Considering Wood Movement
Running a sawmill and drying my own lumber has taught me a lot about wood movement. I know that some lumber, like cedar, dries quite flat and straight, and other lumber, like sweetgum, will dry like a potato chip. Quartersawn white oak lumber almost always dries with the ends pulling away from the center of the log, making a board with a nice sweeping bow. I also know that boards that are sapwood on one side and heartwood on the other will dry with a distinct cup. These are things that happen when wood dries from green to air-dry or about 20% moisture content, which is where the dramatic movement occurs.
Even after air drying and kiln drying wood still moves with humidity changes, and as woodworkers we have to consider this seasonal movement. This is the kind of thing I think about a lot, and recently I gave myself the chance to really think about it. I was building a table and the wood I wanted to use was not dry. It was white oak which sat on sticks air drying for a little while, but was still wet enough to be considered “green”. I decided that I new enough about wood movement to make it work, and since the table was a little rustic, that I should go for it.
The bases for the table were simple. I made sure all of the grain was going the same direction, so the shrinkage would happen evenly. It also worked out nicely that all of the pieces would have air movement on all sides so they would dry out at the same rate. So far all was good. I proceeded with the top. It was a glued-up top with breadboard ends (one board on each end perpendicular to the field). No big deal. If you do your breadboard ends correctly, everything can slide and allow the wood to move. I took all of that into consideration.
There was one thing I did not take into consideration. You see my brother tends to use my shop at night. I usually leave stuff in his way–after all, it is my shop. He has to move what I am working on to do his work, and he often does. He paid no attention to the fact that my wood was not dry and had no previous reason to, since I don’t usually use wood that is so wet. The parts that I carefully stacked with sticks so that they would have air movement on all sides were now just laying down flat on a table. In one night all of the parts developed an amazing cup because the sides exposed to the air were drying and the sides on the table were not. This all happened in one night. And since my brother usually works late, it was a short night at that. I was able to get the lumber back to flat by soaking the side that was up and drying the side that was down. All ended fine, but this created a lot of extra work and a lot of extra consternation on my part. And, I thought I worried about wood movement before.
This is an extreme example of wood movement, but the lessons learned apply even to dry wood. Make sure that pieces that need to stay flat have air movement on all sides, especially before the project is assembled. And try to hustle. If you take the time to make flat pieces, get them assembled before they can move. Remember, things can literally go bad overnight.
For fun here is the table the was moving on me. I had to go back twice to trim the breadboard ends flush as the boards shrunk, even after I left them 1/4″ short on each end to allow for some of the shrinkage.
The top on this table shrunk more than 1″ in width as it dried.
Kiln-Dried Walnut Is Not Steamed Walnut
I mill, dry, and use walnut on a regular basis, especially now that walnut is back in style. It wasn’t that long ago that everyone was tearing out dark cabinets and putting in the maple to lighten things up. Now, walnut is used regularly and often stained to an “espresso” color, which means really dark. Some folks would swear off staining walnut because it is naturally so nice, but I am not one of them. I, personally, almost always stain walnut, even if I just want it to look like walnut (more about this in a later posting). This got me thinking about the color of walnut, and no discussion about walnut color can start without talking about steaming.
This walnut sample was not steamed before drying. Notice the distinct line between sapwood and heartwood.
Steaming has one purpose and one purpose only – to change the color of walnut. Here’s the deal. Walnut logs, like the one shown in the first photo, have a rich, chocolate-colored heartwood and light vanilla-colored sapwood. The contrast is stark and to those that want all dark heartwood, the light sapwood is seen as a defect, something to be removed or hidden. But removing it can be costly to mills in that they will be discarding the outside of the log, which usually has the clearest lumber with the fewest knots. Additionally, the sapwood can be inches thick, and not using it results in a loss of board feet production. So, to make the sapwood more acceptable, mills use a separate process to steam the lumber after it is cut to darken the sapwood.
When I say “mills”, I mean larger production mills, those that are focused on efficiency and willing to spend the money to steam the lumber. At smaller mills like mine there is no steamer and much of the sapwood is removed on the mill. If a piece of lumber has a significant amount of sapwood, I usually grade it lower because I know it is less desirable.
In this steamed walnut panel, the sapwood can be seen as a lighter stripe down the middle.
The steaming process, as shown in the second photo, makes the walnut lumber more uniform in color – but at a cost. The sapwood does darken, but at the same time the heartwood lightens and the entire board turns to a washed-out gray color. Compare this with the walnut heartwood that is not steamed and is usually a medium-dark brown which will lean in color towards red, green, or even purple.
