Drying Wood

drying-woodThis is an excerpt from “With the Grain: A Craftsman’s Guide to Understanding Wood” by Christian Becksvoort.

A commonly encountered misconception is that wood breathes. As we know, heartwood is composed entirely of dead cells, while sapwood has some living cells, which die after the wood is cut. Nonetheless, wood is an organic substance that by its nature responds to climatic changes. Moisture is absorbed or given off as the seasons dictate.

When the relative humidity rises, the wood fibers absorb moisture that penetrates from the outside and causes the wood to swell. As the humidity decreases, excess moisture is given off by the fibers to be reabsorbed by the surrounding air. Wood is constantly trying to maintain a balance between its moisture content and that of the surrounding environment. This balance is called the equilibrium moisture content (EMC). Simply expressed, it is the amount of moisture present in wood at a given temperature and relative humidity over a period of time (Fig. 4-9).

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Fig. 4-9

A closer look at Figure 4-9 shows that humidity is only one factor in determining EMC. Temperature also plays a role. For instance, at a given temperature as humidity rises, the EMC of the wood increases dramatically. This is to be expected. On the other hand, as relative humidity remains constant and temperature rises, the EMC of the wood goes down. Water in the cell walls is in liquid form. As the temperature goes up, the water becomes gaseous and escapes into the warmer air.

Relative Humidity

Relative humidity is expressed as a percentage of the amount of moisture that the air is capable of holding at a given temperature. Warm air can hold more water vapor than cold air. For instance, at 86°F (30°C) and 100 percent relative humidity can hold five times as much water vapor as air at 43°F (6°C) and 100 percent relative humidity. Hence, it is a good idea for a well-equipped wood shop to have a thermometer and hygrometer.

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Fig. 4-10. (A) Average relative humidity in July, at noon, local time. (B) Average annual precipitation, in inches. (C) Average recommended moisture content of wood for interior work.

Location, as well as time of year, determines the average humidity. Figure 4-10 shows the average humidity in the United states for July, as well as the average rainfall. The third map takes both of these into account, as well as the corresponding equilibrium moisture content from Figure 4-9, to arrive at a general composite map of average moisture content of wood intended for interior use in various parts of the country. This map should only serve as a rough guide, because local conditions can vary.

Air Drying

Numerous considerations influence the air drying of lumber, among them:

Climatic conditions. Generally speaking, very little drying of lumber is possible during the winter, particularly in those areas where the temperature remains below freezing. Moisture close to the surface can evaporate by the process of sublimation, whereby the water goes from a solid state (ice) directly to a gaseous state (vapor) without becoming a liquid. In areas where winter temperatures are relatively mild, some drying will occur, as long as rainfall and humidity are not excessive. Drying rates are variable and often very localized. The location of the drying pile and even its orientation to the sun and prevailing wind all influence the rate of evaporation.

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Fig. 4-11

Species. The wood species makes quite a difference when it comes to length of drying time. Specific gravity is a fairly good general indicator of drying rate. The lower the specific gravity, the faster the drying time. The softwoods and lighter species of hardwoods dry faster under favorable conditions. The percentage of sapwood and heartwood also plays a part. For example, sugar maple dries faster than Northern red oak with roughly the same specific gravity, but sugar maple has more sapwood. Figure 4-11 lists the approximate air- drying times of some native woods.

Thickness. The old rule of thumb “one year of drying for each inch of thickness” has no basis in fact. First, it does not take species into account. Second, drying time is a function of the square of the thickness. This means that 8/4, or 2″ (5 cm) stock takes four times as long as 4/4, or 1″ (2.5 cm) stock. In fact, for some species the drying time is even longer than the square of the thickness. This is one reason (along with the differential between radial and tangential shrinkage, described in Chapter 5) why it is next to impossible to dry entire logs without serious cracking or checking.

Grain orientation. Quartersawn wood is slower to dry than plain-sawn wood. The ray cells aid in drying, and although they appear more prominent on quartersawn wood, not nearly as many are exposed on the face of the board.

