Electric Mid&Hi Fired Ceramics
Cone 6 Glaze Testing & Reporting
Collaborate on building an online list of well documented glaze recipes, with application and firing methods. Strong photo documentation. Only glazes that are mature at cone 6 will be included.
Testing the glazes, and identifying their problems and fixing them. Also, if there are obvious issues just by looking at a glaze recipe (like high barium, insufficient clay to suspend or harden, too much feldspar (which causes crazing), too much clay (causing crawling, peeling), hard-to-get materials, non-specific materials, etc) then it needs to be fixed as part of the testing I would say.
Tony Hansen included links below to procedures for a few glaze tests that could be done. Another good one would be to appraise the rate at which it settles, how hard is the dry layer, the water content of the slurry, the viscosity, these could be measured with commonly available tools.
Links:
Richard Busch's Nutmeg as a base with other glazes layered over it.
I fired a bisqued Laguna #80 clay test ring consisting of a nutmeg base coat (brushed on) all the way around the ring and 9 glazes brushed-on in patches over the nutmeg. I am quite taken with the luscious surfaces and coloration that developed. The kiln was soaked for 1/2 hour after the kiln sitter tripped on a cone 5 1/2 pyrometric bar. I cooled under power at medium heat for an hour and forty-five minutes to 932 degrees C (overshot my 950 degree target) and soaked at that temp for an hour to develop iron reds and then shut off the kiln. The cone rack on the test shelf ended at cone 6.2 ( read that as cone 6 touching down and cone 7 pointing at 2 o'clock)
Recipe Name: Nutmeg
Cone: 6 Color: Tan - light brown
Firing: Oxidation Surface: Semiglossy
Amount Ingredient
23.3 Dolomite
23.3 Spodumene
6.8 Frit--Ferro 3134
23.3 Silica
23.3 Ball Clay--Old Mine #4
100 Total
Additives
1.1 Iron Oxide--Red
4.9 Tin Oxide
3.2 Yellow Ochre
1.9 Bentonite
Comments: Richard Busch Ceramics Monthly 2/2003
Author mixes this glaze 2/3 with 1/3 Busch white satin matte
By itself a warm tan breaking brown over iron bearing clay body.
Picture 1 - Left to right
A - Waxwing Brown from Mastering Cone 6 Glazes - note some blistering at the perimeter
B - C. Harris Temoku - (the version I have posted on cone6pots
C - Transparent grey-green scrap glaze of unknown composition
Picture 2 - Left to right
C - Transparent grey-green scrap glaze mentioned above
D - Rutile Matte
E - Cone 5-6 Clear rendered the Nutmeg a uniform translucent grey breaking brown
Picture 3 - Left to right
F - Floating red - rich caramel and chocolate
G - Storer Semi-matte green - blistered where thin
H - GA 25 Black - variation of Ron Roy's licorice? From M Bailey's Glazes Cone 6
Sharon Canfield
Me too, I really like the discoveries that come with using a vertical surface. Not many pottery pieces my husband produces are flat:)
Nadine Mercader said:
Feb 11, 2015
Joseph Fireborn
The D result is fantastic. Probably my favorite. I like the test cylinder. Nice work thanks for sharing.
Sep 6, 2015
Randy McCall
One of my favorite glazes layering to give great depth and movement. Over and under. Some of my best pieces have used that glaze. Experiment with it all the time.
Oct 27, 2015