Monday, November 14, 2011

Natural Wood Building Blocks

I thought I'd start this post with a public service announcement:

No trees were harmed in the making of these blocks.

No, no, that wasn't it.

I am, by no possible scope of the definition, a woodworker.  

And, I'm not so sure this was such a great project for an almost 6 mos pregnant lady like myself - too many contortions required by my less-than-mobile body!

Now that that's out of the way... I'd seen some cool, natural wood blocks in a catalog awhile back and loved them, but thought they were a little pricey.  Then, my friend had a black walnut tree taken down on her property and said she had some fairly good-sized branches left and my mind started ticking.  So, I decided to make these to enter into an auction for our local chapter of Wild Ones, a native plant organization that I am involved with. 

There are several other blogs that talk about how to make blocks like these, including "Life on Willowdale" and "Home in the Country".  They both left the bark on, but for these I decided to try to remove the bark partly because it was fairly covered with lichens and also because of the nature of black walnut wood - it has really cool striations of the darker heartwood and lighter sapwood that I hoped would show better with the bark off.  (And, let's face it, because I like to make things harder on myself than necessary.)  There is also a Google Doc from the State of Minnesota DNR and Project Learning Tree that has some useful information in it. 

Here is roughly the process we followed:
1.  Collect the wood.  We started with several branches, each about 6' long and ranging from about 2 1/2" at the base to 1" thick at the tip.

2.  Remove the bark (if desired).  I used a 1" chisel to do this.  (I actually wasn't that successful in this - although it still ended up looking pretty neat - on a lot of the pieces the very innermost layer of bark remained.  For more information on the tissues in a tree branch, check out this site.)  If you remove the bark, then you should sand the branch smooth before you go onto the cutting step.  Start with course sandpaper and then work your way to fine.  (I used 60, 100, and then 150.) 
Branch with bark (mostly) stripped.
Branch after sanding.

3.  Cut the branch into your blocks.  Try to vary the cuts so that you get a variety of different lengths and widths for your blocks. I used a compound mitre saw, but you could definitely use a hand saw.  Sand the cut edges so that no rough spots remain.  I used a coarse and then a fine sandpaper. 

4.  Dry the blocks in an oven set at a very low temperature (200 degrees or lower) for a period of 2 to 5 hours.  To do this, place a wire cooling rack on top of a metal cookie sheet, then add a piece of parchment paper to the top.  Put the blocks on this set-up and periodically rotate the blocks.  Because I'm a geek, I also weighed a couple of the blocks every half-hour - they lost about 10% of their mass by about the 2 1/2 hour point and then stayed pretty consistent for the next hour so I turned off the oven then.  It will be interesting to see if they crack over time, though.
Our drying set-up.

5.  Re-sand the blocks, if necessary.  I noticed that the drying out process seemed to roughen my edges a bit so I did a quick sanding job.

6.  Coat with a protective layer.  I used a jojoba oil/beeswax mixture that I bought a while ago from Jupiter's Child on Etsy.  (I also bought an adorable carved wooden squirrel for our nature table - they have some really cute things!)  I think you can make your own using olive oil and beeswax (or jojoba oil, which smells amazing, if you can find it).  Rub the wax/oil mixture onto all the surfaces of the block.  (An aside: Rub the mixture into your hands.  Ah!)  Let sit for at least an hour then buff off with a smooth cloth. 
Blocks coated with the oil/beeswax mixture.

7.  Play with your Natural Wood Building Blocks!

A Few Thoughts: 
  • Start with a branch that is at least 2" thick at its base; 2 1/2" to 4" would be even better.  If you do decide to strip off the bark, then you will lose some thickness there and it is nice to have a diversity of sizes in your blocks.  (Mine were a little too uniform.)
  • While I like the look without the bark, bark removal is not an easy process and added at least a couple of hours to the process, between de-barking and sanding.  If you do decided to remove the bark, realize that some types of trees are much easier than others to remove their bark.  Also, I've heard that it is easier to remove bark in the spring when the sap is running.
  • Obviously, the sawing part of this process is not appropriate for young children.  I used a small hand sander for most of my sanding (a Dremel would probably have worked even better!  Can we say Christmas List?) but if you do the sanding by hand then kids could help there.  They also would be great coating the small pieces with the wax/oil mixture.  Sydney helped me carry stuff out to the barn but, luckily, she is terrified rather than intrigued by the loud saw I used, so she vacated shortly thereafter.
  • Air-drying is really probably the way to go, but it requires a lot of patience.  My understanding is that it takes about 1 year/1 inch of thickness of wood, depending on the warmth and humidity levels of where you store the wood.  I have several branches left that I'm going to treat with Anchorseal, a waxy product that I picked up at our local WoodCraft store, and try to make another set of blocks next fall.
If you end up doing this project, please let me know how it turns out and, as always, if you have any ways to improve it!  (As I said, I'm not a woodworker!)  You can also add any pictures to a new Flickr group I just created, Activities with Momma Owl's Lab.

Have fun!


  1. Gorgeous! Our zoo has a lovely set of these blocks in the play room, and I've been lusting after them for years :) They have several wide, flat slices (from 20-30 year-old trees) that are fun for making tree houses, and they blocks made from branch forks, which look kind of cool.

  2. I love this post for so many reasons. First, the blocks look awesome--my little ones would love something like that. Second, after watching you QB your WRC football team to a win with a kidney infection, I have no trouble picturing you 6 months pregnant and operating a compound mitre saw...