Pile construction and foundation. The actual method of stacking the wood has a lot to do with the drying rate. Adequate space left around each board aids in drying. Many smaller piles dry faster than one large pile. The pile foundation should be well off the ground to allow for free air movement underneath. Weeds and debris should not obstruct the air flow. Finally, the ground should be well drained, with no standing water.

Meghan Bates

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Meet Kara, the Newest Addition to Lost Art Press

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Photo by Matthew Albritton

Editor’s note: Last month we asked Kara Gebhart Uhl to help us with editorial tasks at Lost Art Press. During the last decade, John and I have taken on book projects that are more and more ambitious. And in the next 12 months we’ll be announcing several additional ambitious projects that will take lots of brainpower and red ink.

After months of agonizing over how to manage these projects and keep our sanity, I read a blog entry that struck me like an electric shock. One of my former editorial employees, Kara, was lamenting/celebrating the fact that her kids were all going to be in school during the day.

I sent her an immediate email. She knows woodworking. She knows our editing style. She can already read my mind. And no one – no one – is as organized and on time as Kara.

She agreed to help us out about 10 hours a week and has already started chewing up our backlog of editing – the next Charles Hayward volume is now two months ahead of schedule.

As you’ll see below, Kara is crazy overqualified to work with us, but we hope to treat her well and hang onto her for many years to come.

Fifteen years ago Chris Schwarz hired me as an assistant editor at Popular Woodworking Magazine. I had a magazine journalism degree, and I was hired for my writing and editing skills. My only woodworking skills at the time involved a turned lamp I made in junior high shop class.

Chris served as a mentor, helping me improve my writing and editing, while also teaching me the art of woodworking. I took classes, including a week-long class with Lonnie Bird to build a Shaker end table, and a chairmaking class with Don Weber. Several other pieces see daily use in my home, including a knockdown Arts & Crafts bookcase.

But I never truly fell in love with the physical aspects of woodworking. I did, however, fall in love with the idea of woodworking and, more importantly, the folks who did it. My absolute favorite pieces to write for Popular Woodworking Magazine was a series of articles called Great Woodshops. I’d spend a day in John Wilson’s The Home Shop or in Brian Boggs’s “laboratory,” and I’d simply look and listen, and then retell.

I served as associate and managing editor at Popular Woodworking Magazine, and helped launch Woodworking Magazine. But eventually my love of the craft of writing led me to Writer’s Digest magazine, which was two floors up in the same building.

My daughter, Sophie, was born in 2008. My twin boys were born in 2010. During this time, I quit my job at Writer’s Digest magazine, and went about the daily tasks of raising three young children. We moved into a foursquare built in 1901 in Fort Thomas, Ky., right across the river from Cincinnati.

I worked as a freelance writer and editor, doing the occasional final binder reads for both Popular Woodworking Magazine and Writer’s Digest. I maintained a column at Writer’s Digest, wrote ads, edited Writer’s Market books, and wrote profiles about interesting people for our small city’s blog, http://www.fortthomasmatters.com.

I also wrote about parenting on my personal blog, http://www.pleiadesbee.com, and my essays were picked up by TIME: Healthland, The New York Times Motherlode (now called Well Family) and The Huffington Post. It was in the comment sections of those blogs that I developed a thick skin.

I still maintain my freelance workload, all the while working toward my dream of publishing a picture book. I’m represented by Jordy Albert of The Booker Albert Agency and I currently have two out on submission. As Sylvia Plath once said, “I love my rejection slips. They show me I try.”

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After eight years of being home with my children, working during naps, nights and weekends, my days have changed. In August all three of my children went back to school, full day. What once were a few precious hours here and there has turned into six solid hours at home. Chris, aware of this life change, emailed me, asking if I was interested in helping out.

And so, in many ways, I feel like I’ve come back full circle. I’m once again working with my former mentor, and serving a community of craftspeople who I’ve grown to admire greatly over the years, people who believe in the beauty of working with one’s hands, building objects designed to last longer than themselves. I’m happy to be here.

