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## glaze course lesson two part one july 2 2000

### hal mc whinnie on sun 2 jul 00

note; HERE IS THE FIRST PART OF THE SECOND LESSON, PART TWO WILL BE SENT
LATER THIS WEEK.

IF YOU WOULD LIKE TO SEND ME COPIES OF YOUR HOMEWORK, PLEASE MAIL TO ME OFF
LIST.
HALCHAOS5@EMAIL.MSN.COM.

ONLINE GLAZE COURSE
LESSON TWO PART ONE
The seger method

The Seger method of glaze calculation provides a mathematical model for the
conceptualization of a ceramic glaze formula. The model provides for a
three-part analysis and the glaze components are grouped according to the
amount of oxygen present in the chemical formula for each one.

Ro r2o3 ro2
Feldspars aluminas the silicas
Flint
Feldspar china clays glass cullett

Ball clays
The borons
Refractors
Frits

The elements in the ro column must not exceed 1.00 molecular equilvents. The
elements in r2o3 and ro2 are related to each other by a proportion that we
shall employ which is called the alumina/silica ratio

A seger formula for a gloss glaze for cone 6
Knao0.20 al2o3 sio2
Cao0.40 0.25 2.50
Mgo 0.10
Lio o.010
tio 0.10
Cuo 0.05
Feo 0.05
1.0 molecular equilvents

The above formula is for a cone 6 blue green gloss glaze, which is opaque.
When calculated using a computer based software the following is the formula
for the above glaze

First step
Analysis of seger by weight
Sio2 62.83
Al2o3 10.66
Tio 3.34
Cao 9.37
Mgo 1.69
Feo 3.01
Lio 1.25
K20 7.86

Step two
Convert to recipe by percent of weight
Lithium carb 3.12
Silica 18.45
Tin 3.15
Whiting 15.17
Iron 3.07
Custer spar 57.04

Step three
Convert to recipe in percent or grams or proportions
Flint 18.45
Iron oxide 3.07
Lithium carb 3.12
Custer spar 57.04
Tin oxide 3.15
Whiting 15.17
Copper 3%

A computer program by zakin was used to create the above glaze recipe which
can be read as grams based on 100 percent or by percent in a proportional
analysis

If glazes in this category contain reasonably strong melters they will be
vitreous. Their high silica content encourages durability and transparency.
Their normal alumna content discourages glaze flow even if strong melters
are present. This is an excellent category for transparent glazes

HOMEWORK

1] WRITE A Seger formula for a clear gloss glaze for cone 10
2 write a Seger formula for a blue Matt glazes for cone 5.