Friday, June 15, 2018

Greenwood Fest, or, "It took me five years just to get the basics..."

"I imagined it would be quite straightforward. It actually took me five years just to get the basics."--Robin Wood.

Five years ago I built my first lathe and started on this turning journey. It has been a blast, full of mistakes and lessons and outright laughter. Do I have the basics down? Maybe, but I also know enough to sense how little I know. I have found that making mistakes early and often is a key to growth, and nothing to get upset about. After ruining a rather large beech bowl the other morning while trying to separate it from the core, I laughed so hard my daughter rushed to the shop thinking I had injured myself. It was a good lesson, about the toughness of dryish beech and the fragility of the thin base. I posted a shot of the bottomless bowl to Facebook, and comments flooded in on how I should save it--glue in a plug, turn a pedestal, repurpose it. All fine ideas, but to what end? I am all about repurposing, but am I in this to turn bowls, or to learn to plug holes in bowls? Owen Thomas's response was best: "Chuck it in the f*ck-it bucket." Get on with turning another.

For years I have learned through trial and error. How many rims did I ruin? How many times did the hook catch and the mandrel come loose? How many bowls checked while drying? Often I wished a more experienced turner was looking over my shoulder and giving tips, which is why I so enjoyed short courses over the last few years with some great turners. The pre-fest courses at Greenwood Fest gave me the opportunity to work with Jarrod Dahl last year and Robin Wood this year. Both courses were mind-expanding. There was one point last year when Jarrod leaned over and said something like, "No, turn the tool upside down and attack the rim from the other direction." My head nearly exploded. I was ready for instruction and gained a lot from the experience.

This past Greenwood Fest with Robin was no exception. Just watching him turn was a course in itself. Noticing the little things, like how he starts a rim, the way he steps the outside of his bowl, the sweeping cuts he uses on the inside, how he "cores." Below, Robin was illustrating how little pressure is needed to get the hook to engage, trying to get new turners to avoid the death grip.


I definitely learned a lot from Robin, especially about hook design. He asserted that making hooks is easier to learn than turning bowls. That is encouraging, as I plan to start "bashing out" hooks this summer.

One challenge with both Jarrod and Robin's course was the heterogeneous class, with about half the students new to this type of turning and the rest with a few years experience. It takes about a day to get the new turners sorted, which leaves little time to help the rest of us refine our work. Nothing either instructor should have done differently, (except maybe making sure the lathes were stable and running sweetly before we got there) but it definitely cut down on instruction time for the more experienced. If I take another course it will either be one-on-one or one for more advanced turners.

As with all Greenwood Fest events, a big draw is the attendees. A chance to catch up with old friends (Oliver Pratt, Etienne Vincent and Jake Peters in the turning class, Dave Fisher, Tim Manney and Derek Sanderson running their own shows), and to meet some new people, like Dawson of "Michigan Sloyd" Moore, was great. And the quiet moments, just reflecting and having a good time--sitting on the dock with Oliver, Jake and Dawson, sipping bourbon, the sun setting, watching an osprey snatch fish out the water and haul them off to her nest. Doesn't get any better than that.

Thanks to all the instructors and attendees for a great time.













Tuesday, January 2, 2018

Burning bowls

While I love the effect of milk paint, especially the way layered colors gain character through use, I have been experimenting recently with shou sugi ban.  Shou sugi ban (焼き杉), literally "burnt cedar board" or "grilled cedar," is an ancient Japanese technique of preserving wood by charring.  A more accurate term might be "yakisugi", as it seems shou sugi ban is actually a western misinterpretation of the Japanese kanji.  No matter what you call it, the burnt surface is dark, rich and textured,  especially once oiled.  It is also bug, fire and water-resistant, allowing some structures to last for hundreds of years.  You can get lots of different effects with different burn times and treatments.
https://goo.gl/fepi8s
When used on bowls, this technique can create some really striking effects.  The surface is velvety smooth and inviting to the touch.  Visually, the matte black sections seem to suck in all light, such that if you char only the bottom of the bowl, it makes the upper rim appear to float in space...




The process is pretty easy and there are lots of videos online to get you started--just burn, brush, wash and oil.  As nearly all of the tutorials online focus on burning cedar siding, I thought I would share some insights into how this technique might translate to smaller birch bowls. 

