Glazes - for the Self-reliant Potter (GTZ, 1993, 179 p.) Appendix Glaze Recipes Color Pigments Ceramics Elements and Oxides Common Glaze Raw Materials Chemical Analysis of Glaze Materials Table of Standard Sives Table of Seger Cone Formulas Table of Seger Cones Table of Orton Cones Conversion Table for Pint Weights Density Dry content of a liquid Twaddell scale Properties of fuels Metric system Temperature conversion formula

Glazes - for the Self-reliant Potter (GTZ, 1993, 179 p.)

Appendix

Glaze Recipes

Glaze recipes are included in this book with a word of caution: Because of the wide variations in raw materials around the world, the same recipe will produce different results in different locations.

So please consider these recipes to be good starting points. They are not guaranteed to work without some modifications but will put you in the general area of success. Most of the glazes are not described as glossy, matt, opaque etc. Try them out and modify them according to what you have learned in this book.

With regard to frits these vary from one manufacturer to another. As frit making is not economical for the small potter, it is suggested to substitute locally available frits. The recipes are compiled from many different sources, which are listed below.

Fritted boron glazes for low temperatures

GLAZE #1.
Temperature: 980 °C

Frit recipe
Borax	15.5
Potash feldspar	34.8
Marble	17.9
Boric acid	31.8

Glaze recipe
Frit	35.7
Potash feldspar	25.8
Kaolin	1.0
Quartz	17.2
Soda feldspar	20.3

Glaze formula
0.25	K2O	0.40	Al2O3	3.50	SiO2
0.15	Na2O			1.00	B2O3
0.60	CaO

GLAZE #2.
Temperature: 980°C

Frit recipe
Borax	33.3
Potash feldspar	21.1
Marble	16.6
Kaolin	9.0
Quartz	20.0

Glaze recipe
Frit	35.1
Potash feldspar	24.3
Magnesium carbonate	4.3
Barium carbonate	8.2
Kaolin	11.9
Quartz	17.2

Glaze formula
0.17	K2O	0.47	Al2O3	3.42	SiO2
0.16	Na2O			0.83	B2O3
0.25	CaO
0.25	MgO
0.17	BaO

GLAZE #3.
Temperature: 1080°C

Glaze recipe
Frit from glaze #2	35.9
Potash feldspar	16.7
Kaolin	15.5
Quartz	14.4
Marble	12.0
Dolomite	5.5

Glaze formula
0.40	K2O	0.30	Al2O3	2.80	SiO2
0.50	CaO			0.60	B2O3
0. 10	MgO

GLAZE #4.
Temperature: 1100°C

Frit recipe
Borax	10.0
Potash feldspar	33.5
Marble	15.3
Kaolin	4.0
Quartz	12.8
Boric acid	24.4

Glaze recipe
Frit	94.0
Kaolin	6.0

Glaze formula
0.34	K2O	0.34	Al2O3	3.5	SiO2
0.66	CaO			1.0	B2O3

GLAZE #5.
Temperature: 1040 °C
Clear transparent glaze will craze on most bodies.

Frit recipe
Borax	47.50
Boric acid	10.50
Potash feldspar	10.50
Quartz	21.00
Kaolin	8.50
Zinc oxide	2.00

Glaze recipe
Frit	62.00
Local red clay	12.00
Kaolin	8.00
Quartz	8.00
Potash feldspar	5.00
Barium carbonate	5.00

Glaze formula
0.11	K2O	0.48	Al2O3	3.83	SiO2
0.53	Na2O
0.16	BaO			1.36	B2O3
0.10	MgO
0.10	ZnO

Calculation of this formula is based on chemical analysis of local glaze materials.

GLAZE #6.
Temperature: 1040 °C
Semiopaque glaze.

Frit recipe
Borax	43.70
Marble	2.40
Talc	0.60
Zinc oxide	0.30
Kaolin	0.60
Rice husk ash*	40.00
Quartz	7.00

* About 30 parts quartz can replace the rice husk ash.

