Bending Dry Wood For L’il Gragg – The Noumenon Phase

Over my many years of teaching furniture conservation, essentially an amalgam of materials science and aesthetics with a dash of esoteric problem solving, I always emphasized my conception of Synthetic Thinking.  By that I meant employing/combining, or synthesizing, both the observable physical effects of doing this-or-that, along with the unobservable — ideas, knowledge, speculations, hunches, theories — roaming around inside our heads.  In bringing both to the problem we would be synthesizing the Phenomenon, that which can be observed, with the Noumenon, that which can only be contemplated.  I am reminded of the opening lines to historian Paul Johnson’s monumental work Modern Times, a history of the 20th century.  As Johnson remarked, as I recall but it’s been a number of years since I read the book, Hiroshima and Nagasaki proved that Einstein’s theories were no longer just theories.

For now I am in the “Noumenon” phase of addressing the problem of steam bending dried wood.  The Phenomenon phase will come soon enough as I put those noumenon contemplations to the test in reality.

For starters, there is great doubt as to whether kiln dried wood can be re-moisturized exactly as the wood was before it got dried, or whether it can only be conditioned to mimic green-ish-ness for the purposes of bending the wood.  I suppose the chemical thermodynamics of re-integrating water molecules into or in between the wood fiber molecules could be accomplished, as my late friend and colleague Mel Wachowiak used to comment, “With enough force you can pull the tail off a living cow.”  For now all I am trying to imagine is mimicking the effects of that integration.

So, how do I best get water into the wood to make it “green” again?  (This may be the only time I will ever utter any desire to make things “green.”)   There are many considerations to test out, but the point is how do I, or can I even, get water back into the wood to affect its behavior under the conditions I want, i.e. steam bending dried wood?

Merely soaking the wood in water is a place to begin conceptually, but by itself I surmise this to be a low efficiency way to approach the problem.  Example: when I was trying to ebonize some tulip poplar to see if I could use it as banding for my tool cabinet, I soaked some 1/4″ pieces of the wood in a bath of India ink.  Since the ink was waterborne shellac with a carbon black colorant, I could discern the effectiveness of the penetration by simply sectioning the wood and see what happened.  What happened was that two weeks’ soaking submerged in the bath yielded a penetration of less than 1/16″.  Though the objective was entirely different then than now, the memory of that exercise makes me less optimistic about that approach for re-moisturizing wood as a precursor steam bending.  True, moisture diffusion in tulip poplar is not the same as with oak, whose moisture transport is much more dynamic.  Even the oaks are dramatically different in their moisture transport, with red oak being much more transparent to moisture transmission than white oak due to the comparatively open cell/fiber structure.

Even so I considered several ways to enhance the introduction of moisture and came up with a few ideas to test out.

Modifying the Water

What could happen if I could make the water into something better?  How about if I —

Make water wetter?

If I could make water wetter, in other words to increase its capacity for infiltration into the wood, I just might have something.  Well, the two methods I have at my disposal for making water wetter involve reduction the surface tension of the water, to make it wick or flow better into the substrate more aggressively than it would on its own.  The two methods are to 1) add surfactant, and 2) add solvent.  In the first case simply adding some detergent or soap would greatly reduce the surface tension of the water and let it soak in more deeply and more quickly.  In the second, adding water miscible (compatible) solvent like ethanol or propanol would do the same thing.

Increase surface area for better penetration

Regardless of how the water is modified, it is, I think, an undeniable proposition that giving it a greater surface area in which it does its penetrating magic is a winner.  The question is, how do I go about that?  I could easily multiply the surface area by dragging the surface over a bandsaw blade but that simultaneously imparts a multitude of cross grain irregularities, which would serve as a focal point for fracture origination.

But, how about increasing the surface area with along-the-grain striations?  Something as simple as quickly working the surface along the grain with a toothing plane would increase the surface area by some factor approximating 2X.  I think I’m liking this noumenon.

Or, changing the chemistry/structure of the wood on hand – ammonia gas at pressure, surfactant/fabric softener lubricity

I do not have either a pressure/vacuum chamber adequate for the chair pieces, so that isn’t even something to really contemplate.  Maybe some day, but not this day.  Besides, I do not expect to ever possess gaseous ammonia.  Because.  Besides, when using ammonia to facilitate bending wood there could be a lengthy off-gassing period.

On the other hand I do have fabric softener in the shop.  I cannot pretend to possess a full understanding of how that would work but the product’s main functionality is to “fluff” fibers through ionic interactions, but also, more importantly, penetrate into fiber bundles and impart lubricity.  Sure, wood fibers are not identical to textile fibers but they just might be close enough to do the same trick.

Quote David Bowie

How about some p-p-p-pressure?  Or its inverse?  As I said earlier I do not possess a vacuum/pressure chamber to force the water in or suck the air out, resulting in the wood sucking the water in, while this is a definite winner it requires technology I do not possess.

Use bending straps

Bending straps are a routine part of the equation when I’m bending full-scale Gragg parts, generally somewhere in the neighborhood of 1-1/8″ x 5/8″ in cross section.  Since the Gragg chairs are always painted I just screw plumbers’ straps in the necessary places and get going.  But for the L’il Gragg the pieces are only 1″ x 3/8″, with a bending cross section only half as much.  I really hope to bend these without straps but will use them if needed.

Exploit Thermodynamics

In its most basic and fundamental applications, thermodynamics is the study of energy (applied to some function) x time (that the energy in applied).  At our level of work we can assume some general inverse relativity; more energy means less time, more time means less energy to accomplish the same task.  This may or may not work here as there are activation energy thresholds.  But what about changing the formula for steam bending from 1 hour per inch of wood to 2 hours, 3 hours, X number of hours?  It might just work, but my steam generator only holds about 1-1/4 hours of water.  If I take a lengthy trip down this theoretically sensible route, I would have to devise a whole new water heating/steam delivery system.  That strikes these lazy bones as non-optimal.

Using different wood (harvest new trees)

It could be that in the end none of these options, individually or in concert, will do the trick.  In that case, fire up the chain saw and reach for my bag of wedges and the froe.  It’s about time to continue work on next winter’s firewood harvest so maybe that’s the route.

But not until I gather some phenomena.