As I understand it (and I am no chemist!), charring wood alters the surface of the remaining material.  The cell walls of wood are made up primarily of cellulose, which is hydrophilic and helps draw water through the tree.  Lignin takes up much of the space within the cell walls and helps give strength to the plant.  Lignin is hard and hydrophobic.  When you burn wood, the cellulose vaporizes first as it burns at a relatively low temperature, leaving behind lignin, which burns at a higher temperature.  Thus, charring creates a hard, hydrophobic skin of lignin and carbon on the wooden bowl.  While I don't care about the other benefits of shou sugi ban (termite and fire resistance, for example), I sure like the idea of my bowls resisting wear and water!

Most videos online show people using a roofing torch on cedar planks, but that is overkill for a little bowl. I use a simple Bernzomatic propane torch, which costs about $30.


Obviously, it is preferable to work outside on a non-combustible surface.  If you are going to burn the outside of the bowl, I recommend propping it on top of an empty tin can.  No matter how dry your bowl is, as you burn the outside moisture will be driven from the inside, and it needs a place to go.  Be prepared for the bowl to warp a bit, even if it is "dry."  I have not had one crack yet, but you can see it change shape through the process. I try to keep the flame moving over the whole bowl for a bit, bringing the entire piece up to temperature before really working on one spot.  

Heat bounces.  As you approach a foot, bead or decorative cut, you will find that the heat does not make it into the valley of the cut.  Instead, it will project out and burn the surface at a right angle.  This means you can cook the foot pretty good trying to get heat into the valley between the bowl and the foot. I have learned to embrace these lighter areas.


Here you can see the light line around the base of the foot, yet heavy burning on the rim of the foot itself.  Heat bounces and does not penetrate into valleys very well. Embrace it.


The other reality that comes from this bouncing effect is that a bead can be used as a "wall" to separate a burned section from a non-burned section.  
Here the bead acted as a "wall" and helped protect the rim band from burning and proving a sharp transition.


Inscribe first, and then kiss the surface with the torch for a nice contrast.
I can also envision how one might add a design by using masks to protect some areas from burning.

If you do burn right up to the rim, be careful of thin lips.  They will catch fire faster than the rest of the bowl, and if an ember forms it can burn a notch in the lip pretty quickly.


Here you can see both a decorative cut spared from burning, which is a nice bright line, and a rim burned too much, where an ember formed and burned down into the bowl.


Once the burning is done and the bowl is cool, move on to brushing.  I recommend a nylon brush to remove the excess carbon.  If you don't remove the excess carbon now, the bowl will leave marks on surfaces later.  Just like when you sand milk paint, watch out that excess soot does not stain the rest of the bowl.  I am often surprised by how much of the luscious black comes off with brushing.  Don't worry, once oiled that black color will come right back.  


Here the bottom half of the bowl has been brushed with a nylon brush. The top has not.  No worries--that brown post-brushing color will turn black with oiling.    


The reason I like the nylon brush over a rag is that rags often leave behind fibers, especially if you rub against the grain.




I then recommend rinsing the bowl, again being careful not to let the loose soot stain other parts of the bowl. Some people blow the dust away with an air compressor.

Once dry, oiling is pretty straightforward, though be careful not to rub excess oil from the dark areas onto the lighter areas.  Here you can see the oiled wood returning to a nice, dark shade.


Here the top half has not been oiled yet, but the bottom has.  Nice, luscious black tone.   


After oiling.


I am now experimenting with chip carving burnt bowls.  The charring is not just a patina, it goes down a ways, so only the bottom of a chip reveals the unburnt wood.  But I like the effect.  I was always hesitant to chip carve painted surfaces, as the pigments dull the knife edge.  With shou sugi ban there is no such concern.




So, there you go. Hope that helps.  Enjoy and be safe.


焼け  
  "burnt bowl"

(update, 9/19: charring the interior of a bowl is also lovely and worth exploring.  I have done it on a number of bowls and it works great.  That said, watch out if the exterior of the bowl is already painted as it might cause checks, maybe because the paint alters how the exterior skin releases heat or expands.  Maybe the checks were already there before charring and I did not notice them, but worth watching out for in the future.)

(update, 11/21: After scorching, let the bowl cool completely before brushing off excess char while running the bowl under water.  The water soaks into the super dry bowl so fast that it can cause dramatic cracking!)