Glaze recipe
Frit	37.7
Wollastonite	5.0
Kaolin	16.0
Potash feldspar	6.0
Quartz	7.8
Zinc oxide	7.5
Zircon	20.0

Glaze formula
0.04	K2O	0.37	Al2O3	4.37	SiO2
0.27	Na2O			0.16	ZrO2
0.39	ZnO			0.48	B2O3
0.30	CaO

Calculation of this formula is based on chemical analysis of the local glaze materials. The content of zirconium oxide in the zircon used in this recipe is only half of what is normal for standard quality zircon.

GLAZE#7.
Temperature: 1040°C
Opaque, silky matt glaze.

Frit recipe
Borax	40.5
Marble	2.2
Talc	0.6
Zinc oxide	0.2
Kaolin	5,5
Quartz	43.7
Bone ash calcined	7.3

Glaze recipe
Frit	57.0
Kaolin	9.0
Ball clay	8.0
Quartz	11.0
Marble	2.0
Zinc oxide	13.0

Glaze formula
0.05	MgO	0.26	Al2O3	2.90	SiO2
0.25	Na2O
0.53	ZnO			0,50	B2O3
0.17	CaO

Nonfritted borax glazes

GLAZE #8.
Temperature: 1040 -1080 °C

Glaze recipe
Borax	7.2
Black local clay	15.00
Glass cullet	48.00
Barium carbonate	15.00
Manganese dioxide	15.00

Black glossy glaze used for tiles and sewage pipes.

Glaze formula
0.25	Na2O	0.06	Al2O3	1.25	SiO2
0.17	BaO
0.16	CaO			0.09	B2O3
0.11	MgO
0.3 I	MnO

GLAZE #9.
Temperature: 1020 -1040 °C

Glaze recipe
Borax	50.00
Local red clay	5.00
Rice husk ash	30.00
Whiting	4.00
Yellow ochre	11.00

Transparent, glossy glaze.

Glaze formula
0.73	K2O	0.11	Al2O3	1.71	SiO2
0.17	CaO
0.10	MgO			134	B2O3

GLAZE #10.
Temperature 1050 -1100 °C

Glaze recipe
Borax	30.00
Potash feldspar	25.00
Quartz	15.00
Dolomite	20.00
Ball clay	10.00

Glaze formula
0.41	CaO	0.29	Al2O3	2.29	SiO2
0.41	MgO
0.17	K2O			0.91	B2O3

GLAZE #11.
Temperature: 1260°C

Glaze recipe
Potash feldspar	16.6
Kaolin	11.0
Quartz	23.7
Marble	15.0
Borax	22.2
Soda ash	11.5

Glaze formula
0.09	K2O	0.21	Al2O3	1.90	SiO2
0.48	Na2O
0.43	CaO			0.36	B2O3

Glazes for heavy clay products

GLAZE #12.
Temperature: 960 -980 °C

Glaze recipe
Sodium silicate	34.0
Glass cullet	11.0
Zircon	30.0
Quartz	10.0
Kaolin	5.0

GLAZE #13.
Temperature: 920 -960 °C

Glaze recipe
Glass cullet	70.0
Local red clay	15.0
Whiting	15.0

Opaque low-cost glaze.

Glaze formula
0.56	CaO	0.13	Al203	1.94	SiO2
0,32	Na2O
0.12	Mg

GLAZE #14.
Temperature: 1000 °C

Frit recipe
Red lead	30.00
Quartz	26.30
Potash feldspar	12.20
Whiting	7.00
Borax	10.50
Magnesium carbonate	7.00
Zinc oxide	7.00

Glaze recipe
Frit	92
Kaolin	8

Glaze formula
0.31	PbO	0.12	Al2O3	1.50	SiO2
0.17	CaO
0.20	MgO			0.13	B2O3
0.05	K2O
0.07	Na2O
0.20	ZnO