The idea of steaming walnut (at least my guess) must have come from sawyers that milled walnut on a regular basis. They surely noticed that when walnut logs sat for awhile before being milled that the sapwood would begin to darken. In these types of logs, much like the third photo, the colors can become quite homogeneous. In some cases it is difficult to distinguish between the heartwood and sapwood if the logs are milled at the right time. Somewhere along the line, this natural process was forced along with steaming.
This sample was not steamed, but the log sat for months before milling, causing the sapwood to darken considerably.
Steaming, as mentioned before, is a separate process. Lumber is milled, then put in “dead” stacks (without sticks to separate the lumber), and then put in a steam chamber. After steaming, the lumber is stacked with sticks and put in a kiln to dry.
I have met many customers that were under the impression that the kiln changes the color and this is not the case. The steaming changes the color. Kiln-dried walnut and air-dried walnut look the same if they haven’t been through the steamer. Just remember that steaming is an entirely separate process from the kiln.
The last thing you should know is that there is a lot of more detailed information available about steaming walnut (optimum temperatures for best color, optimum timing, etc.), but most of it is geared to those that are actually doing the steaming and can get boring in a hurry. Since most of us won’t be steaming our walnut, I think it is best to stop here.
Walnut steamer at Mueller Brothers Timber with walnut just unloaded. Notice that all of the wood is brown with no light sapwood.
Doyle Log Scale: How To Determine Board Feet In A Log
(Click this image for a larger view. Click the pdf link below for a printable Doyle log scale or Doyle log rule.)
Doyle Log Scale WunderWoods pdf
Many times customers will call to discuss having a log milled and how much it will cost. The answer is often based on how many board feet (12″ x 12″ x1″) will be produced. So, the first thing I ask is, “How big is the log?” Usually the answer is, “Well, I can’t get my arms around it.” And, while this may be helpful, there is a more accurate way to determine the size of a log and how many board feet will be produced.
There are three common scales or rules used in the industry (Doyle, Scribner, and International), but the Doyle scale is the most commonly used around the St. Louis area. All three of the scales estimate logs closely in the medium to larger size range, but the Doyle underestimates footage on the smaller logs. Because of this, it is advantageous for buyers of logs to use the Doyle scale to make up for extra log handling on small logs. Since the buyers like this scale, it is what they use and therefore, what the sellers use.
Doyle folding log rule used by most log buyers in Midwest
All buyers have a Doyle scale on them at all times, usually in the form of a folding rule with the footage marked at each inch. The printable version above has more increments on it, but it is basically the same and is used in conjunction with a tape measure. I always have a tape measure on me, so I usually use the printed version (they are also cheaper).
The formula for the scale is based on a tapered cylinder, milled with a 1/4″ kerf. Straight logs, with little taper and cut on a thin-kerf bandsaw will yield more lumber than the scale predicts. It usually averages out, because logs are usually not so perfect, and often have boards that are below-grade and end up in the firewood pile.
To use the scale, first measure the average diameter of the small end of the log inside the bark (in inches). Locate that row on the scale. Next, measure the length of the log (in feet). Move over on the scale to that length column. Where those two measurements intersect, you will find the board footage for that log. The process must be repeated for each log. Deductions are made for defects, like rot and curved logs.
Since sawmills usually charge by the board foot, this scale will help you determine the amount of lumber you will have and what you can expect your bill to be. Make sure to accurately measure your log and not just guess the diameter. The logs seem bigger than the actual measurement. My customers are usually off by about a foot in diameter on good-sized logs when they guess.
A little perspective on log sizes:
• A respectable diameter on a hardwood tree is 20″.
• A large diameter on a hardwood tree is 30+”.
• The smallest diameter most hardwood mills buy is 13″.
• The largest logs I get on a once-a-year basis is about 45″ diameter (8′-10′ from the ground).
• The largest hardwood I have ever milled is a 54″ diameter (20′ from the ground) Burr Oak.
New 100-year-old cherry; It is (no) lye!
Some woods stain great – some don’t. Oak, walnut and elm come to mind as the great ones. They stain easily and consistently, with no blotches or uneven color. On the other end of the scale are woods like maple and cherry, which are also consistent – consistently frustrating. Hard maple is the worst of the worst, with some of it taking almost no stain (I compare it to trying to stain a piece of glass) and other areas, like end grain, sucking up all the stain in the can. Anywhere that the grain simply changes directions is a spot for blotches to show up.
