One of the (many) barriers to making staked furniture or chairs is wrapping your head around the compound-angle geometry. And then figuring out how to execute it at the bench.
The new Crucible Chairpanzee ($16 plus shipping) does the trigonometry for you, allowing you to translate rake and splay into sightlines (which create your layout lines) and resultant angles (which is the setting of your sliding bevel).
This allows you to easily design new pieces of furniture with compound angles and to replicate angles from existing pieces of furniture from photos.
The Chairpanzee is a clever sliding calculator that is printed and assembled in the United States. Here’s how we use the Chairpanzee on a chair design (though it can be used for tables, stools or any other piece of staked furniture).
To calculate the “sightline:”
1. On the underside of the seat, draw a line connecting the two front leg mortises (as shown above). This is the baseline.
2. Move the calculator’s slider to the desired splay angle in the top window.
3. Next to the lower window, select the desired rake angle. The number shown in the adjacent window is the sightline angle.
4. Draw the sightline angle on the underside of the seat using a protractor. The 0° on the protractor should be directly on your baseline.
5. Repeat steps 1 through 4 for the rear legs.
To calculate the “resultant:”
6. Confirm that the calculator’s slider is set to the desired splay angle in the top window.
7. Next to the lower window, select the desired rake angle. The number shown in the adjacent window is the resultant angle.
8. Set your sliding bevel tool to the resultant angle and place it directly on the sightline on the underside of the seat.
9. Drill your mortise. Keep the drill bit perfectly parallel to the blade of the sliding bevel.
The Chairpanzee is available for immediate shipment. We hope that some of our retailers will also carry this product for our international customers.
In the coming week I’ll post a video that shows how it’s used.
“Make a Joint Stool from a Tree” was a first on several fronts for Lost Art Press. It was the first book in full color, the first to use a larger format and the first to have a dust jacket.
It was also the first “edition” book Chris designed, with the guidance of Wesley Tanner (who would later design the award-winning Roubo books for Lost Art Press). That’s who introduced Chris to the venerable book designer’s bible: “Methods of Book Design,” by Hugh Williamson (1956).
It took so long…they were working on it for more than 15 years (most of that prior to signing on with Lost Art Press). A fun drinking game: Every time Peter’s outfit has changed in the pictures, take a shot. (On second thought, that’s not such a good idea…). You can also watch Peter and JA age and change throughout the pages.
Fig. 7.2 Clockwise from the left, these pigments are: bone black, iron oxide and yellow ochre. A little goes a long way, especially with the red. Store them in a dry place and they’ll last a long time.
Now that the stool is all assembled and trimmed, it’s time to apply a finish. At this stage, you can use your favorite finish, but if you would like to explore period-style work further, then oil-based paint is an excellent choice for a period finish. This is attainable, but with some cautions.
Surviving artifacts sometimes have remnants of their original painted finish, and these can be analyzed and the pigments and vehicles identified.
This analysis is rarely applied to “clear” finishes; it usually centers on surviving colors appearing on period works. We have benefited from colleagues who have shared with us the findings of their studies, but there is still a long way to go in this aspect of 17th-century furniture studies.
Fig. 7.3 Another ingredient in period paints was calcium carbonate. It was used as a filler to extend the paints’ covering abilities. A good easy source for small quantities is blackboard chalk. Break it up with a hammer into the smallest bits you can, then mix it in with your pigments.
Paint consists mainly of a color, the pigment, that is dissolved in a medium. In many cases the medium is a plant or nut oil, such as linseed oil (from the flax plant) or walnut oil. It is often thinned with turpentine. One aspect of period paints that is best avoided today is the use of lead as an ingredient. The lead served to dry the oil, and in its stead you can add just a few drops of Japan drier, which will help the linseed oil dry a little more quickly. A little umber pigment mixed in with your other colors will also help with drying; usually it’s too small of an amount to affect the color much.
Fig. 7.4 There’s no way around it – paint-making is messy. A dropcloth on the bench is a good idea. If you have a small piece of glass such as this one, you can scrape your mixed paint into a shallow dish as you go, them mix more to add to it.
For our stools, we paint them with homemade paints made by grinding dry mineral pigments in oil, or an oil/varnish combination. The available colors are usually earth colors – reds, yellows, browns – and carbon pigments – lampblack or bone black. Artists’ supply outfits are a good source for dry pigments. Use their linseed oil also; it is better quality than the boiled linseed oil from the hardware store.
Red is the standard color based on what little evidence we have seen from studying period pieces. We use iron oxide pigment. It goes by various names: iron oxide, Indian red, Venetian red or red ochre. The best tools for mixing the paint are a muller and a piece of plate glass. The muller is essentially a flat-bottomed pestle made of glass. Like many good tools, they are expensive. You might try your first batches of paint by grinding with a mortar and pestle, or even just a palette knife on glass. Then if you plan on going further, you’ll want the muller and glass.
