Archive for the Category ◊ Wood ◊

Author:
• Friday, June 30th, 2017

sensing wood moisture content

Can you really sense, with any practical utility, the moisture content of wood simply by touching it? Yes. Let’s take a look.

An object feels hot or cool to the touch of your hand because of the flow of heat between your hand and the object. For example, an object feels relatively cool because it is drawing heat from your hand.

Remember how mom or dad could tell if you had even a bit of a fever just by touching your forehead?

Consider wood. The heat flow depends on several factors. The variable that we want to isolate is the moisture content (MC) of the wood. Wetter wood will draw heat from your hand faster and thus feel slightly cooler.

We want to keep these other factors constant:

  • The wood species – density is the key. Denser wood will transfer heat faster.
  • Surface texture. The greater contact of a smooth surface will transfer heat faster than a roughsawn surface. To a lesser extent, a diffuse porous wood such as cherry transfers heat faster than a ring porous wood such as oak.
  • The temperature of the wood, especially relative to your skin temperature, of course, affects heat flow. Heat energy flows from the warmer object, usually your hand, to the cooler object, usually the wood.
  • The surrounding temperature and moisture conditions will likely affect your perception of hot and cool.

Those four other factors are constant in the typical situation of sorting through boards at the lumber dealer – a particular species, roughsawn, at the temperature and surrounding conditions on that day.

So, can you sense differences in MC based on how cool or warm the wood feels to the touch of your hand? I think I can. No, I cannot tell the difference between 8% and 10%, but with the aid of a pinless moisture meter, I have shown myself that I can tell the difference between, say, 8% and 14%, and even closer than that. Every time? No, but reliably enough that I can use my sense of touch to quickly sort through boards of one species at the lumber dealer and help me make choices. Larger differences are more apparent. This also can alert me to certain situations, such as a poorly stored 10/4 board that is much wetter on one side than the other.

The differences I am sensing are relative, not absolute, but that is what I am concerned with as I sort through the piles. It is even possible to “calibrate” my hand for absolute measurements for a particular pile of wood by taking a couple of readings with a pinless moisture meter, and correlating that with what I feel, but I wouldn’t rely on that and it is not what I need.

I am not suggesting you discard your moisture meter. I also understand that the “measurement” is shallow. And I’m not going to put my lips on the wood; that’s weird. Yet, with some awareness and very little practice, you can get a pretty good sense of the relative moisture content of boards just with your hands.

What’s your sense of this?

Category: Wood  | 4 Comments
Author:
• Tuesday, December 20th, 2016

inlay banding

Here is another product that I think you will appreciate knowing about, which I alluded to in the previous post. It is inlay banding made in North Carolina by Matt Furjanic, sold on his website Inlay Banding.

This is beautiful material made with precision from highly select, solid hardwoods. Only some of the narrow outer stripes are made from veneers. Most of the bandings are about 1 mm (3/64″) thick – enough to work with as real wood instead of as curled up, long potato chips like some other bandings. Lengths are generally 36″.

These bandings consist of all face-grain wood, not end grain, so they look great and finish beautifully and predictably. This also makes them easy to work with. They glue well into the slot and pleasantly scrape flush to the surrounding wood. By the way, scraping works much better than sanding for flushing, especially for banding containing ebony, which tends to muddy the lighter woods if sanded.

They come in a wide selection of patterns, mostly low-key. These will enhance your projects and not be obtrusively glitzy.

I knocked together a long plywood box to safely store the bandings in my shop:

storage box for inlay banding

Matt also sells guitar bandings, stringing and stock for line-and-berry work, federal shaded fans, and very select thin stock for making your own inlay materials. He also does custom work, and sells some great looking boxes, which, of course, feature inlay bandings.

This is the best inlay banding material I have found. This review is unsolicited and uncompensated. The last paragraph of another post explains why I present these reviews.

One more thing. Some woodworkers may balk at including woodwork made by someone else in their pieces. This makes no sense to me. Virtually all of our work contains elements made by someone else, such as hinges, handles, locks, other hardware, and glass. And don’t forget the finishing materials. It is how you use these materials that counts. Even aside from this, we have had lots of help, starting with the guys who cut down the tree, drove the trucks, milled the log, and so forth. I am happy to add expertly-made inlay such as this to my work.