GLAZE #15.
Temperature: 1000 °C

Prit recipe
Red lead	17.80
Quartz	26.10
Potash feldspar	22.40
Whiting	10.30
Boric acid	16.40
Soda ash	3.00
Kaolin	4.00

Glaze recipe
Frit	92.0
Kaolin	8.0

Glaze formula
0.31	PbO	0.34	Al2O3	3.07	SiO2
0.41	CaO
0.16	K2O			0.53	B2O3
0.11	Na2O

GLAZE #16.
Temperature: 1050°C

Frit recipe
Quartz	20.00
Potash feldspar	25.00
Whiting	7.00
Borax	25.00
Magnesium carbonate	5.00
Zjnc oxide	8.00
Zircon	10.00

Glaze recipe
Frit	92.0
Kaolin	8.0

Glaze formula
0.21	CaO	0.22	Al2O3	2.11	SiO2
0.18	MgO			0.16	ZrO2
0.13	K2O			0.39	B2O3
0.19	Na2O
0.29	ZnO

GLAZE #17.
Temperature: 950-1050°C

Frit recipe
Quartz	28.30
Potash feldspar	40.80
Whiting	7.00
Borax	13.00
Soda ash	5.10
Titanium dioxide	5.60

Glaze recipe
Frit	94.0
Kaolin	6.0

Glaze formula
0.32	CaO	0.42	Al2O3	4.20	SiO2
0.32	K2O			0.31	TiO2
0.36	Na2O			0.34	B2O3

GLAZE #18.
Temperature: 1000 -1100 °C

Frit recipe
Red lead	30.56
Quartz	20.83
Whiting	18.05
Borax	25.00
Kaolin	5.56

Glaze recipe
Frit	94 0
Kaolin	6.0

Glaze formula
0.47	CaO	0.11	Al2O3	1.13	SiO2
0.35	PbO
0.17	Na2O			0.34	B2O3

GLAZE #19.
Temperature: 1050 -1130 °C

Prit recipe
Quartz	34.20
Whiting	5.90
Borax	30.10
Zinc oxide	1.20
Boric acid	4.00
Kaolin	11.00
Zircon	12.70
Barium carbonate	1.00

Glaze recipe
Frit	95.0
Kaolin	3.0
Bentonite	2.0

Glaze formula
0.03	BaO	0.34	Al2O3	4.78	SiO2
0.37	CaO			0.43	ZrO2
0.50	Na2O			1.19	B2O3
0.10	ZnO

Stoneware glazes

GLAZE #20.
Temperature: 1200 -1250 °C

Glaze recipe
Potash feldspar	72.0
Kaolin	7.0
Quartz	8.0
Whiting	13.0

Glaze formula
0.50	CaO	0.60	Al2O3	3.72	SiO2
0.50	K2O3

GLAZE #21.
Temperature: 1200 -1250 °C

Glaze recipe
Local feldspar	62.0
Kaolin	5.5
Quartz	10.0
Whiting	11.0
Zinc oxide	5.0
Zlrcon	6.5

Glaze rormula
0.274	K2O	0.485	Al2O3	3.147	SiO2
0.124	Na2O			0.084	ZrO2
0.286	CaO
0.216	ZnO

Calculation based on analysis of local materials.

GLAZE#22.
Temperature: 1200 -1250 °C

Glaze recipe
Local feldspar	53.0
Kaolin	2.0
Quartz	28.0
Whiting	17.0
Zircon	+ 10.0

Glaze formula
0.250	K2O	0.403	Al2O3	3.912	SiO2
0.113	Na2O
0.637	CaO

GLAZE #23.
Temperature: 1250°C

Glaze recipe
Feldspar	40
Quartz	30
Whiting	20
Kaolin	10

Glaze formula
0.74	CaO	0.41	Al2O3	3.71	SiO2
0.26	K2O

GLAZE#24.
Temperature: 1180-1200°C

Glaze recipe
Potash feldspar	46.5
Quartz	10.7
Barium carbonate	16.5
Colemanite	1.6
Zinc oxide	6.7

