Steve Slatin on thu 17 dec 09
. the great handmade battle was ended, if not over ...
So I thought, hey, why not try posting something that's
actually, like, clay related?
Well, there's two things on my mind. One, possibly of
interest to some, is acquisition of a new scale. (The old one,
with some 7 years of service, was recently knocked off
of a stack of glaze buckets on top of the glazing
table, and landed directly on the concrete floor.
This was not its first fall, more like it's 4th or
5th, but for the first time the scale began to react
somewhat erratically.) Needing something in a hurry,
I picked up a "Home Exclusives Electronic Kitchen
Scale" at Rite Aide for $10.
I had quite a few "known weight" objects, and was
able to use them to check the unit's initial accuracy.
It seemed pretty good, with only one test item (a
4 g one) being off from previous scales. It also
survived the test of uniform multiplicity (2, 5, and
10 identical objects of known weight giving results
to within 1/2 percent 2, 5, and 10 times greater than
the individual unit weight) again, with the exception
of the lowest mass items, where at 10 times it was off by one
gram (or, possibly, spot on, but revealing a rounding
error previously undiscovered).
It's spec'ed by the mfgr as plus or minus 7 grams out of
5 kilograms, and it may actually be close to that good.
Precision one gram, or fractional oz (I didn't check this).
I'll still use more precise scales for that 3 gms of
cobalt or whatever, but for the big stuff in the recipe,
this is a useful unit. Build quality appears adequate.
Come with a 'bowl' of plastic but you can tare out a
small bucket or whatever. Batteries included.
FWIW, I believe the days of triple-beam balances being
the standard for glazing are over. This is what industrialization
is supposed to bring us, a product that's reliable, meets
a need, and cheap.
Also -- I just glaze fired my first experimental pieces
using Dave and Matt's "Porcelain for the People." The sample
box is $30 for 30#, which gives you a good quantity to
experiment with. My observations are based on throwing
three pugs in sequence, one of B-Mix, one of OH-6, and
one of P4tP and firing test pieces from each.
P4tP felt softest out of the bag, OH-6 the stiffest. All
three were fine after spiral processing (which the
cognoscenti insist is not 'wedging'). B-Mix appeared
the most susceptible to sudden collapse when deliberately
throwing too thin; OH-6 and P4TP were about the same in
behaving more like a stoneware while throwing.
All three had good lift, with P4tP being the best, and
OH-6 and B-Mix about the same.
I threw various shapes, all survived drying and trimming --
only B-Mix had an s-crack issue (just one pot). At the
leather hard stage, P4tP was noticably smoother to the
touch than the other two clays.
I threw one more small pug of P4tP without spiral
processing. I had real difficulty with this, in fact,
it was hard to cone it. For comparison, I tried OH-6,
and it responded quite well after coning about a half
dozen times, which it took to well. (I will try to
repeat this experiment -- it may have been an alignment
thing or something similar.)
After bisqueing, P4tP was the smoothest, OH-6 had the
most tooth, B-Mix was in the middle.
All three behaved normally in glazing and glaze firing;
again P4tP seemed the smoothest on the unglazed portion.
It also 'polished' better with a flap wheel.
My glazes all responded well with all three; I have
not yet tried the most troublesome glazes with P4tP.
Raspberry Red, Gnu Blue, Ron Roy's Licorice, all came
through fine and had color very similar to OH-6, and
not far off from B-Mix. I will try some glazes that
are white or transparent next and see what the
color responses are. This will give me an opportunity
to evaluate translucency.
I also need to do an unglazed test chunk for vitrification
testing. But that will be well into the new year.
Other notes -- the delivery on this is great -- I placed
an order one night, and two days later it was at my door.
It's a clay with a nice feel to it, and it seems to be
quite predictable in handling -- just don't skip the
spiral or ram's head processing. At the sample price
it's a bit expensive, but I'm hoping that it can be
acquired through more normal means -- larger shipment
by truck, or local dealer.
Steve Slatin --