Fig. 7.5 If you decide that mixing paint is for you, then eventually you’ll want a muller such as this. A mortar and pestle works, but it’s harder to get paint out of a mortar than off a flat piece of glass.
Make a ring of pigment, and pour in some of the medium. Slowly mix the medium and pigment together with a palette knife, then take the muller and work in a circular motion to dissolve the pigment in the medium. Mix up enough to paint your whole stool; you don’t want to stop during the painting to mix up more paint.
Use a clean, soft, natural-bristle brush to paint the stool. Period brushes were round; the most common modern ones are flat. If you want to try round ones, get them from an art supply store rather than a hardware store. Thin paint will have a better chance at drying than thicker, more opaque paints. Several coats will result in a more solid color and finish. You can combine the red and black in a contrasting application, using the black for the mouldings, or even pick out aspects of the turned decoration in alternating red and black.
Warning: Linseed oil generates heat as it dries. This can cause spontaneous combustion of rags and brushes and any other absorbent materials that have come in contact with the oil. After use, put all such materials outside to dry in a well-ventilated place for at least 24 hours in a temperature of not less than 40° Fahrenheit. Or you can thoroughly wash all contacted materials with water and detergent and rinse.
Fig. 7.6 Iron oxide reds can vary from place to place. Some are brick-red, some are brighter. You can also mix pigments together, add some yellow ochre to iron oxide to add some variety to your colors. Vermillion is a very bright red, so use it as an accent color.
Recent research at Winterthur Museum and the Museum of Fine Arts, Boston, has identified examples of 17th-century paint made with pigments mixed in thin solutions of hide glue instead of oil. To do this yourself, prepare the glue granules just as you would for using adhesive, but with more water. Fill the bottom of a glass jar with the glue granules, add enough water to cover them plus a little more, and let it soak overnight. When you’re ready to make paint, heat the glue mixture slowly. If you don’t have a dedicated glue pot, you can put the glue in a glass jar sitting in a few inches of water in a pot. Stir regularly. Keep the mixture thin. When the glue is nice and thin, turn off the heat, and you’re ready to mix the paint.
Just as with the oil, start by sifting some pigment onto your plate glass, or in a mortar. Then pour some glue in and start mixing them. Keep adjusting by adding pigment and glue until you reach the solution you’re after. Painting a whole stool with this paint is tricky; the glue thickens as it cools. It requires a little tinkering, so add water if it thickens, and return the glue to the heat from time to time as well. This protein paint needs a finish over it, or it can rub off. The research indicates a plant-resin varnish as a top coat.
Editor’s Note: Apologies if you received this post twice. We had some technical problems with this entry (our fault and not Nancy’s).
In her profile on the Brigham and Women’s residency alumni web page, Dr. Ouida Vincent had some fun with the pro forma question “DO YOU HAVE A FAVORITE MEMORY FROM RESIDENCY?”
“Spending the night out with co-residents at the ’70s disco,” she answered, punctuating her response with a single word: “Polyester.”
This disarming response will come as no surprise to those who know Ouida, whether in person or from Instagram, where her warmth, humor and sense of adventure are on regular display. “Headed to Handworks by way of MSP,” she wrote in May 2017. “Please say hello… I’ll be the BWWDL” – as she’d previously described herself, the “BLACK WOMAN WITH DREAD LOCKS” – because (let’s be real) how many Black women (or men) with dreads would you typically expect see at a gathering of hand-tool woodworkers in rural Iowa?
With her Dutch tool chest in her shop.
When we spoke, on a crisp Saturday morning this fall, she’d just returned from delivering sourdough cinnamon rolls to her mother. It was a short walk up the hill by her house; she was still in her pajamas, under a Carhartt jacket.
Along with thousands of others, Ouida (pronounced WEE-da) took up sourdough bread baking in April, when the pandemic prompted so many to plunge themselves into baking that stores could not keep yeast on the shelves. It wasn’t her first experience with baking; at Cornell she did a medical school rotation on the Navajo Reservation in 1989, staying with a family who baked wholewheat bread or cookies every day. Inspired by their example, she took up baking herself when she returned to med school. Although her first few loaves were “like hubcaps,” she kept at it and quickly improved. She baked every weekend until her professional work became too demanding.
Ouida approaches sourdough baking with the analytical rigor of a scientist and the enthusiasm of one who bakes for love, not money. Her Instagram feed is full of boules and batards – some whole, some sliced in half to reveal herbs, olives or “crumb.” An early September entry that shows the kind of springy texture I can only dream of producing reads like notes on an undergraduate’s experiment:
“[W]hen I want to check oven spring, I look at how the holes are oriented and if the entire loaf from bottom to top was involved in ‘spring.’ You can get three patterns[:] no spring (dense loaf) that may or may not have risen any, spring primarily on the outside of the loaf with a dense (yet hopefully done) interior and spring that involves the whole loaf. The holes will be elongated in the direction of spring and will glisten.”