Glaze formula
0.24	BaO	0.24	Al2O3	1.97	SiO2
0.28	CaO
0.24	K2O	0.41	B2O3
0.24	ZnO

GLAZE#25.
Temperature: 1200°C

Glaze recipe
Feldspar	51. 1
Quartz	5.9
Kaolin	10.8
Whiting	18.6
Zinc oxide	8.7
Bentonite	4.9

Glaze formula
0.48	CaO	0.37	Al2O3	2.03	SiO2
0.17	K2O
0.05	Na2O
0.02	MgO
0.27	ZnO

GLAZE#26.
Temperature: 1200-1250°C

Glaze recipe
Dolomite	3.9
Kaolin	7.7
Nepheline syenite	53.8
Quartz	23.1
Whiting	11.5

Glaze formula
0.51	CaO	0.56	Al2O3	3.56	SiO2
0.08	MgO
0.10	K2O
0.31	Na2O

GLAZE#27.
Temperature: 1250°C

Glaze recipe
Granite	63.6
Dolomite	27.3
Kaolin	9.1

Glaze formula
0.41	CaO	0.31	Al2O3	1.99	SiO2
0.39	MgO
0.10	K2O
0.10	Na2O

GLAZE #28.
Temperature: 1200 °C

Glaze recipe
Wood ash	50
Kaolin	5
Dolomite	3
Whiting	10
Bentonite	2
Feldspar	20
Quartz	5
Nepheline syenite	5

Glaze formula
0.51	CaO	0.09	Al2O3	0.73	SiO2
0.22	MgO
0.15	K2O
0.12	Na2O

GLAZE #29.
Temperature: 1240-1300°C

Glaze recipe
Feldspar	40
Ash	40
Pike clay	20

Glaze formula
0.35	CaO	0.17	Al2O3	1.27	SiO2
0.25	MgO
0.27	K2O
0.13	Na2O

Calculation based on oak ash.

Sources of recipes
Many of the glaze recipes are taken from Ceramic Glazes, Stefanov/Batschwarov, Bauverlag
GmbH, Wiesbaden and Berlin, 1988, and the original sources are also mentioned.

Color Pigments

Below are listed some recipes for color pigments. In the chapter on color pigments you will find instructions on how to prepare them. These recipes will seldom work right away, but they can be used as starting points for developing color pigments based on local materials. As with all ceramic colors, the color depends very much on firing conditions, purity of the raw materials and composition of clay and glazes.

Cobalt Blue Pigments

	Sky blue	Light blue	Royal blue	Green- blue	Dark blue	Dark blue
Cobalt oxide	5	10	20	10	45	44.6
Alumina	90	60	60	10		55.4
Zinc oxide	5	30	20	80
Kaolin					55

Green Pigments

	Victoria green	Bluish green	Russian Green	Green Green	Olive Green	Olive
Chrome oxide	25.0	25.8	15.0	30	19.6	32
Cobalt oxide		35.5	10.0
Nickel oxide					8.7	16
Alumina		38.7
Whiting	50.0
Quartz	25.0		60.0	20	39.1	28
Feldspar			15.0	50
Calcined borax					32.6	24

Black Pigments

	Black	Black	Black	Dark brown	Greenish black	Brownish black
Chrome oxide	44	17	32.3		65.5	48.8
Cobalt oxide	22	20	20.6
Iron oxide	24	35	41.2	45.5	34.5	51.2
Manganese oxide	10	20	5.9	54.5
Nickel oxide		8

