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Organising glaze formulas: John W Conrad details his organisational system for glazes.

[ILLUSTRATION OMITTED]

Over the years I collected more than 7000 ceramics formulas and compiled them on 'Keysort' cards - an early type of IBM punch card. The experience of having formulas given to me, finding formulas in books and magazines and making my own has led me to perceive a need for a uniform organising method. Comparing one formula to another was difficult due to the fact that ingredients were expressed in a variety of names, percentages, percent by weight and/ or batch weight. Several hundred formulas were collected and grew to such a large number of formulas that I developed a simplified standardised and organised system. The formula and its information were laid out using a consistent format and data outline based on 100 for the total amount of each formula. The Keysort card system works but it is tedious sorting the cards with sorting rods and by hand so this system is no longer used with the advent of the computer. The only thing that may be needed for this organisation is adding the unity formula to the data. Due to this type of organisation it is an option and may or may not be needed.

For the sake of clarification, ceramics terms 'formula' and 'recipe' are interchangeable. I use formula. The start of this organisational method was used in my first ceramic book Ceramic Formulas: The Complete Compendium, Macmillan, 1972. As far as I can determine, this was the first English text on a ceramics formula collection with related information on ceramics formulas ever internationally published.

The computer and glaze calculation programs empower one to use this organisational method as quite viable and manageable. Using a computer, notebook, index cards and/or just plain notes for storage of formulas needs a standard layout. To help illustrate this, in general it is understood that a base glaze is clear or white and devoid of colour. The glue, electrolyte and colour making metallics are taken out of the formulas and listed as additives. There are always exceptions with the major ones being saturated metallics. This is because the high amount of metallics in glazes affects the transparency, surface, glaze flow, colour, fluxing and markings, thus it is kept as part of the glaze.

During the collecting of ceramics formulas it was found that many formulas were identical or almost identical with only the title, organisation, how the amounts are listed, or name of mineral being different. In the sidebar is an illustration of three glaze formulas for a cone 9-10 glaze, with little glaze flow, transparent, pale greenish and fired in both oxidation and reduction.

At first glance the formulas appear different, but all three are the same. Various potash felspars are available and in this formula comparing one to another the difference is insignificant. Many minerals have more than one name as example the following four group examples being the same: [silica, quart, and flint]; {whiting and calcium carbonate]; [lithium felspar and Spodumene]; and [china clay, EPK, and kaolin]. One example the metallic colorant (copper carbonate) is part of the base formula, in the other two the metallic is outside. This can be confusing but a standard organization will clarify the potential confusion.

To further explain the complexity of using and collecting ceramic formulas the following illustration show four glazes ranging from as little as one ingredient, then two, then three, and fourthly 13 ingredients.

The following chart shows the major ceramic formula categories and the subdivisions Ceramic Formulas for Clay, Engobe, Stain and Glaze Subdivision Categories as Part of Master Outline Organizing Ceramic Formulas.
Clay Formulas

Hand Building Throwing General Usage Sculpture
Slip casting Special

Engobe Formulas

Listed by fired colour and or usage

Stain Formulas

White Black Brown Yellow
Orange Red Purple Blue
Green Special Effects

Glaze Formulas

Ash Artificial Red Aventurine Barium/
Black (Tenmoku) Boron Bristol strontium
China Paints Chrome red Chung Celadon
Crackle Crater Crystalline Copper red
Lustre Egyptian Paste Matte Cullet
Lead Magnesia Enamel/over- Dolomite matte
Mid-Temp. Overglaze glaze Frit
Salt/soda Saturated Majolica Fuming lustre
Stoneware Metallics Porcelain Matte
Unusual (special Terra Sigillata Shino Raku
effects Tenmoku Underglaze Single-fire


After years of developing, the following glaze example is the recommended way to organise ceramics formulas with the imperative data. The clay, engobe and stain formulas are organised in the same way, using a base of 100.