Note the measurements. Clearly the work of a scientist.
She brings the same studious curiosity to woodworking. Ouida sees a piece of furniture she likes and figures out how to build it. Her office and home are furnished with pieces of her own making. And when she decided a proofing box would be a boon to her sourdough baking, she puzzled out what it would take to fabricate one.
Ouida’s proofing box with a loaf in progress.
These days, Ouida, whose day job is clinical director of a hospital on the Navajo Reservation, is “in a mask 10 hours a day, five days a week.” Anyone who pays attention to national events will be aware that Native Americans have been affected terribly by Covid-19. Ouida adds, “Even when there is a vaccine, I will wear my mask (even after getting the vaccine). This is about public health.”
Ouida was born in Nashville, Tenn., the fourth of five children. When her mother and father married, her father brought three from a previous marriage and her mother brought her; they had one son together. Her name is common in the South. “My mother told me that she heard the name and wanted me to be remembered, so she gave me the name.” Then comes the zinger: “You can imagine what kids and substitute teachers did with [it].”
Ouida and her little brother.
She can’t remember a time when she wasn’t fascinated by making things and figuring out how to fix them. Her older brother David was “a real Mr. Fix It” from the start, Ouida says; she followed him around and learned from his example.
After her parents split when Ouida was 10, her mother moved Ouida and her younger brother from one place to another, wherever she could find work, usually in college financial aid offices. Ouida would have signed up for shop class in school, but as a girl born in 1963 she wasn’t allowed to. That changed when her family moved to Virginia Beach, Va., in 1976; she enrolled in shop class and small engine repair. She and her classmates learned to strip down and rebuild two-stroke and four-stroke engines, restoring them to working order; they also had to frame the corner of a house, complete with functioning plumbing and electrical service.
When they moved to Alabama in 1979, Ouida found herself barred from shop class once again. Undeterred, she decided to go ahead and build things on her own, though she found that was more easily said than done, with few tools and no shop. While working on a body for an electric guitar she asked the shop teacher at school if she could use the band saw. He asked her to prove she knew how – a challenge she met in short order. He gave her permission to use the shop facilities when classes weren’t in session. She’s been building ever since.
Given her facility for learning new skills and diagnosing problems, it’s not terribly surprising that Ouida, who excelled academically, found her way into medicine. She graduated from Cornell Medical College in 1990 at the age of 27, then did a residency at Brigham and Women’s in Boston. “My uncle was an Ob/Gyn. It was really the first medical career I was exposed to. I was briefly attracted to general surgery, but the general surgeons I was exposed to seemed not to have personal lives. I was ultimately attracted to the combination of surgery and diagnostic medicine that obstetrics and gynecology offers.”
She originally hoped to do a medical student rotation in Alaska, but when she inquired, she learned that all rotations there were filled – she would have had to apply at least a year in advance, rather than a few months ahead of the starting date. “When I walked in to talk with one of our deans, she was opening a letter from alumni who had taken jobs in Shiprock, N.M. They had space for students, so I went. The year was 1989. I fell in love with the medical community and knew I wanted to return,” though she adds “I didn’t plan on making a career out of it.”
In 1998 she moved to Gallup, N.M., and became Chief of Obstetrics and Gynecology. When her real estate agent heard about her interest in woodworking, she mentioned there were classes at the local branch of the University of New Mexico. Ouida signed up for a course in cabinetmaking. The college had a well-equipped machine shop, but no hand tools. As she deepened her experience of working with machines, she learned another valuable lesson – “the frustration of power tools!” Even though the college had a full-time staff person charged with repair and maintenance, “there was always a machine down.”
Ouida’s work responsibilities grew, leaving her with less time for classes, yet she continued to pack in as much woodworking as she could. One of her early projects was an 8’-high x 3’-wide media cabinet. Another was a hutch based on an article in Fine Woodworking; it’s in her office today.
In 2006 she bought a property in Colorado, attracted in part by a dilapidated barn on the site. “This is my woodshop,” she remembers thinking when she first saw it. Termites and rain had done their worst; contractors she called for estimates to rehabilitate the structure said it wasn’t worth saving, that she should build something new. “But I wanted to work in a barn,” she says. Eventually she found a contractor who was willing to fix it up for her.
The barn shop at dusk.