— Kara Gebhart Uhl

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Lost Art Press Forum: The Experiment has Ended

LAP_FINAL-ARTWORK_V1When we launched the Lost Art Press forum last fall we decided to make it a one-year experiment. This week, John and I are touring a printing plant that we use for Lost Art Press and we had a frank discussion about the forum during the four-hour drive.

The bottom line: We’re shutting it down.

While we’ve been generally happy with the forum in terms of its civility, it has also been a time suck for me, John and Meghan Bates. And when we ran the equation through the goose, we decided that monitoring the forum was a lot of effort that we’d rather spend on publishing books and writing blog entries.

So if you have a question about a book that stumps you, you can always send a message to help@lostartpress.com. Or you can leave a note on the blog. We will still do everything to help you, just like we have since we started this company since 2007.

Thanks to everyone who has participated in the forum in a civil manner – it was greatly appreciated by all of us.

— Christopher Schwarz

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Sine Curve Tutorial

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To develop the curves in the various brackets – here the support for the back fence on the lid of a desk – I followed the ancient practice of melding arcs of a circle along a straight line.

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I begin by making a few concept sketches to get an intuitive feel for the curve I would like to see transition the horizontal lid surface to the vertical back fence. I’m going to go with the shape in the first drawing.

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From the sketch, it reveals that the overall form suits that of a 1:2 rectangle. (An octave, by the way – but that’s another story). Next, I divide the horizontal length into four equal segments. The first of these segments defines the flat at the top of the curve. I then draw a baseline for the sine curve from this segment point to the lower right hand corner, then divide that baseline into three equal segments.

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To find the focal point of the arcs – which will each be one-sixth of a circle’s circumference – I set the dividers to the length of the segment (which is the chord of the arc) and swing out intersections to locate the focal point of the arc. Next, without changing the span of the dividers (because the chord equals the radius for sixth sector arcs as you may remember from Mr. Hammersmacker’s seventh grade geometry class), I swing the arc from the focal point to each segment point. The transition between the two arcs is seamless – proven to be so because a line connecting the two focal points will pass through the arc’s transition point.

Sweet 16

— Jim Tolpin, byhandandeye.com (drawing by Andrea Love)

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Where Chair Comfort Comes From

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Many woodworkers avoid chairmaking for the joinery, the angles, the special tools required or the materials (green, rived stock?). And when it comes to designing a chair, even experienced woodworkers are hesitant to give it a shot because they are afraid they will produce a buttocks-torture device instead of a comfortable chair.

Producing a comfortable chair is the combination of many factors, but all of them are easily controllable. In my short 13 years as an amateur chairmaker and designer, here are some of the design details that I think are overlooked.

The Saddle
Many first-time chairmakers carve the seat so deep you could bake a Bundt cake in it. I’ve seen saddles that are 1” deep and so dramatically shaped that they would look at home on a Klingon battle cruiser.

A little saddling (3/8” or so) is nice and it makes the seat appear to flow. But you can get away with little or no saddling and make a perfectly comfortable chair.

The trick – in my experience – is to design the chair so the front edge of the seat doesn’t bite into the sitter’s thighs. You can do this several ways.

No. 1: Shorten the legs a bit so the sitter’s feet rest flat on the floor and their thighs are just slightly above the front edge of the seat. Many shorter people hate factory chairs because the front edge of the seat restricts the blood flow after a few minutes.

Just like with a table, it’s easy to make it too high. But making it a little lower than typical has zero downsides.

No. 2: Take a jack plane and round off the front edge of the seat. You can also do this with a spokeshave – hollowing out two areas for the thighs. This five-minute operation creates the illusion of a saddle and increases the comfort.

The Back Legs
The least comfortable chairs I’ve sat in had a seat that was parallel to the floor. It makes the sitter feel like she is being pitched forward.