Author:
• Sunday, November 13th, 2016

crosscutting lumber

So often I bring to mind the admonition from James Krenov in the Fine Art of Cabinetmaking, “Cross-cutting should always be preceded by careful thought.”

When divvying up rough stock for a project, it is those early crosscuts, often particularly the very first one, that so much determine the successful use of the wood, and in turn, the entire success of the project.

We tend to let our guard down at this early stage because the lumber is rough and the cuts are rough, so it seems like little could go wrong. We are not naturally in a precision frame of mind as when approaching joinery work. Moreover, it seems like there is so much wood now, maybe much more than needed.

But beware, these early breakdown crosscuts will in large part dictate the figure and color matching of the wood in the finished piece. After The Crosscut – the one that felled the tree – and the sawing and drying of the boards, these initial crosscuts in your shop are critical to the efficient use of your expensive wood.

As with most matters in woodworking, winging it is not often rewarding. So think it through with the measured drawings nearby, and tape measure and chalk in hand. Be alert. Look at the wood, study the figure and grain, find the defects. Make thoughtful decisions.

The eternal woodworking quest for a board stretcher remains unfulfilled, so I heed the advice of the master.

Category: Wood  | 2 Comments
Author:
• Monday, October 31st, 2016

live edge wood

The rustic look of furniture featuring a live edge board currently has wide appeal, as it seems to draw a response even from those people who otherwise pay little attention to the intrinsic beauty of wood.

Here are two uncommon options for designing with live edge wood: let the natural “path” of the board’s live edge guide the whole structure of the piece or, similarly, determine the shape of just other components of the piece. The live edge can be followed loosely or closely.

In the small table above, the front rail in ash follows the general sweep of the live edge of the walnut top. As with other pieces, I carefully striped the bark and prepared the live edge to retain almost all of the organically interesting wavelets. Thus, the live edge follows the peaceful flow of the ash rail but also presents an exciting contrast in form.

The rail construction is a bent lamination. I worked out the angles and joinery in a full size drawing because they were trickier than I first imagined.

In the wall shelf below, I again preserved the undulations as well as the fine ripples in the curly big-leaf maple board. The pear drawer front is a rare specimen with exquisite flame-like heartwood. As seen in the second photo below, I matched its contour to the waves in the maple’s live edge.

live edge wall shelf

live edge design

The photos of this piece are a bit weak but the actual piece projects a distinctly “live” feel. I really let the wood “design” the piece.

These are just some ideas for working with live edge wood. Though they involve a lot more trouble in construction, the wood is inspiring and sustaining.

wall shelf with drawer

Category: Wood  | 5 Comments
Author:
• Friday, June 20th, 2014

ash curves

From baseball bats to crates to tool handles, ash certainly earns its keep as a versatile workhorse wood, but how about for fine furniture?

For this discussion, ash, as a furniture wood, refers to what is generally sold as “white ash” or just plain “ash,” most of which is Fraxinus americana, though there are several other commercially significant ash species.

Ash has a prominent and usually fairly uniform annual ring figure produced by the great difference between the large earlywood cells and dense latewood. It lacks the flashy visible rays of the oaks, and the large majority of it is composed of unimposing light blonde sapwood. So, is ash a boring wood?

Used unimaginatively in low-end furniture, yes, it is rather boring. However, like most products of nature’s bounty, the key is how it is used and what the craftsperson can draw from it.

To my mind, one of the prime virtues of ash is that its rift-cut or quartered surface is great for bringing forth and enhancing artful gradual curves. The uniform figure of the wood seems to sensitize the eye to subtle design. It energizes the form of a piece. Sometimes it reminds me of the raked sand in a Japanese Zen garden – not boring, but peaceful.

Ash can be a pleasing contrast to more intrinsically glamorous woods, but it can also shine on its own. Curly ash is beautiful and impressive, yet retains the species’ inherent composure. I recently picked up some beautiful curly pieces – I’m thinking thick veneer drawer fronts for these – from Kevin Koski at Curlymaplewood.com, where you can find lots of other gorgeous curly species. Also, ash heartwood has a nice soft brown color that creates interesting contrast when used judiciously alongside the sapwood.

curly ash

With green-to-oven-dry shrinkage values of 4.9% radial and 7.8% tangential (T/R = 1.6), ash is decently stable, and it generally works well with machines and hand tools. I’ve enjoyed using it for frame and panel work, legs, drawer parts, and in bent laminations. The species presents a challenge and an opportunity for thoughtful design and balance in a piece.