Now when a new glaze is acquired and calculated to be a base of 100 and the ingredients are listed from highest to lowest one can find out easily if it duplicates any glaze in the collection. The formula title, source, date, firing temperature, finished result details and particulars are listed with the formula completing the data.
Glaze G#44 (A) Blue- Conrad's collection, 8/8/08 (C)
 Black (B)

Felspar, Custer 41 (D) Temperature = C/3-5 Ox or Rd (F)
Cornwall stone 25 (E) Surface = High gloss (G)
Gerstley borate 25 Transparency = Translucent (H)
Edgar Plastic 04 Fluidity = Little flow (I)
Kaolin
Zinc oxide 03 Colour = Clear (J)
Lithium 02 Toxicity = Avoid breathing dust (K)
carbonate
 100(M) Application techniques =
 Brush 3 thin coats (L)
Glue (CMC) (N) Notes: (O) Unity formula (P)
GG#44 [above] 100 (Q)
Copper oxide 04 (R) Surface = High gloss (G)
Cobalt oxide 02 Transparency = Opaque (H)
Granular Fluidity = Little flow (I)
magnetite Colour = Blue-black (J)
trace Glaze appl. = Brush 3 thin coats (L)
 Notes = Subtle black specks (O)


A. Type of formula--Clay, engobe, glaze, stain or other and code, formula, or source number.

B. Title, most formulas have an identification title (optional).

C. Source (magazine, book, ceramist, made-up and so forth) date found and/or used.

D. Ingredients are listed percent by weight from greatest first then down to the least. Unless a special glaze such as saturated metal, all glazes are listed as a base glaze with the colorant taken out and listed after the base glaze. Colourants are listed

The computer and glaze calculation programs empower one to use this organisational method as quite viable and manageable. Using a computer, notebook, index cards and/or just plain notes for storage of formulas needs a standard layout. To help illustrate this, in general it is understood that a base glaze is clear or white and devoid of colour. outside the base glaze, the resulting colour and other attributes are listed next to it.

E. Items of the same weight are alphabetically listed.

F. Temperature or temperature range, atmosphere condition (oxidation, neutral, reduction), soak time.

G. Surface (high gloss, gloss, semi-gloss, waxy, semi-matt, satin matt, matt, emery paper, stony, crater and so forth).

H. Transparent, semi-transparent, translucent, milky, opaque.

I. Extent of glaze flow - no flow, little, some flow, fluid, extremely fluid.

J. Colour, crystals if any, marbling, unusual features.

K. Toxicity if any.

L. Any special application methods used --brush, sponge, spray, splatter and so forth.

M. Total weight of base glaze based on 100 (99.9 to 100.1).

N. Items not part of the base glaze (glue, water, granular metallics, non-ceramic and so forth).

O. Additional information about the glaze.

P. Unity formulas an option to include or not.

Q. The glaze (base) in which the additives will be added.

R. Colourants and additional supplements are listed by weight heaviest to lightest.

This glaze standard formula layout and organisation can be used for clay, engobe, stain or other ceramics formulas. Having a vast collection of ceramics formulas necessitates their subdivision as listed. I have more than 100 formulas just for the Black Pearl glaze and to keep from duplicating, they are listed in their own category under black glazes. In the subdivision for glazes, only a few glazes are available for chrome red, artificial red, aventurine, cullet and enamel due to being unusual or seldom used. On the other hand, numerous formulas are available for ash, earthenware, porcelain, Raku and stoneware glazes. This is a start in standardising and organising ceramics formulas.

For the sake of clarification, ceramics terms 'formula' and 'recipe' are interchangeable. I use formula. The start of this organisational method was used in my first ceramic book Ceramic Formulas: The Complete Compendium, Macmillan, 1972.

John Conrad is an author, educator and ceramics artist who lives and works in California, US.
Formula #1

Potash felspar 48
Spodumene 05
Whiting 14
Kaolin 14
Silica 19
 100
Copper carbonate 02
CMC added

Formula #2

Custer felspar 177.6
Flint 703
Calcium carbonate 51.8
Lithium felspar 18.5
Edgar Plastic kaolin 51.8
 373.0
Copper carbonate 07.4
CMC added

Formula #3

Spodumene 04.7
Lime 14.0
China clay 14.0
Quartz 18.7
Potash felspar 46.7
Copper carbonate 01.9
 100.0
CMC added

Glaze I Glaze 2

Albany slip 100 Barnard clay 95
 Cobalt oxide .05
 100

Glaze 3 Glaze 4

Ohio slip 90 Felspar, Custer 29.93
Gerstley borate 9 Whiting 20.00
Granular iron 1 Kaolin 09.95
 100 Flint 09.32
 Alumina hydrate 06.95
 Zinc oxide 06.64
 Zircopax 05.40
 Gerstley borate 04.29
 Rutile 02.27
 Dolomite 02.09
 Yellow ochre 02.09
 Bentonite 02.04
 100.00
 CMC
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Author:Conrad, John W.
Publication:Ceramics Technical
Date:Nov 1, 2012
Words:1514
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