Ouida slowly taught herself to use hand tools. She learned a lot from Chris Schwarz’s videos on hand tool basics and watched the Popular Woodworking series “I Can Do That.” She made a desk of ambrosia maple and cherry for a friend; the hand-cut dovetails were “so gappy that I made the gaps the same size and backfilled them with filler of a different color.” She persevered and improved. The same went for sharpening. “The first time I sharpened a plane blade it took six hours,” she says. But she found the more she worked in hardwoods, the greater her appreciation of the need for sharpening and the better at it she became. In the end, she says, “the wood became my best teacher.”
Around 2011 she made some shop stools based on a video by Mike Siemsen. When “The Anarchist’s Design Book” was published, she built one project after another from it – a boarded bookcase, staked desk (now in her office), six-board chest and staked chair. “I would have made more from that book,” she says, “had Peter Follansbee not published his book and completely derailed my life! I’ve literally done nothing but carve since 2019.”
Evidence of obsession.
Ouida is well aware of the sacrifices her mother made as a single parent. She also deeply appreciates her maternal grandmother’s support, calling her “a constant figure in my life until she passed away in 2001.” She cites one incident in particular, which culminated in the United States Supreme Court case NAACP v. Claiborne Hardware, to illustrate the impression her grandmother Dolly made.
Dolly Thompson was from Mississippi and had a ninth-grade education. “It was in the Jim Crow South,” Ouida points out by way of context. Even though the population of Claiborne County, where they lived, was majority Black, all the political seats were held by White people. Her grandparents owned a funeral home and were solidly middle-class. But when they traveled cross-country to attend mortuary conventions, they always had to think about where they’d be allowed to stay at night.
It was common in that time and place for Black people to be called names (if their presence was even acknowledged) and forbidden to use public restrooms or sit at lunch counters. Tired of being treated as second-class citizens when they were upstanding members of the community, Ouida’s grandmother (her grandfather died in 1962) and many of her fellow community members, working with a local chapter of the National Association for the Advancement of Colored People (NAACP), decided to “talk with their dollars.” They organized a boycott of White-owned businesses, setting up a supply house of their own called Our Mart to keep fellow citizens supplied with hardware, food, clothes and other everyday needs. They funded the project by selling shares.
Ouida’s maternal grandmother, Dolly Thompson.
Several of the White-owned businesses joined forces and sued for damages – in a majority-Black county, their businesses couldn’t survive without the now-missing income. When the Mississippi Supreme Court ruled in the White businesses’ favor, Ouida’s grandmother and her fellow boycotters took the case all the way to the United States Supreme Court, which ruled in favor of the NAACP.
The whole thing, she notes, came about “simply because that group of people wanted better treatment.” Although this was her grandparents’ experience, Ouida understands it’s not that far removed from our own time — she belongs to the first generation to grow up outside of Jim Crow. And it’s easy to see how Ouida, with these determined and hardworking role models, became the kind of woodworker who doesn’t flinch at challenges, but sticks at a task until she has mastered it, having lots of fun along the way.
Summing up our conversation, she reflects that “the reason I’ve continued doing [woodworking] is the stimulation it provides.” She trained as a surgeon, but her work for the past several years has been in administration. She misses the contact with tools and materials. Bread making helps fill the gap; woodworking goes even further. “Now I get to hold instruments in my hand that use fine motor skills., similar to using a scalpel,” she adds. No wonder she can’t stop carving.
James Krenov presents his “Oak Parquetry” cabinet from 1997 to the class at The College of the Redwoods Fine Woodworking Program (now The Krenov School). Photo by David Welter.
The process of writing “James Krenov: Leave Fingerprints” has left me with a few qualifications: I’m happy to sit before an audience and talk about his roots and aesthetic history, or work with The Krenov Foundation to design and present a centennial exhibition (more on that in a bit). But, a question that I get asked frequently that I don’t feel 100 percent qualified to answer is: which is your favorite piece of James Krenov’s?
It’s a hard question, perhaps made complicated by my years of research – I could’ve rattled off a favorite cabinet or two with ease before I knew his full body of work. Furthermore, divorcing his life from his work is impossible. There are pieces I love because of their context, but are not his most technical or aesthetically pleasing works. And, frankly, this question asks my opinion, which I’ve tried not to exercise too much during the journalistic pursuit of writing his biography! But, I thought I’d share three pieces here that, after all my work, I find particularly appealing.
All of these pieces, and a couple dozen more, can be found in the gallery of Krenov’s work at the back of biography. And, if you want to join in the game of browsing his work and picking favorites, you can find a huge body of his work on The Krenov Archive, and share them in the comments below!
Cabinet of Andaman Padauk (1979)
1979’s “Cabinet of Andaman Padauk,” pictured in Krenov’s fourth book, “Worker in Wood,” pages 16-23. Photo by Bengt Carlén.