I like ash finished with a less-is-more approach, using a “water white” acrylic water-base or maybe thin bleached shellac.

In recent years, ash trees in the central and eastern US have become seriously threatened by the emerald ash borer. Here are some ways to help avoid spreading the infestation.

By the way, all of the “Woods I love” posts, with more to come, can now be conveniently viewed on a single page as one of the Series Topics.

bent lam cutoff and tool handle

Category: Wood | Tags:  | Comments off
Author:
• Thursday, January 30th, 2014

IMG_1170_edited-2

The visual beauty of wood, its warmth to the touch, and lovely sound properties are so enticing that we might neglect the variety of pleasing scents many species have to offer. Smells are registered deep in the primitive brain in the limbic system where they are associated with memories and emotions, so this is a powerful aspect of wood.

When recently working with some nice quartersawn Douglas fir, the aroma brought me back to my youthful days of projects in humble fir plywood and the simple joy of making things. Continuing to nowadays, the particular scent of a species released by its sawdust and shavings is part of the experience of woodworking and thus, in my mind, part of the personality of the piece.

I think of, as examples, the shop being filled with the aromas of walnut or spicy Port Orford cedar or even the unmistakable horse barn smell of zebrawood. Using canarywood recently for the first time was a pleasant olfactory surprise.

Unfortunately, the aromas then usually disappear under layers of finish, unavailable to the end user of the piece. Of course, with most work, especially things like tables, there’s no getting around that. However, in some casework there is an opportunity to add a wonderful aspect to the piece that will be enjoyed for years to come.

Consider using aromatic woods, left unfinished, for interior drawer parts, case back panels or partitions, and box linings. The “cedars,” sassafras, and even pine are some options.

By the way, I avoid using oil or oil-varnish finishes on the interior of cabinetwork. A light application of a hard-drying varnish or thin shellac are better choices.

Pictured above are, from top to bottom, quartered Doug fir, canarywood, Claro walnut (left), Port Orford cedar (right), and zebrawood. But you have to meet the woods in person for the full experience.

Category: Wood  | 2 Comments
Author:
• Tuesday, July 02nd, 2013

IMG_0400_edited-2

Take a look at the end grain of this live-edge board. Without causing undue stress and tension, do you notice anything?

OK, enough goofy hints.

You probably notice that the board is from a tree with an off-center pith. The wider growth rings on the far right side, compared with the corresponding years on the left side, represent tension wood.

When a tree trunk leans due to environmental stresses such as gravity, snow, or light availability, it wants to redirect its growth upward and thus bows. To accomplish this, it forms aberrant wood known as reaction wood on one side of the tree, often recognized by its wider growth rings with the pith located off center.

In softwoods, the reaction wood, called compression wood, is usually on the underside of the bow, while in hardwoods it known as tension wood and is usually found on the upper side of the bow. The growth ring width asymmetry and consequent decentration of the pith can be dramatic in softwoods, but mild to absent in hardwoods. Reaction wood differs from normal wood in cellulose content and structure.

There are visual and behavioral clues to the presence of reaction wood.

It may be difficult to recognize in roughsawn boards at the lumberyard. Look for growth ring asymmetry in flatsawn boards. This is easy to notice in a live edge board but possibly not in a board with sawn edges. An unexplained lengthwise split or a pronounced crook (a curve in the width plane of the board)  may be caused by the abnormally high longitudinal shrinkage of reaction wood.

After the wood is in your shop, take note of behavioral clues such as persistent and unexplained distortion after milling. Another possible clue that most woodworkers have encountered is a stubbornly persistent fuzzy surface on an area of wood despite repeated attempts at smoothing it – you sand it and the fuzz never goes away. More confusing may be an unexpected excessively blotchy look that shows up after finish is applied.

This wood does not want to play nice; avoid it. I have read, however, of wooden bow makers taking advantage of the abnormally greater strength of tension wood.

There are exceptions, of course. This is wood – every tree, every board is an exception!

IMG_0402_edited-2

Being very cautious, I’ve monitored this walnut board with suspicion for a long time now, through partial milling and changes in moisture content. There are only some old shallow surface checks and a little distortion that has settled. I think it is safe to use in a project.