Right up there with maple is cherry. Although you can get some cherry boards to stain perfectly, many will look like a first-grader did it (and not the one first-grader that pays attention in class). The other problem with cherry is that it is usually expected to be at least medium-dark, which means the wood has to be darkened up somehow. I have a few recommendations for hard-to-stain woods, but for cherry, I have a trick. If you know it, don’t say anything yet.
This secretary was made from curly cherry and darkened with lye.
I don’t remember where I first heard of it, but I was told that lye darkens cherry. That’s right, lye, like the soap or Drano. I didn’t know anything about lye, so I did a little research. And, after using it many times, I can tell you that a little research is all I needed. It is amazingly simple and produces awesome results.
If I want a nice medium to dark cherry and don’t need to match a specific color, I will use lye before anything else. Lye is great because it does in seconds what would happen naturally in a very long time. It chemically changes the color of the wood, allowing all of the figure to show through without blotches. The new color created by the lye also goes below the surface to provide a measure of safety when sanding between coats of finish.
I use Red Devil lye (drain opener), which has apparently been discontinued. Lowe’s carries a crystal drain opener that is 100% sodium hydroxide (the active ingredient) or lye. I, however, have never used this product, so I cannot attest to its effectiveness.
To use the lye, simply mix with water. I use about two tablespoons to 16 oz. of water as a starting point. Test on a sample cherry board to see how dark it comes out – the change will be almost immediate. Add more lye to darken the color or more water to lighten it. To apply, use a nylon brush (natural hair brushes will melt away) to saturate the surface of the wood, keeping a wet edge and let it dry. That’s it.
Handle the lye mixture with caution and follow the safety instructions on the label. Specifically, wear rubber gloves and safety glasses, and make sure you have adequate ventilation.
Treat the wood as if you were using a water-based stain, by raising the grain before applying the lye. After the lye is dry, the wood can be finished and requires no treatment to neutralize the lye. I like to apply an oil finish before the topcoats to make the surface shimmer and really show off the magic of the lye.
No matter how you finish the piece, I think you’ll be amazed at how easily and quickly you can have a piece made from new 100-year-old cherry!
Sanding White Pine: Avoiding A Sticky Situation
I love, love, love Eastern White Pine. First of all, I love the way it smells – it can make even the nastiest of shops smell like new. I love the way it cuts –it cuts great on the sawmill and in the shop. I love that it’s lightweight – even, the widest boards are easy to handle. I love that is dries flat – most boards can just be run through the planer without any flattening. I love that it is soft – I can work it with hand tools and enjoy every minute of it. I love that when it starts to decay it gets lots of bugholes and blue-stain – it’s great for rustic work. I love that it makes great planer shavings – I want to roll in them just like the animals that use it for bedding.
There is, however, one major problem with white pine, especially air-dried white pine. It’s name is pitch. Pitch is the sticky transparent yellow goo that can ooze from the boards. In lumber that has been kiln-dried at high temperatures to “set the pitch”, this is less of a problem. As long as the lumber stays cooler than the temperature that the kiln was run at, the pitch will remain hard. But, once that threshold is passed, the wood starts to get sticky. And, since air-dried lumber hasn’t reached a very high temperature in its life, the stickiness is almost immediate.
Now, couple this setup with a large job and large boards and a lot of surface to cover with a power sander and you have a recipe for potential disaster. In fact, some air-dried white pine will be so sticky that you’ll start to wonder if there is enough sandpaper in the world to get through the job. There is, of course, a secret to working with white pine and an orbital sander. The secret is turpentine or mineral spirits.
I read somewhere that turpentine is made from pine trees, and I figured if it came from pine trees, it should be a great solvent for pine pitch, which also happens to come from pine trees – and it is. A rag dampened with either turpentine or mineral spirits will clean the pitch right off of a sanding disc or off of lumber where it has built up. To make it work in an almost automatic mode, I keep a sacrificial rag next to me soaked in the solvent and simply run the sander on the rag when it gets clogged. Just a few seconds running the sander on the rag makes the sandpaper look like new.
As I now get ready to sand a project that is all white pine, with wide boards and big, pitchy knots, I know the first thing I will do is get out the mineral spirits. Hopefully, this lumber cooperates and I won’t need to use it. Happy sanding to all!
For fun, I have some photos of the wide white pine (up to 20″) being used for shelves that inspired this post.
White pine was used for these closet shelves.
John Stevens and Scott use the bandsaw mill to resaw wide white pine for the cabinet backs.
What’s Going on at WunderWoods
Everyone always asks what I do. Here's the answer. Click on the photo above for a short video tour and see all of the steps it takes to go from a tree to finished furniture.