Hello, I am new to this list and as an intro to myself I include a few
thoughts from my twenty years experience as a potter in New Zealand. I also
have deteriorated eyesight to a point where I called it 'impressionistic'
and as a consequence have excellent hearing. I am only six months into the
'Arts of the Shakuhachi' but love to play it every day, usually several
times a day, and am starting to make some from bamboo that is growing in my
backyard. I have had some success and respect the challenge.
Clay has some interesting similarities to wood, here are a few thoughts I
have had.
Clay shrinks as it dries, from wet clay to fired vitreous (matured) there is
up to 18% shrinkage, 1/5th.
Clay will crack if it dries unevenly. if one area is thick while another
thin, the thinner area will dry and shrink faster and crack.
Clay is porous until vitrified or glazed, some clays are finer grained and
less porous, clay may be 'burnished' to reduce its porosity.
A glaze is designed to have the same expansion/contraction coefficient as
the clay body, if these are too different the tension between the two will
cause the glaze to crack or peel off the clay body.
The more dense a clay, the more resonant will be its sound, 'ping' a ceramic
bowl or cup with a flick of your finger and you will hear a 'ring'. The
sound given may indicate the existence of a fine crack by giving a 'fine'
rattle in the sound, or the sound may be dull due to water absorbtion.
Porcelain is much denser than earthenware and gives a finer, longer 'ring'.
The thickness of the clay also affects the quality of this 'ring'.
In my short exploration into making a bamboo flute I have referred to those
qualities in clay.
Bamboo has a skin, like a glaze, I am sure that nature has provided an
excellent expansion/contraction relationship between the skin and the inner
bamboo wall, but this must be influenced by the cutting of the bamboo, the
opening of the cells and the drilling of holes through the wall.
Localised heat is generated when drilling and sanding, could this initiate
an eventual crack, such as down the outer wall along the line of holes ?
If the inner wall swells with moisture, could the skin crack, being unable
to expand with this swelling ?
If the skin is subject to excessive heat, such as sunlight, this would
surely result in stresses ! Especially if the inner lining is a hard resin
and has no flexibility !
How would a piece of bamboo respond to being 'kiln-dried', say at 110 C for
five hours ?
A denser, harder bamboo is going to be more resonant than a softer, less
mature bamboo.
What are the influences on resonance by oiling or burnishing, oiling the
inside or the outside of the bamboo ? Do some oils soften rather than harden
?
And what about all that saliva ? Is it unevenly distributed along the bore ?
Well, I have been stimulated and have other questions that I will bring up
in their own threads.
Since joining the group I have been reading through the archives, begining
in 1997 and have found them very resourceful and entertaining. I am not
finished yet but it has been a great way to get a feel for the group. I
particularly enjoyed a series of installments on a discussion between
'Socrates and a Student', such are the ways of learning.
And about Zen ? We all live by sustenance.
Regards,
Kel.
www.rolling-cloud.eol.co.nz
.
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