It pays to watch the wood.

Category: Wood  | 4 Comments
Author:
• Saturday, June 22nd, 2013

IMG_1089_edited-2

4. Interpret the information and use it.

“Yes, I am asking you to fuss with wood.”

-James Krenov, from The Fine Art of Cabinetmaking

In this final installment on the topic of moisture meters, I will broaden the discussion to the management of wood that has been dried and brought into the shop, from wherever you have obtained it, because it still needs attention before it is ready to be used in a project. A moisture meter can help here.

When a new board comes into the shop, I write the date and moisture content (MC) on it. I refer to the back of the Lee Valley Wood Movement Reference Guide to know the equilibrium MC for the ambient relative humidity (RH) indicated on my shop hygrometer. (Temperature is a negligible factor for practical purposes.) The FPL Wood Handbook has the same information. I try to keep the RH within about 40 – 65%, winter to summer, with the use of a humidifier and dehumidifier, as needed.

Unless I am lucky, the wood has some adjusting to do. Therefore, I store it so air can circulate on all sides of each board by storing it horizontally on a rack and stickering it, or leaning it vertically against something. Sometimes I will do an initial light skim planing to get a peek past the rough surface, and to facilitate measurements with the pinless meter.

Then I keep an eye on the wood, checking the MC in a few days to see if it is moving. Depending on the initial MC, species, and thickness, I look for the MC to level off over the next few weeks. The wood is then ready for the first dressing.

Another approach is to look for when the MC of the new wood matches that of wood of the same species that has been in the shop for a long time. Beware, however, of the density issue with pinless meters that was discussed in the previous post. Also beware of the possibility of a moisture gradient through the thickness of the wood, especially in thick stock.

I usually use the pinless meter for this because it is faster and doesn’t make holes in the wood. However, if surface or density issues seem to be confusing, or if the stock is thick and I want to look for a moisture gradient, I will turn to the pin meter for additional information. If I could own only one? Pinless, probably. No holes.

Could this be done without a moisture meter? Sure. Patience and experience will work. Even quick monitoring with a straight edge on flatsawn boards will be informative. I like the convenience and greater reliability offered by the meters to help avert disappointments.

Unless it is very tame straight-grained wood and the final thickness is only slightly reduced from the initial state, I usually dress rough stock in two stages, even after it has reached uniform equilibrium MC. For example, to get a finished 5/8″ from a rough 4/4, I will first joint and thickness down to 3/4″, taking approximately equal thicknesses off each side of the board.

I watch the wood. Did the initial jointing stay flat and true? Did new a twist arise, or maybe a slight bow? These surprises can come about from internal tension releasing when some thickness is removed. Odd grain and case hardening are among the possible causes. These issues will usually manifest their effects quickly, sometimes immediately.

Then I take the wood down to final thickness, removing any slight distortions. If the distortions are large, or reappear, I usually find another board.

Resawing is another matter, discussed here, but requires knowledgeable observation and understanding casehardening to avoid disappointments.

Understand the wood. Watch the wood. A moisture meter can help.

Category: Wood | Tags:  | Comments off
Author:
• Sunday, June 09th, 2013

IMG_1087_edited-2

3. Important factors that affect the readings

This is the third of four keys to making effective use of a moisture meter. Even properly taken readings are subject to factors inherent in the design of the meter.

Pin meters are affected by temperature. They will overestimate the moisture content (MC) in a hot environment (wood temperature), and underestimate it in the cold. This will probably only be significant in a cold lumberyard where the meter will read perhaps 1-3 points less than the actual MC. Consult the table that comes with the meter.

The species of wood also affects pin meters but, in the MC ranges we are typically measuring in the wood shop, there is little difference among most species, in the range of one or two points.

Measuring boards of one species in a consistent environment will cancel any significance of these two factors.

Surprisingly, wood density is an unimportant factor. Measuring with the grain, versus across it, is a slight, but generally insignificant factor. Of course, wet spots on the wood (such as melted snow) will greatly distort the readings.

In summary, for pin meters, there are not too many factors to be greatly concerned about. The main issue is to be aware of the depth into the thickness of the board at which the meter is measuring, and be aware of the possibility of a moisture gradient, especially in thick stock.

Remember too, the meter measures the wettest layer between the probes. This is usually the deepest point of penetration by the probes if the wood is still in the initial drying process, though not if it is rapidly gaining moisture.

