to take out the soft earlywood and then burnish it to get a surface skin. The thing with old surfaces is they have undulations. Sometimes these are like a fine ripple, a movement to the surface where the wood has shrunk, expanded with moisture, or been abraded by time so that there are ridges and troughs. It’s not a surface straight from a cutting tool, so the brush action gets movement intothe wood and the burnishing pulls it over to consolidate it. A good, used, worn surface that reflects light in an uneven fashion.
Sample sticks are a roadmap for your finishing process and show you how the different colors and chemicals will interact. It can be helpful to label each sample.
Add Color. Before I start adding color to a piece, I’ll make sample sticks using scraps from the project itself. This prevents unwanted surprises.
The first coloring step requires us to first add tannin to the wood. Then we’ll add a solution made with vinegar and steel wool, which reacts with the tannins to give a nice, aged color to the wood.
Add tannins to the wood by brushing on a solution of black tea mixed with household ammonia.
To make the tannic solution, first make a batch of strong, black tea that you steep overnight (do not add milk or sugar). With the tea at room temperature, add some household ammonia – the final mixture should be about 10 percent ammonia and 90 percent tea. (Use ammonia without added soap.)
The ammonia seems to help drive the tannins into the wood.
Once the mixture is applied, I follow that by going over all the surfaces with a heat gun. The heat gun raises the grain and speeds the process along. If you aren’t in a hurry, you can let the tea flash off on its own.
The vinegar and iron solution should turn the wood a blackish color. If no color appears – or it is weak – use a stronger solution.
Now it’s time to add the color. The solution is made by dissolving a pad of oil-free steel wool in a jar of household white vinegar. I make mine in a large lidded jar. It usually takes three days to a week for the metal to dissolve. I also like to make batches in different strengths. You can make a stronger color by adding more steel wool to the solution.
I brush the solution on with a chip brush. If the wood does not quickly turn a brown/black, you should use a stronger solution. Set the chair aside and allow the solution to dry.