I like to have the seat drop 1” (at least) from the front edge of the seat to the back edge. I achieve this by cutting the back legs shorter. Cutting the back legs also has the benefit of angling the back of the chair backward, increasing the comfort.

Don’t over-do it. After removing 1-1/2”, it will start to feel weird. A good way to experiment with this is to prop up the front legs on a 1”-thick scrap and sit in the chair.

The Angle & Height of the Back
The backrest doesn’t have to be bored at a reclining angle. You can bore the backrest at 90° and use the fact that the back legs are shorter to make the chair comfortable. However, I do like to recline the back a few degrees back (once you get into chairmaking you’ll find that all the angles are as easy as 90°).

What I have found to be quite critical is the height of the crest rail or backrest. In general, lower seems to be better. Once you put something above the shoulder blades, the lumbar seems to suffer.

You can design a chair that has a high backrest, but I think it’s best to also have something below as well for the lumbar (think Jennie Alexander’s chair).

About the Chair Above
Roy Underhill made the chair in the photo at the top of this entry. It’s a reproduction of a chair we both saw at Stratford-upon-Avon last summer. To the eye, it looks uncomfortable. The seat is flat. The arms and seat height are lower than a typical modern chair. And the area created by the arms seems like a tight fit (it is for large people).

But the chair is remarkably comfortable. And, if you watch the current season of “The Woodwright’s Shop,” you’ll see how it’s dirt simple to build.

— Christopher Schwarz

Posted in The Anarchist's Design Book, Uncategorized | 4 Comments

The Number of the Name is….

sector for fractions While I mostly use the sector for doing design and layout work in my shop, I realized recently that it’s also a great tool for showing someone (especially your kids) an intuitive approach to understanding fractions. Here’s how I’d describe what’s going on in the drawing above:

Because I want to find out where a point four-sevenths of the width of a board would come to, I set the legs of the sector to touch each edge of the board to denominate (i.e. to name) the kind of divisions I’m looking for. Here, that would be seven – the denominator. Now I want to enumerate (i.e. give a number) to how many of those sevens I’m looking for – in this case the numerator is four. The job of the dividers is to grab this numerator above the denominator value on the legs of the sector in order to transfer the setting to the face of the board. For me (and my kid), this drawing offers a decent visualization of why the numerator goes over the denominator. You can learn more about the sector in excruciating detail in “By Hand and Eye;” and in a somewhat less excruciating matter in “By Hound and Eye.”

— Jim Tolpin, by handandeye.com

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Forum Update 9/26

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Good morning! Another weekend over and another busy week is upon us. No matter how crazy life is, make sure to take some time to read the forum and see what your fellow woodworkers are up to. Remember, if you have a question about our products, procedures in our books or anything related to Lost Art Press, the fastest way to get an answer is our forum. Check it out here.

No. 7 Adjustment Issues
Kendall took apart his Lie-Nielsen No. 7. to sharpen the blade but now that he is putting it back together he cannot get the blade to adjust below the sole. He is looking for any help on what he may be doing wrong. Let’s see if we can prevent him from having to make a call into Lie-Nielsen. Help him here.

Handworks 2017
Does anyone who has attended Handworks have a recommendation for a place to stay? Steve is ready to get his plans together and is looking for input.

Spare Bedroom Workshop
Mark and his girlfriend have found a house that they love and want to buy but there is no garage or basement to use as a workshop. Mark is looking for feedback from anyone who has used a spare bedroom as a shop before. Did it work out? How was the noise? Was dust all over the house?

Crucible Dividers
Jason likes the pictures of the Crucible dividers but wants to get to the point and find out how they work. If you have a pair, let him know what you think.

Hot Hide Glue Gelling Quickly
Josh has had success with hot hide glue on small pieces but has had no success with it when trying to glue up a panel. Every time he finds he is unable to close the joint. He is wondering if anyone would be able to help with why this is occurring.

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Staked Chair
Travis has made a pair of staked chairs from “The Anarchist’s Design Book” and they turned out great. (Photo at top and to right.) The beveled edges are a great touch!

Meghan Bates

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