When I'm throwing I'm thinking about
form, not glazes
I keep these little samples around to help organize my thoughts:
I start to arrange the pots in little piles using
ware boards - (right) 1" X 12" or 8" or 6"
The terra cotta pot on the left is for drying trimmings to be slaked
At some point one must mix the glazes
Before we go from clay to glazes we should address the idea of clay IN
Many recipes you will see contain 25 percent clay
This has many uses - keeps the glaze from "panning" AKA turning into a
rock at the bottom of the bucket with water on top.
It adheres and coheres the glaze and makes the glazed pot easier to
handle and not have the glaze flake off.
More on the subject later
(Google thixotropic in another window)
I do the measuring in front of an exhaust hood/booth to minimize dust
The material, here G200, goes from the bucket to the scale then into
the water and any
dust made goes out the fan.
You have to pay attention because it's mind-numbingly boring and if you
daydream you may forget if you put in two or three measures of an
It's pretty much basic mathematics to mix up a 1000g batch of glaze
The scale will only hold 610g at a time, max - so any component that
adds up to more than that will need to be separated into portions.
For instance, my temmoku recipe calls for 1402g of G200 Feldspar
per 2000g batch
So I add 500g, 500g, then 402g
Tony Hansen's Digitalfire
Software is a whole education in glazing
It will store your recipes in a data base print them out for use, and
he has a wonderful online reference website that will answer most glaze
If someone gives you a recipe that doesn't add up to 100% - the program
will recalculate so it adds up to 1000 or 2000 gram batches
Always add powder to liquid
If it doesn't come into solution, pour the glaze back into the pan and
Careful not to add too much water
After mixing I push it through a 60 mesh screen just to eliminate
clumps, and impurities:
This is 6000 grams of glaze - a practical amount to be moving around in
that great invention - the plastic bucket.
I mixed three bowls of 2000g each pictured above.
Some of the best glazes
in history are the simplest with few ingredients
Rhodes 32 is a wonderful glaze with a soft feel to it.
made with just these 4 materials : Potassium Feldspar 48.9,
Kaolin 25.1, Dolomite 22.5 and
( From Clay and Glazes for the Potter
1957, Danial Rhodes , Chilton )
Here's a sample of Rhodes 32:
Pot by Rick Bonomo
If you want to mix up the classic Reitz Green
are a few
"It originally was a shino until
Pete Pinnell or someone tried it with cobalt and rutile", per clayart
discussion cited above.
Don't you think Don Reitz was the one ?
You have to gather up a whole new pile of materials:
I think I want to add to this amount to make the
dipping/pouring/glazing easier, so I'll add 2000 grams
Bentonite keeps this glaze from panning, see below.
The glaze itself needs to be applied thick - so you can't have too much
water in the mix
Also, there is only 8% clay in it, so it is subject to panning
Therefore, I add 4% Bentonite, but there is a price - it clumps: big
There are a number of ways of handling Bentonite - I just push it
through the screen with the liquid glaze.
Then again "clumping" is why you add it - Bentonite is an ultra fine
clay that helps to hold the other ingredients up in suspension
Kitchen tools have lots of uses in a pottery
Just like cookie icing - mm mm
Other glazes waiting to be used
Coleman Clear, Leach 4321, Coleman Vegas Purple, MacKenzie Shino,
Cushing's Magic Black, Coleman's
The next step is to is to decide which glazes to wed to the form
They become one
I try to make little families of similar or complementary forms with
the same glaze
Now this just looks to me like it should be a pile of Celadon.
The transparent Celadon will reveal the carvings and impressions
The current undisputed Queen of Carving under Celadon is Elaine Coleman
To be Temmoku:
One of the interesting things about glazes is watching them "break" to
a different color
Classic Temmokus break to a brown where the rim is thin or other thin
Also nicely accepts an iron oxide over glaze decoration
Most potters love this sort of thing - it goes back thousands of years
to China before porcelain.
Simply Red breaks to
a nice gray over stoneware
This is Simply Red being mixed - the bentonite is slow to enter
The green powder is the copper carbonate that will provide the red
color when reduced
I like the way Vegas Red breaks over a white slip
Before glazing you may want to place under glaze stains
Below is copper carbonate under Leach 4321
I use the Giffin Grip for under glaze banding:
Over glaze decorations can be done using oxides, stains or just another
Below is a postcard from Sequoia
-a very fine potter
I usually apply Shino first:
I first check the supernatant
Since I haven't altered this bucket, since last use, I'll assume it is
the right thickness without having to remove water from the top
Our friend the paint mixer and hard wired drill
Carefully - this can make a real mess:
Then run it through a screen, again
Shino is a stiff glaze - and bubbles will show on the pot after firing
It doesn't smooth over like some glazes
One of the things I do to make Shino melt is to sprinkle
hardwood ash, like a wood flame might
Do this under a hood - don't breathe
in the ash - it's like powdered Drano - very caustic
Now I know that this (Reitz) glaze must be applied thick and if you'll
added to this batch
And I added 4% bentonite so I'm going to guess that it has gelled it up
enough that I don't need this water
So I'll remove water with a siphon
After applying the Reitz glaze I will also spray it on the other side
of the shino and on top of the already glazed pots.
On the pots to get an extra nice thick coat of glaze
On the shino to make it melt like this:
My "fancy" sink got pressed into service, since the other room flooded
Beware the steps of the Senate!
Iron oxide decoration over Shino glaze, an old, old eastern
Red iron oxide also makes a nice decoration over iron black
I've concluded that there is good reason to work with this glaze
And perhaps why some artists wear black.
It is just chock full of pigments to make it black:
Chrome Oxide, Iron Oxide, Cobalt Oxide, and Manganese Dioxide
You don't want to get this on your pretty white t-shirt
This is the Yin to translucent white Porcelain's Yang
But it finishes off the bottoms of this set which has had four previous
Shino Glaze, Ash Sprinkle (right), Reitz Green Spray (left side), Iron
Oxide decoration and now a Magic Black Bottom,
and of course under the glaze is the faceting and handle applications
They all look pretty boring with out the fire:
And I hose down the floor regularly - just to keep the dust under
Now transport up to the kiln house on ware boards:
All safe inside the kiln house and ready for the fire:
Thus concludes part two of our series.
Click The Fire
for the third
This firing scheduled for 3/20/10
Part I - The Clay
Part III - The Fire