And, of course, they make holes in your wood!

——————————-

Pinless meters are significantly affected by wood species, density, and, as addressed in the previous post, surface quality.

The “species” is really just a proxy for density, and this can be confusing. The tables or programmable functions that accompany the meter are necessarily based on average density values for a given species. However, because each tree is unique, the densities of different samples of a species can vary greatly.

The manufacturer supplies a formula to calculate your own correction factor, but it requires an accurate measurement of the specific gravity (density) of the sample of wood in question, which is usually rather impractical, especially when you do not already know how much of the measured weight is water.

Furthermore, when assessing newly acquired wood, referencing boards of same species on the racks in your shop, fully equilibrated, is not necessarily helpful since they may be quite different in density.

I recently bought some white ash which measured 13-15% MC with the Wagner pinless meter using the correction table. This seemed oddly high for wood that was kiln dried and stored indoors. I brought the wood to my shop, stickered it, and after a couple of weeks, the apparent MC decreased very little. After over two months, it was reading only 12%. Other ash that had been in my shop for a long time was reading about 9%, about what I would expect in the ambient humidity.

So, what’s going on? As I suspected, the recently acquired ash is just denser than the average value for ash used for the Wagner tables. How do I know? Well, two months ought to be plenty of time for the wood to equilibrate and it did not change much over that time. Furthermore, the pin meter, which is unaffected by wood density, verified that this wood was now about the same MC as the other wood in my shop, and there was no gradient through the thickness of a fresh crosscut.

Thus, we have two easy ways of dealing with the density issue affecting pinless meters: time and a pin meter.

Next: We’ll distill all of these technicalities into practical options for wood management.

Category: Wood | Tags:  | 4 Comments
Author:
• Thursday, May 30th, 2013

IMG_1085_edited-2

2. Taking the readings

Whether a moisture meter or your blood pressure, if you don’t take the readings properly, they won’t mean much. So let’s take a look.

Pin meters:

The pins must be inserted and held in without backing off, which will create a small air gap, or cause the spring-loaded activation button to release. This can take considerable force, especially if using longer pins. Though longer pins are available, even big hammer-in probes for some meters, I almost always use the default pins on my miniLigno that penetrate about 1/8″.

The pins at the left in the photo penetrate about 1/4″, and even those are difficult to push into dense woods, and I find they tend to break.

IMG_1083_edited-2

One of the advantages of a pin meter is its ability to check precisely for a moisture gradient through the thickness of a board that has not reached uniform equilibrium moisture content. In the photo at the top, my pinless meter, which has a measuring depth of 1/2″, could evaluate just about the full thickness of the 1 1/8″ Claro walnut board. Remember however, those would be readings of the average moisture content in the measured volume of wood. By crosscutting the wood, then promptly comparing pin readings taken in the end grain near the surface and near the center of the board, a moisture gradient can be detected. The same can be done, sometimes with dramatic results, in a stick like the 16/4 Doug fir in the photo.

I have found little or no difference in pin readings taken along versus across the grain. Furthermore, there is usually little or no difference in the readings for most species whether the meter is set on “wood group” 2 or 3 on the miniLigno meter.

Pinless meters:

Readings are best taken on a smooth, flat wood surface with the length of the sensor aligned along the grain. In the photos of the cherry board, below, my Wagner L609 meter is reading 9% with the sensor along the grain of smooth wood, but 7% on the immediately adjacent rough surface. It read 11% with the sensor placed across the grain of the smooth, flat wood. These relationships are typical. Note also that if the wood surface is not flat in any case, the readings are likely to be relatively underestimated.

IMG_1081_edited-2

IMG_1082_edited-2

At the lumberyard, you probably won’t have the luxury of reading off a smooth surface, but at least you can make comparisons between similarly rough boards.

Pinless meter readings must be corrected for the density of the species. Some meters allow this to be programmed in before taking a set of readings, but with my meter I must hassle with having to add or subtract an amount based on tables in a little booklet that comes with the meter.

By the way, do not measure thin wood in the manner as shown below, unless you want to average it with the moisture content of your workbench!

IMG_1084_edited-2

Next: In part 3 of the series, we’ll look at important factors that affect the readings, especially for pinless meters.

Category: Wood | Tags:  | Comments off