If you held my feet to the fire and asked me what I thought best summarized Krenov’s technical and aesthetic body of work, it would be this cabinet. Made in Andaman padauk, a wood that Krenov spent many words praising, with drawer-fronts of pearwood and Lebanon cedar drawer interiors, this piece’s form, wood composition and technical execution put it high on a list of “classic Krenovian” cabinets.
The graceful curves are emblematic of Krenov’s work toward the end of his time in Sweden, as are the floating door panels, which lift nicely away from the frame in which they’re suspended. The cove between the stand and cabinet carcase is nicely faceted, showing his penchant for gouge and knife carving. And, his use of the lighter padauk in the panels, which came from the same planks as the darker surrounding padauk used in the stand and carcase body, is a deft illustration of his careful choice of woods. If I were assigning a county-fair-esque superlative, this might come in at “Best Overall.”
Lower curved details of the padauk cabinet’s stand. Photo by Bengt Carlén.
The pearwood drawer drawer fronts and curved panel of the padauk cabinet. Photo by Bengt Carlén.
Fossil Cabinet (1993)
Krenov’s “Fossil Cabinet” in kwila, spalted olive and hickory from 1993. Photo by David Welter.
If the “Cabinet of Andaman Padauk” is “Best Overall,” this cabinet might be something like the dark horse of Krenov’s oeuvre. Made in 1993, a dozen years after his resettlement from Sweden to the school in California, this piece came in the midst of a flurry of cabinets that played with parquetry and veneer composition. Its unusual use of spalted olive veneers, inlaid into the veneered kwila carcase, make it singular in Krenov’s output. Throughout the 1990s, in his 70s, Krenov played with new ideas and forms, a fact that is missed by many historians, who consider his work to be relatively unchanged over his career.
Aside from the fact of its unique place among his work, this cabinet is also attractive in its proportions and shaping. By 2000, Krenov would focus his work almost entirely on small cabinets on tall, leggy stands, and this piece foreshadows that trend. The shaping in the stand is also quite appealing, and hearkens to the first joined stands Krenov made in the 1960s for his “Silver Chests.”
The interior of the “Fossil Cabinet,” showing the simple interior. Photo by David Welter.
Pearwood Drawer Cabinet (2002)
Krenov’s “Pearwood Drawer Cabinet” from 2002. Photo by David Welter.
This is the only piece of the three shown here that I’ve seen in person; in fact, it was the first piece of his I ever saw in the flesh, when David Welter (its owner and the long-time shop technician at The Krenov School) brought it to the school when I was a student. It’s graceful in just about every way; the carcase veneers are carefully arranged, without being loudly bookmatched or otherwise worried over, the legs sweep gracefully and the interior is full of asymmetric and sweetly pillowed drawer fronts.
This was the last piece Krenov made at the school; at the end of the school’s 20th year, Krenov retired at the age of 81. Not only is the cabinet impressive considering the maker was in his eighth decade, it shows his continuing evolution as a maker. Welter was quick to point out that the legs, albeit joined and arranged in a typical fashion to many of Krenov’s later cabinets, feature a shaping profile and style that was new to Krenov’s work.
The pearwood drawer cabinet’s interior, showing the asymmetric drawers and their satisfying pillowing. Photo by David Welter.
The legs of the pearwood drawer cabinet, showing the sweet shaping that was new to Krenov’s body of work. Photo by David Welter.
Before I sign off, I want to mention something that I’ll go into greater detail on next week. During the past three months, I’ve worked with Michelle Frederick, Kerry Marshall and Laura Mays in Fort Bragg, Calif., on an exhibition celebrating Krenov’s centennial, which is this coming Halloween. They’ve begun releasing short teaser videos that hint at the videos we’ve made for the exhibition on this Instagram feed. Next week, I’ll put up a post with insight into our process and what you can expect when the exhibition goes live on Oct. 31. But if you want to start getting excited, I encourage you to check out their Instagram.
A twisted Ligustrum sinense. This Chinese privet has the status of a Champion Tree in the U.K. It’s found at Thorp Perrow Arboretum, Bedale, North Yorkshire, and gained its Champion status through being the tallest and largest specimen in the country. In addition to these characteristics its status as a champion is surely derived from its most notable feature being the remarkably twisted trunk thought to be caused by a systemic fault.
I first learned about the Twin Oaks Community while working on “Cut & Dried” with Richard Jones. We needed an index. Members of Twin Oaks, an intentional community in rural central Virginia, make their living, in part, by indexing books. Additional income is generated by making hammocks and furniture and tofu, and seed growing. The Twin Oaks Community, comprised of about 90 adults and 15 children, are income-sharing. Members complete about 42 hours of business and domestic work a week, and in return receive housing, food, healthcare and personal spending money.
