Lili Krakowski on thu 24 mar 11
One of the more puzzling aspects of Life as Lived on Clayart is the =3D
business
of glaze.
Yes. Glaze.
Some people "love" pretty glazes, "love" glaze recipes, "love" =3D
receiving
a firing schedule for their digital kilns....but that's it. Finis. If =
=3D
this quick and easy
approach does not work tears, complaints, and accusations clog the =3D
list.
Lots of articles and books present pix of glorious glazes, along with
recipes. These glazes did not just leap from the authors' brains onto =3D
their
pots.
There were years of learning about glaze materials; months, if not
years, of concocting and testing glazes. And learning about what goes
wrong, why, and how to fix it.
But, somehow, many consider applying oneself TO glaze useless, a
waste of time.
So they buy ready-mixed glazes, expecting /demanding
perfection and bliss on the first try. As even
ready-mixed glazes require testing,care, discipline, order, in use,
angry disappointment results.
No one who buys a cake mix assumes one empties the box, and the thing
is done! "Everyone" accepts that directions need to be read and =3D
followed.
That if the box says add two cups of milk and one third cup of vegetable =
=3D
oil, that
is what is intended--two cups of chicken broth, and one third cup of =3D
sesame=3D20
oil
will not achieve the desired/expected brownies. And all that business =3D
about
mixing for two minutes, and baking in a specified size form and on and
on...ALL that is necessary/needed for happy outcomes.
Why not accept that something like that applies to glaze? That certain
procedures should be followed, rigorously, properly, if success is =3D
wanted?
1. Glazes are designed for certain temperatures, and, often, certain =3D
firing
methods/styles. These are to be taken seriously. Followed.
2. Glazes have to fit properly, fire properly, on the clay body to which
applied.
One must test. Ideally, IMO, one tests recipes on three clay bodies
designed for one's desired firing temperature. This will indicate if =3D
THAT
recipe will work on THIS clay body. Not all recipes will. If and a =3D
recipe
does not work on one's regular clay body, having tested on others will =3D
show=3D20
if the problem is with the glaze, or the body.
4. Glaze recipes are finalized around certain materials. Materials are =3D
not
universally identical, nor consistent, and a feldspar sold under a =3D
certain
name probably will NOT be identical to that feldspar sold under same =3D
name
five years ago.
And, a "potash feldspar" available in England or Holland will not be
identical to a "potash spar" available in US.
When a recipe calls for Potash Feldspar all one can be
sure of is that it calls for a fair amount of potash. Just that. One =3D
must
test. Seger formulas help a lot, but they are not magic bullets.
5. Glazes need proper application. The basic books all give =3D
instructions.
Sophisticated tools are fun, but let us remember that Lucie Rie applied =
=3D
her
glazes with cheap brushes from Woolworth's. (For the young'uns W was a
five-and-dime store chain, one of whose stores made history during the
Civil Rights Movement.)
Each application method must be learned. Brushing dipping, pouring. all =
=3D
need
practice . So does spraying.
And proper hygiene is needed even for "just practice"-- mask should be
worn, etc.
It is extremely puzzling why people who practice and practice their golf =
=3D
swing, or casting a fishing line feel insulted when one suggests that =3D
making and=3D20
applying glazes demands the same kind of practice.
My suggestion for learning glaze application is that one uses either =3D
glaze=3D20
meant to be scrapped, or mix a concoction of clay and silica. Most =3D
glazes
are made of non-plastic materials and little clay, so a mix of silica =3D
with=3D20
7% clay and 2% bentonite should work.
I might add that glazes with a lot of clay are easiest to use. But
some recipes include as little as 2%. One must learn.
Gather up rejected bisque. If you have none, clay flower pots
will do. But you probably have pots undeserving of immortality, bisque =
=3D
that has chipped or cracked. etc.
Wash that bisque as you would a "real" pot. Set aside. Dry to barely
damp.
Next, glaze the bisque by the method you are practicing. Do ten, =3D
twenty=3D20
pots. Check and double check for proper thickness on the pot. As a=3D20
generalization, most glazes are best at the thickness of heavy cream, =3D
and applied
the thickness of a US penny. ( Heavy cream is slightly thinner than =3D
double
cream. )
When you have done, rinse all glaze thoroughly off all the pots. Save =
=3D
the=3D20
glaze.
=3D20
Let it dry back down to proper consistency--which may
take several days. (I use a kitty litter pan for this---large surface =3D
for
evaporation) and try again. You have practiced enough when you feel
confident, easy, in this method.
When you were testing [!!!] each new glaze to begin with,
you, you dipped your test tile once, twice, three times into the test =3D
cup,
achieving three graduated thicknesses of applied
glaze.. By the time you are in the whole-glaze-bucket business, you =3D
have an
idea of what you want the slop
to be like, so that one coat of proper thickness does it.
Not all glazes work well at all densities. Some "want" to be thick
fluids, others "want" to be very thin. High clay glazes generally =3D
prefer=3D20
thick, high spar and frit ones (few plastics) thin.
There are several common tests for proper glaze-bucket slop thickness.
We used to use a finger test.
The finger was dipped into the glaze bucket, given a shake to remove =3D
excess,
and the finger "examined". The skin should be covered, the nail showing =3D
in=3D20
outline, but details such as cuticle
obscured. I do not know if this test still is used, as current safety =3D
rules=3D20
may, in fact,ban immersing one's bare hands in glaze.
=3D20
An experienced potter can gauge the proper density simply by pouring the
glaze from a ladle or cup. See "heavy cream" above.
One also can buy --at the paint store --a little metal cup with a hole =
=3D
in
it. This is used by painters to check the thickness of paint they =3D
want to=3D20
use. One fills the
cup and then counts
or otherwise measures how long it takes for the cup to empty. So, ideal
thickness for Glaze A might
be a count of three, and for Glaze B a count of five. One easily makes
such a device.
Hydrometers work very well. Eccentrics actually buy them! The rest of =
=3D
us
make'em Th purpose of using a hydrometer is to insure that the slop =3D
thickness
from bucket to bucket of same glaze is consistent. A hydrometer is =3D
especially
useful when glaze has sat around in its bucket a while and lost some of =
=3D
its water.
The hydrometer allows one to reconstitute the slop to previous fluidity.
One can weigh down the wider end of a wooden chopstick --glue some =3D
stripped
metal nuts on, some beads, a ball of plastic
putty--and toss it in the bucket when the glaze is "just right" for what =
=3D
you
plan to do. Mark the line where the fluid came to. Make one stick for =3D
each=3D20
glaze.
Or you can use a ruler, or notch regularly spaced marks on a =3D
weighed-down
stick, record what line was right for which glaze, and use one =3D
hydrometer=3D20
for all.
My own hydrometers are 3" x 1.25" orange plastic pill bottles. I put
pebbles, or stripped screws,
even foreign coins in them. When the slop seems right to me, I float
one of these bottles in the bucket, adding weight till it sinks to the
bottom rim of the cap. I then make
out a label, put the label in the pill bottle so I can read it, and glue =
=3D
the
cap on.
_________________________________________________________________________=
=3D
___
Lili Krakowski
Be of good courage
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