Sawing Walnut: Sapwood and Heartwood
Here's a discussion about the proportions of heartwood and sapwood in a Walnut log, drying methods, and the value of both for furniture, bowls, et cetera. May 15, 2012
Question
I recently had the chance to cut 6 walnut logs 8-12 inches in diameter. I have never milled walnut logs before. There is so much white sapwood that by the time I get to the brown heart, I have lost a great deal of the wood. Does one just cut the sapwood away and discard, or cut the whole log and trim the sapwood later? Is the sapwood useful for anything and when it is dry, will it stain well?
Forum Responses
(Sawing and Drying Forum)
From contributor K:
Yeah, it's tough to get nice heartwood lumber out of such small diameter trees. 18" small end would be about a decent size. Some have thicker sapwood than others, especially if they have grown out in the open instead of in the woods. I sometimes save the sapwood, but not sure how it stains. I'm thinking I will sell for paint grade stuff like soft maple. I do the same with cherry. Can't stand to see that clear lumber go on the firewood stack.
From contributor T:
I turn bowls and include the sapwood for contrast on the edges.
From Professor Gene Wengert, forum technical advisor:
Walnut is steamed just after sawing to color the sapwood. This is aggressive steaming at 100% RH to avoid any drying. Some people will use unsteamed walnut and then use a stain in finishing to darken the sapwood. Both techniques are used commonly in the industry today.
From contributor D:
I use a lot of walnut, and some has sapwood on it. I wouldn't worry about the sapwood yet. Just cut the lumber and then when it is dry, cut off sap or stain no loss in wood. But if you stain with walnut stain, the sapwood will tone down, but it is still lighter unless you stain that section again. Which may show the difference. I would only stain one time. I have made around 500 jewelry and trinket boxes and have stained some for just that reason. The same with cherry or any wood that has sapwood on it. Sometimes the cherry sap looks good - depends where it is at on the project. I would keep all the wood. Like Gene said, they steam for color all the way through the wood. I stand my wood on end and it will dry faster. I stand it as straight as I can with a little sticker at the top. I have done this lots of time over the years. I used to hang my big boards up like they hang beef in a cooler. I have not had a board warp yet. I have been doing this for 50 or so years.
From contributor A:
I haven't done a lot of wood drying but I have hung boards up like you have suggested. I always imagined boards air drying hanging under a roof. I used those big hooks you get at Home Depot and screwed into the end of the board. I currently have quarter sawn white oak hanging this way in my attic. Would like to have more discussion on this. I also came across an air drying rack photo from the 30s. They stood wood up in a special rack. The way I see it, the tree grows up, so why not dry the wood this way.
From Professor Gene Wengert, forum technical advisor:
The liquid in a wood cell is held in the cell by vapor tension and by the lack of large holes leading away from the cell. As a result gravity has no effect on the drying process. Hanging lumber does allow air on all four sides and hence you can get faster drying. There are also few sticks used. The process is called end racking and has been studied.
One person went a bit further and put the lumber in a spinning arrangement to have centripetal force drive the water out. Didn't work, but the increased air flow did have an effect.
Regarding warp, note that fast drying will result in less warp. Overall, we do have some air drying operations that are drying too slowly, giving warp, long drying times, etc. Following good air drying practices can get good drying, however.
From contributor R:
Don't worry about the sapwood. I use it in my furniture making. I do reproduction furniture, specializing in Queen Anne, Chippendale, Federal and the like. Sapwood ends up in all of my projects. I use Ace Hardware's dark walnut stain and stain only the sapwood. I use an artist's brush to get next to the heartwood and then a rag or bigger brush depending on the amount of sapwood. Here are a few projects that have sapwood in them with the process I use. I think it looks just fine.
Click here for higher quality, full size image
Click here for higher quality, full size image
Click here for higher quality, full size image
From Professor Gene Wengert, forum technical advisor:
Excellent grain matching, top and bottom on the first picture. Looks great.
From contributor R:
Thanks Gene! I wanted to make the desk in two pieces for ease of movement. Being made out of solid walnut it is very heavy. I made the sides complete and then cut them apart to make the two pieces then re-aligned them to put it back together. You can't tell but the grain wraps the ogee bracket feet as well. I try where I can to let a board wrap a corner or a transition. Just one of the details that I think make the difference between nice furniture and fine furniture. All three of these pieces have sapwood in them. It's very easy to blend it to the heartwood.
From contributor A:
During the summer I saw and dead stack green walnut out in the sun and cover tightly with black plastic. In about 3 months I uncover and sticker it. It is the nastiest stuff you have ever seen, but when it dries you see some very pretty wood. The sapwood will stain just like it was steamed. Try a little and see how it goes for you.
From contributor R:
If a person was going to cut a bunch of walnut in September, would that be too late to try your trick to color the wood? I don't mind using sapwood, but why do it if you don't have to? As soon as the heat breaks for the year I plan on cutting about 3,000 bd ft in September and I'm afraid that since I will be cutting 12"-20" trees there will probably be quite a bit of sapwood.
From contributor C:
That is great looking work. I like the sapwood and with the cost of buying wood these days, try to use every scrap. I even use old pallets for some of the things I build. It only adds character in my opinion. I have a family and money is sometimes scarce.