Pink/Yellow Pigments

	Pink pink	Dark yellow	Deep yellow	Yellow yellow	Titan	Naples
Antimony oxide			40			40
Chrome oxide	1	1.7
Iron oxide			8			(+5)
Tin oxide	45					20
Quartz	30	54.5
Whiting	24
Red lead		3.5	40			40
Zinc oxide		40.3			50
Soda ash			12
Kaolin				11.3
Feldspar				20.8
Rutile				67.9	50

Red/Brown Pigments

	Orange brown	Red- brown	Light red- brown	Yellow- brown	Chocolate red	Iron
Rutile	37.5
Iron oxide		22.8	17.8	13.7	27.3	50.0
Chrome oxide		21.7	16.9	13.1	18.2
Zinc oxide	16.7	55.5	53.9	55.6	50.0
Alumina			11.4	17.6		50.0
Kaolin	16.7				4.5
Tin oxide	29.1

Violet/Turquoise

	Deep violet	Dark violet	Blue violet	Turquoises blue	Turquoise
Manganese oxide	40	70	45
Cobalt oxide	7		10	27
Cobalt carbonate					2
Chrome oxide				18
Copper oxide					40
Alumina				55
Quartz	53		25
Tin oxide		15			75
Kaolin		25
Zinc oxide			20

Ceramics Elements and Oxides

The molecular weights are listed with one decimal point. For glaze formula calculations you can use round up figures, eg. for iron with MW 55.8 you round it up to 56.

Common Glaze Raw Materials

CF	=	conversion factor
MP	=	melting point, °C (degrees Celsius)
*	=	decomposing temperatur

NOTE: melting point and decomposing temperature are only relative indicators of how materials behave in glaze. Melting point are affected by combinations of materials! (See eutectics).

Table "Common Glaze Raw Material" 1

Table "Common Glaze Raw Material" 2

Table "Common Glaze Raw Material" 3

Chemical Analysis of Glaze Materials

Table "Chemical Analysis of Glaze Materials"

Table of Standard Sives

Mesh means the number of threads per linear cm or inch of sieve cloth. Openings indicate the distance in mm between two threads.

Table of Seger Cone Formulas

"Table of Seger Cone Formulas" 1

"Table of Seger Cone Formulas" 2

"Table of Seger Cone Formulas" 3

Table of Seger Cones

"Table of Seger Cones"

Table of Orton Cones

(United States, Ohio, The E. Orton Jr. Ceramic Foundation) Bending temperatures of large cones when heated at 150°/hour

°C	°F	Cone No.	°C	°F	Cone No.
600	1112	022	1120	2048	02
614	1137	021	1137	2079	01
635	1175	020	1154	2109	1
683	1261	019	1162	2124	2
717	1323	018	1168	2134	3
747	1377	017	1186	2167	4
792	1458	016	1196	2185	5
804	1479	015	1222	2232	6
838	1540	014	1240	2264	7
852	1566	013	1263	2305	8
884	1623	012	1280	2336	9
894	1641	011	1305	2381	10
894	1641	010	1315	2399	11
923	1693	09	1326	2419	12
955	1751	08	1346	2455	13
984	1803	07	1366	2491	14
999	1830	06	1431	2608	15
1046	1915	05	1473	2683	16
1060	1940	04	1485	1705	17
1101	2014	03	1506	2743	18

Note: The temperatures indicated in these cone tables may not be the same as when the cones bend in the individual potter's kiln. Cones are not used for measuring temperatures but for indicating the condition of clay and glazes.

Conversion Table for Pint Weights

oz/pt UK	oz/pt US	S.G.	°TW
22	18.3	1.10	20
22.8	19	1.14	28
23	19.2	1.15	30
24	20	1.20	40
25	20.8	1.25	50
25.2	21	1.26	52
26	21.7	1.30	60
26.4	22	1.32	64
27	22.5	1.35	70
27.6	23	1.38	76
28	23.3	1.40	80
28.8	24	1.44	88
29	24.2	1.45	90
30	25	1.50	100
31	25.8	1.55	110
31.2	26	1.56	112
32	26.7	1.60	120
32.4	27	1.62	124
33	27.5	1.65	130
33.6	28	1.68	136
34	28.3	1.70	140
34.8	29	1.74	148
35	29.2	1.75	150
36	30	1.80	160
37	30.8	1.85	170
37.2	31	1.86	171
38	31.6	1.89	179