Rachel Nishan from Twin Oaks responded to my indexing query, and we agreed to work together. Indexing a technical book such as “Cut & Dried” is a rather monumental task, and just thinking about it made my eye twitch. Yet Rachel approached the project without an air of stress, asking detailed questions about tree types, specificity and British spellings. Throughout our correspondence one sentence has stayed with me, years later: “… a more technically-inclined reader could want to look through the index in a variety of different ways, so I have tried to be pretty redundant, which is the kindest for the user of the index.”
“Kindest for the user.” I think that’s the heart of bookmaking, no?
Richard and I sent hundreds of emails to each other while working together to turn his years of work into book form. And all of that correspondence, from image selection to epsilon size, was written with Rachel’s not-yet-said phrase in mind: kindest for the user.
I was nervous to begin work on this book. Honestly, I thought the content would be too technical for me to understand. But then I read it. And realized Richard used his genius to transform his scholarly work into easy reading. And Rachel made topics within the text easy to find. And Meghan designed the book to be easy on the eyes. All with kindness in mind.
Many woodworkers are initially reluctant to study trees in detail fearing the subject is dauntingly heavy. Whilst it’s true the subject can be studied with scientific precision it’s really only necessary to get to grips with the main elements to gain a firm basic knowledge. Wood isn’t created with the needs of the woodworker in mind. The creation of wood is necessary for trees’ survival. We simply use what nature provides. Understanding the original function of wood helps woodworkers use it sympathetically and successfully. One example of useful basic knowledge described earlier is to understand the essentials of Latin scientific classification resulting in precision and clarity in any discussion of the subject.
All trees are members of the plant family. Specifically, they are all spermatophytes meaning they are seed-bearing plants. Trees are generally characterised as being perennial seed-bearing vascular woody plants with a root system and (ordinarily) a single trunk supporting a crown of leaf-bearing branches. With exceptions (see mention of the Arctic willow, Salix arctica, earlier) they normally reach a minimum height at maturity of five m (15′) and survive for at least three years.
This basic classification then breaks trees down into two distinctive types – the angiosperms (covered seeds) and the gymnosperms (naked seeds). Alternative names for these two groups are hardwoods, deciduous or broad-leaved trees (angiosperms), and conifers or softwoods (gymnosperms). The terms hardwood and softwood can be misleading as not all hardwoods produce hard wood, e.g., soft balsa wood is the product of a hardwood tree whereas yew is hard and comes from a softwood tree.
Figure 3.1. Trees increase girth by adding growth rings annually. They increase in height by adding new growth at the tips of branches. Roots and root tips grow in the same manner.
Typical of deciduous trees in temperate climates is the loss of leaves during autumn as the tree loses vitality followed by a dormant winter period. As usual there are exceptions where many of the hollies (Ilex spp.) retain their spiky and waxy leaves throughout the year. Spring, with its longer daylight hours and warmer weather, heralds a new period of rapid growth with the emergence of new leaves, flowering and reproduction. This is not true of all hardwoods in all climates. Many equatorial living hardwoods are able to grow all year round and may never lose their leaves en masse. With these trees the cycle is continuous as old leaves reach the end of their useful life to be replaced by new ones.
Figure 3.2 . Dendritic (deliquescent) growth pattern of broad-leaved trees. The main trunk branches and rebranches.Figure 3.3. Excurrent form of coniferous Japanese larch. A single bole or trunk with subordinate branching. Larch is an exception to the rule because it loses its needles in winter. In this managed forest, juvenile Sitka spruce have established themselves between the planted larches. Dalby Forest, North Yorkshire, England.
Angiosperms (deciduous trees) from all climatic conditions have a characteristic growth pattern. Their form is deliquescent or dendritic, meaning there is branching and re-branching of a main trunk.
Gymnosperms (coniferous or evergreen) trees typically retain their leaves throughout the year, with larch being one exception to this trait. Their form is generally excurrent – the main trunk rises singly with lesser sideways branching. Broadleaved trees usually have large, relatively fragile, blade-like leaves and, to prevent dehydration of the tree resulting from their retention, they are lost before winter. Conifers on the other hand typically are able to resist dehydration because of their tough, needle-like waxy leaves, which stay on the tree through all the seasons. As with tropical hardwoods discussed earlier they lose leaves and replace them all year round. However, I’ve noticed even the much-despised fast growing leylandii (Cupressocyparis x leylandii) planted in my back garden by a previous owner loses more leaves in the winter than in the summer. Leylandii are, in truth, a very attractive tree grown where they have space. They grow very swiftly and are really too large in small British gardens – they rapidly exclude light and dominate these small spaces.
