Another turned-box experiment with freehand chased threads
Getting skewed up
Green Wood Blues Take 2
If you read our first post on green (freshly cut) wood , you’d have got a sense for why green wood is an interesting medium with which to work. In this post we’ll get into some more detail regarding what we have learned.
Initially, our interest in green wood had to to with the relative affordability of the medium. Green wood is essentially unseasoned firewood. If one prepares it correctly, it can become a beautiful piece of work. If not, it still works as fire wood. It’s great for learning.
What we learned from getting and processing a bunch of green wood follows:
- Cut the pith out of rounds and seal the end grain. This is a “must do” or the wood starts spitting very quickly as it dries leaving one with … firewood.
- Trim rounds or slabs into blanks (and seal the end grain). Each round or slab has one major piece in it. The trick is to identify what that is and optimize how the blanks are cut. There maybe more than one piece trapped in the piece of wood. The trick is to determine the largest and/or most desirable one and cut that out first. The rest follow.. There’s surprisingly more “waste” in this process than one would think.
- Rough turn the blanks. For platters (open forms), bowls (enclosed forms) , and vases (hollow forms), this means turning the piece so that the wall thickness is approximately 10%+ of the finished diameter. This will allow the wood to move as it dries. The end grain shrinks more than the long grain turning the round bowl into an oval. Leaving a thick wall permits the piece to be turned round regardless.
- Put the rough turned blanks up to dry and check them regularly. If the wood dries too fast, it will start to crack. In this case, one can either seal the wood using a green-wood sealer, or put it in a plastic bag filled with (green) wood shavings to retard the drying. Note that if the bag is sealed, there’s a chance the wood may start to rot or spalt. If the wood is too wet, it will start to have surface mold. In this case, the wood needs to be moved to a dryer environment. It’s also possible to seal the blank with wood sealer to retard and even out moisture loss.
- Boiling the rough turned blanks can expedite the drying process and help prevent checks or cracks. Green wood has two types of water in it: bound water contained in the cell walls of the tree, and free water that the tree uses to move nutrients around. Boiling the wood (for a while) ruptures the cell walls and frees the bound water. If one allows the wood to cool down in the heated water, it also serves to “anneal” the wood by allowing the lignin that gives the wood it’s structure to relax and reset — important if the tree has stresses from asymmetric growth. This reduces the amount drying time and checking that occurs from stress. Beware, however, that if the free water is allowed to dry out too quickly there will be some checking.
If this seems like a lot of detail, it is. It is also a process that master woodworkers know intuitively, and which we are trying to learn. Some of what old times wood workers do is art. Some of it is science. And, some of what they do maybe pointless superstition. A part of the fun and challenge of what we are doing is sorting through all of the preceding to come up with our own understanding on how to work with wood.
A couple of useful resources:
- Understanding Wood by R. Bruce Hoadley
- Fine Woodworking on Wood and How to Dry it: 41 Articles
After rough turning a bunch of bowls, we decided to boil them! The idea is to rupture the cell walls, free the bound water, and expedite the drying process. It’s working so far
Green Wood Blues Take 1
Something we have learned from working with wood over the past year is that working wood takes time. That may seem odd, but there’s a cadence and a rhythm in making things with wood that one ignores at one’s peril. Instant gratification is not an option.
Recently, we have started working with green (freshly harvested, unseasoned) wood. This is a departure from the more-or-less-straight-and-flat, kiln dried wood, that we were using previously. Even with that, rushing things is not advisable. It’s unsafe. Both the wood and oneself need to relax.
So, what the difference? There are several, but here’s a little peek.
#1: Green wood is wet. It still contains most of the moisture in the tree since it’s been freshly cut. It needs to dry out, be seasoned, before it can be used — unless one wants to specifically use effects of the drying process.
Most of the wood one encounters in furniture has been kiln dried. Some of the more expensive custom furniture may have air dried wood (if it has steam bent elements, for example), but that’s increasingly rare these days. It takes approximately a year per inch of board thickness for wood to dry out. Yes. A year.
Dry the wood too fast, and it warps and checks (cracks or splits). Dry the wood too slowly, and it may spalt — i.e. start rotting. We have another post on spalting to read if you wish.
#2: Green wood offers greater mechanical and artistic flexibility. Like people, trees are all different. They have different life experiences. Trees express their experiences in their physical structure. For example, a constantly wind blown tree will have asymmetric growth rings. a wet spring will yield broader growth rings, a scar may turn into a knot or a burl. Working with green wood offers the opportunity to “read” the underlying structure and use it as a design feature for either it mechanical or aesthetic properties.
Features like knots, burls, bark, grain, and spalting (undesirable for mass produced lumber) can be quite beautiful if integrated into the design of a workpiece. To a woodworker, the opportunity is to “read” the tree’s story and cast a “defect” (or anomaly) in a way that makes the tree’s life experience into something special — think Cindy Crawford’s mole. In a finished product, the defects and anomalies can be polished vignettes of the trees experience the make a work piece special. Yes, it’s geeky, but kinda cool at the same time.
#3: Green wood costs less than seasoned wood. Think of wood like wine. There is an optimal age at which the wood should be used. Fresh pressed wine like fresh cut wood is relatively inexpensive. Most people nominally season it and use it as fire wood. Let it age and season, and … well … the price can go up significantly.
We’ve started using green wood, mostly for turning things like bowls. The benefit to doing this is we are able to find wood at a good price (or sometimes free), and learn from it. We get to learn how to highlight the little things that made the part of the tree we have unique. It also allows us to manage the seasoning process to benefit the final work product.
All of the preceding is way more detail that we thought we would ingest. It does, however, offer a connection to something real, tangible, and a world that most people never get to experience. We hope you’ve enjoyed this little peek into what we are doing. Stay tuned for more on what we are making, and how we do that.