Density

Specific gravity (SG) of a material, a mixture of materials or a clay slip is expressed as how many times it is heavier than the same amount of water, i.e. how many kg per 1 liter volume or gram per cm³. Density is the weight per volume unit and in the metric system this equals specific gravity (g/cc or kg/l) but in many countries slip densities are still measured in ounces per pint.

The density of a clay slip is found by weighing 1 liter of the slip. If it weighs 1.6 kg the slip has a density of 1.6.

Dry content of a liquid

Brogniart's Formula.

It is often useful to know the dry weight of materials in liquid clay slips or glazes. First find the weight of 1 liter of the liquid. The density (specific gravity, g/cm³) of the dry material has to be known. For clay materials it is close to 2.5 . Density of glazes has to be calculated from the density of the materials in the glaze recipe.

Dry weight in g = (W -1000) x D / D -1

W = weight in g of 1 liter liquid
D = density of dry material

Twaddell scale

Clay and glaze suspensions have normally densities between 1.0 and 2.0. On hydrometers used for measuring glaze and slip densities the densities between 1.0 and 2.0 have been divided into 200 units. These units are called degrees Twaddell and the formula for calculating these is:

°TW = (density -1) x 200

°TW Density = °TW/200 + 1

Properties of fuels

Average properties of solid fuels

		Wood	Peat	Lignite	Bituminous Coal	Charcoal
Moisture content as found	%	25 - 50	90	50	2
Moisture content at firing	%	10 - 15	15 - 20	15	2	2
Volatile matters	%	80	65	50	30	10
fixed carbon	%	20	30	45	65	89
ash	%	trace	5	5	5	1
Chemical analysis:
carbon, C	%	50.0	57.5	70.0	86.0	93.0
hydrogen, H	%	6.0	5.5	5.0	5.5	2.5
oxygen, O	%	43.0	35.0	23.00	6.0	3.0
nitrogen + sulphur		1.0	2.0	2.0	2.5	1.5
Calorific value:
cal/g
dry fuel	gross	4450	5000	6400	8600	8300
	net	4130	4710	6140	8310	8170
normal fuel	gross	3780	3800	5170	8000	8050
	net	3420	3460	4870	7720	7910

Properties of dry wood

		Specific gravity	Ash %	cal/g
Hardwood:	ash	.74	.6	4450
	beech	.68	.6	4500
	oak	.83	.4	4360
softwood:	fir	.45	.3	4770
	pine	.48	.4	4820
	elm	.56	.5	4470

Note:
Heat or calorific value is measured in calories per gram of fuel. One calorie is the heat required to heat 1 gram of water 1°C.

Gross clorific value is the heat that theoretically can be obtained, whereas net value is what is normally obtained when firing a kiln. Both values are included for comparison with other fuels.

Properties of liquid fuels

		Waste oil	Heavy fuel oil	Medium fuel oil	Light fuel oil	Kerosene
Specific gravity		0.9 - 1	1.1 - 0.94	0.93 - 0.91	0.9 - 0.81	0.78
flash point °C		250	200	150	105	55
viscosity		very high	high	medium	low	very low
calorific value:
cal/g	gross	10300	10055	10130	10300	11100
	net	9480	9536	9695

Metric system

"Metric system"

Temperature conversion formula

"Temperature conversion formula"

Conversion formulas:

X°C = X x 9/5 + 32 °F

Y°C = Y x 32/9 + 5 °C

Example: 573 °C = 1058° + 5.4° = 1063.4 °F

500 is found in the left column and the 70 is found at the top. The equivalent of 570 is the crossing point and then the final digit is added.