Figure 3.4. Scots pine (Pinus sylvestris). Needles (leaves) and seed cone. In common with broad-leaved trees conifers can be identified by a combination of factors – general form, bark, flowers, seeds and leaves. Scots pine needles, for example, occur in pairs, are bluish-green, twisted and about 50 mm (2″) long. They survive about four years before turning brown and dropping as a pair. Cones vary in size between 25 mm to 60 mm (1″ to 2-1/2″) in length and are usually rounded. The bark is distinctive being orange and flaky.
In common with hardwood trees living in cool temperate climates, evergreens have a dormant winter period.
Tree growth occurs in just three places. The first two are the tips of the branches and roots, which increases the tree’s height and the spread of the crown along with the range of the roots. The third place where growth occurs is in the girth of the trunk, branches and roots by the addition of an annual growth ring. Meristem or meristematic tissue refers to the growth tissue in trees. The growing tips of twigs and roots is the apical meristem. The lateral meristem is the cambium layer adding girth to the tree’s structure.
The cells produced by meristematic tissue, whether they are leaves, flowers, bark or wood, are largely of cellulose. Cellulose forms strong and stable long chain molecular structures. This, along with the lignin bonded with, or to it, is what gives wood its strength. Lignin is the “glue” holding wood together and is a complex mixture of polymers of phenolic acids. Lignin forms about 25 percent of wood’s composition and becomes elastic when heated. It is lignin’s flexible plastic property allowing wood cells to rearrange themselves that woodworkers use to their advantage during steam-bending wood into new shapes.
The majority of cells making up a tree’s structure are elongated longitudinal cells. Their long axis runs vertically up the trunk (and along the branches and roots). Some of these cells are short and stumpy and others are long and slender. The vascular function of the newly formed longitudinal cells is to conduct liquid raw essentials up the tree to the leaves and processed sugary food down the tree to nourish it. Spread through the wood are rays or medullary rays. These ray cells are also elongated but their long axis radiates from the centre of the tree toward the bark. They are stacked one upon the other throughout the length of the trunk in slender wavy bands.
In many wood species the rays are invisible to the naked eye but in others, such as numerous oaks and maples, they are usually highly visible because the groups of cells are large. Some ray cells – the parenchyma – store carbohydrates for use in cell development. The other primary purpose of the medullary rays is to transport nourishing sap toward the centre of the tree.
3.1 Log Cross Section From the outside there is the outer bark (see figure 3.6), which is a protective insulating layer against weather, animal, fungal and insect attack. The bark has millions of tiny pores called lenticels through which necessary oxygen passes into the inner living cells beneath. In polluted atmospheres such as cities the lenticels clog with dirt. London plane (Platanus x hispanica) is well suited to city life because it sheds its bark regularly, exposing clear lenticels. The bark of all trees flakes off as the girth gets bigger.
Figure 3.5. Medullary rays in European oak. On the left they are visible as light-coloured flaky patches – the sought-after quartersawn oak figuring or “silver grain.” To the right where the horizontal bands of end grain show the rays are visible as thin, light-coloured vertical lines. The centre of the living tree in this example is toward the bottom of the photograph.
Inside the outer bark is phloem, bast or inner bark. The phloem is produced by the cambium layer and is a soft spongy liquid-conducting vascular tissue that carries processed food – sugary sap – from the leaves to the rest of the tree.
Figure 3.6. End section view of small yew log. Identifying the most significant structures visible to the naked eye.
Beneath this layer is cambium – the lateral meristem (growing tissue) that adds girth to the tree. The cambium is a slimy layer only one cell thick. These cells divide constantly when the tree is active. The cambium produces not only phloem towards the outside but, towards the centre, it produces xylem.
Xylem has two major functions. As sapwood it conducts water and minerals from the roots to the leaves. Sapwood contains both live tissue and dead tissue. Dead xylem, the heartwood, is the trees’ structural support. The longitudinal cells described earlier are organised to form water- and nutrient-conducting tracheids in gymnosperms or conifers, although some hardwoods also contain tracheids. In angiosperms (broad-leaved trees) the order is different. Vessels, which are continuous tubular structures, form a pipeline from the root tips to the leaves rather akin to drinking straws bundled and glued together. (Note, though, the comment I made about some hardwoods also containing tracheids.) In oaks, for example (see figure 3.7), the naked eye easily picks out the initial spring-laid vessels or pores. In other tree types magnification is required. Sapwood is often attacked by food-seeking life forms such as fungi, insect and animal life.
As sapwood xylem ages it loses its vitality through the loss of the living protoplasm within the cells and turns into heartwood. In some species the transition between living xylem and heartwood is abrupt and clearly visible as seen in the yew cross section at left. With others it is hard to distinguish between sapwood and heartwood. The sapwood can remain as living protoplasmic cells for several years but this period varies from species to species, and even within trees of the same species. The yew sample at left shows newly laid sapwood that took about 8 or 12 years to convert to heartwood.
