Glaze Development Assignment: Step one
Make fifteen (20) glaze test tiles 2” x 4” x 1/4” and seventy
five (75) 2” x 2” x 1/4” tiles. Make one side smooth to allow
for labeling. Take care in handling and drying the tiles to keep them flat.
When leather hard or dry, lightly soften the edges. Bisque fire when dry.
Choose 3 published glaze receipes, looking for one glossy (shiney), one satin and one matte. All should be listed for cone 9 although glazes listed for a range of cone 8 - 10 are fine.
Show the recipes for all three to Curt for a check on availability of materials or other issues.
Using the marking stain, label the back (smooth side) of two (2) of the 2”
x 4” tiles with the full recipe for the shiney recipe; repeat on separate
tiles for the satin and matt recipes. You may use abbreviations but take to
make sure they can be deciphered latter (e.g. Don’t use BC for Ball Clay
– that could also be Barium Carbonate. Use chemical notation where it is
shorter, e.g. BaCO3 is shorter than Barium Carbonate). Take care in handling
the tiles after labeling to avoid smudging the markings.
Fire all the samples for each test in the same firing, i.e. all the feldspar substitutions in one firing and all the flux substitutions in the one firing. Ideally, you shoul place each of the two (2) tiles for each glaze type in different parts of the kiln to test for glaze variability to temperature and atmosphere variations.
Mix sample amounts of each recipe (50 grams is small enough to not be wasteful and large enough to avoid errors in measuring) and apply each glaze test to the two (2) separate tiles.
Fire the tiles in a cone 9 reduction firing.
We will examine the samples in class to discuss the results and choose two samples for the next step.
Glaze Development Assignment: Step two
Prepare one additional tile with your chosen base glaze to check for consistency. Prepare 3 additional sets of tiles (6 tiles in total) using a different substitution from the list below for the main feldspar; i.e. if your glaze base uses Kona F-4 feldspar, chose three other feldspars from the list other than Kona F-4 to substitute. You substitution should be inthe same amounts as the original feldspar.
Custer feldspar
Kona F-4 feldspar
Nepheline Syenite
Spodumene
Cornwall Stone
As a separate test, prepare 3 more sets of tiles (6 more tiles in total) using a different substitution from the list below for the main flux in your base glaze; i.e. if your glaze base uses whiting, chose three other fluxes from the list other than shiting to substitute. You substitution should be inthe same amounts as the original flux.
Bone Ash
Dolomite
Lithium Carbonate
Magnesium Carbonate
Strontium Carbonate
Talc
Whiting
Wollastonite
Zinc Oxide
Mix sample amounts of each recipe (50 grams is small enough to not be wasteful and large enough to avoid errors in measuring) and apply each glaze test to the two (2) separate tiles.
Fire all the samples (there should be 13 in all) for each test in the same firing, i.e. the base retest, all the feldspar substitutions and all the flux substitutions in the one firing. Ideally, you shoul place each of the two (2) tiles
for each glaze type in different parts of the kiln to test for glaze variability
to temperature and atmosphere variations.
Fire the tiles in a cone 9 reduction firing.
After firing, we will examine the samples in class to try to determine the effect of the substitutions on the base glaze.