Figure 3.7. Close-up of European oak end grain showing light-coloured medullary rays and spongy, adsorbent, open-pored spring growth and denser less-porous late growth – European oak is a ring-porous hardwood.
Heartwood is the column of xylem supporting the tree. It is dead because it has lost its active protoplasm. Whilst outer layers of the tree are intact – protecting the heartwood nourished by foodstuffs transported to it by the medullary rays – it will not decay. Heartwood is usually, but not always, distinct in colour from sapwood. Extractives cause the colour change. Extractives are trace elements imparting various combinations of characteristics to heartwood, such as colour, fungal- and bacterial-resistance, reduced permeability of the wood tissue, additional density of heartwood, and abrasive deposits.
Tyloses are bubble-like structures that develop in the tubular vessels of many hardwoods during the changeover from sapwood to heartwood. Tyloses block the previously open vessels, preventing free movement of liquid. Red oaks form very few tyloses whereas white oaks produce many and this explains why white oaks are preferred for barrels. It’s possible to blow through a stick of red oak submerged in water and create bubbles. Whisky distillers are well aware of the “Angels’ Share,” which is the part of the spirit, usually about 2 percent, that evaporates through the wood of the oak barrel (Whisky Magazine, 2008).
Growth rings are the result of the cambium layer adding new tissue year upon year. The cambium layer (in temperate climates) becomes active in spring, reacting to chemical signals produced in the tree brought about by warming temperatures and longer daylight hours. During its active period the cambium layer adds open, fast-grown porous tissue to cope with the rush of water and minerals required of the freshly opened leaves. As the summer approaches and the initial high demand for food subsides, the cambium lays down denser, harder latewood, which adds strength to the trunk and branches.
At the centre of the tree cross section is the pith or medulla. The pith is the small core of soft spongy tissue forming the original trunk or branch.
3.2 Gymnosperms & Angiosperms – Differences 3.2.1 Gymnosperms Gymnosperms (conifers, softwoods) are simpler in structure than angiosperms. Gymnosperms evolved earlier than angiosperms and have some distinct structural characteristics. More than 90 percent of the wood’s volume is made of tracheids. Tracheids are long fibrous cellulosic8 cells approximately 100 times longer than their diameter. They range between about 2 mm and 6 mm (about 1/16″ to 1/4″) in length depending on the species.
The two main functions of tracheids are as structure for the tree and as conductors of sap – nourishment. Tracheids conduct liquid food up the tree after the living protoplasm has left. Water and minerals pass upward to the leaves from one tracheid to the next via osmosis. Osmosis is the process where liquid from a high water (weak) solution passes through a cell wall into a low water (strong) solution. In softwood trees water and minerals move upward from the roots initially through upward root pressure created by soil-borne water migration into the root tracheid cells. Secondly, there is also transpirational pull created by water evaporating from the leaves. This method of conducting foodstuffs is distinctly different to the method used in broad-leaved trees described later.
The cambium layer lays down different forms of tracheids at different times of year. In the spring, the tracheids laid down are thin walled with a large diameter and are lighter in colour. Late-growth tracheids are dark coloured, have thicker walls and a smaller diameter. The early-wood tracheids with their thin walls are better at conducting liquid than the later thick-walled tracheids. Both will conduct water, but a tree needs structure as well as the ability to transport liquid – there is a necessary balance struck between the two functions in tracheid cell structure.
A distinctive characteristic found in some gymnosperms is resin carried in resin canals. Pine, spruce, larch and Douglas fir have resin canals. These timbers have a characteristic scent when worked, and the resin can cause bleeding problems under paint and polishes. One way of setting the resin solid to reduce bleeding problems is to raise the temperature of the wood during kiln drying to 175º F for a sustained period. Genuine gum turpentine is a product of the resin from Southern yellow pine, a tree of the North American continent.
Medullary rays are narrow in conifers and invisible to the naked eye, so to see them it’s necessary to mount thin wood samples on a slide for examination under a microscope.
3.2.2 Angiosperms Hardwoods are more complex than gymnosperms. There are a number of specialised cells present in angiosperms absent from gymnosperms. For instance, the means of conducting liquid foodstuffs up and down the tree in nearly all cases is through the vascular tubular vessels. This is distinctly different to the liquid-conducting tracheids of conifers. The vessels in angiosperms form a bundle of pipes encircling the tree. The fibrous tracheids of hardwoods are much smaller than they are in conifers and because of their thick walls they are not well suited to conduct liquids. Unlike the softwoods, the rays of deciduous trees are often easily visible, e.g., in oaks, sycamore, maple, beech etc. Resin canals are rare in angiosperms, but some tropical plants such as the rubber tree produce gum and have gum ducts.
