Dremel 876 Specifications download pdf (Page 9)

Shelf cones enable you to get to know the personality of

your kiln. Yes, they do have one, believe it or not. A good

cook knows that their oven performs with different character-

istics, as does your kiln. As the kiln fires, there may be areas

of the kiln significantly cooler or hotter, affecting the outcome

of your fired pieces. It is highly recommended that shelf

cones be used with every firing and at various placements on

shelves to develop a graphic picture to the heating peculiarities

of your kiln. Keeping a record of firing times, cone placement

and degree of deformation can alleviate many heartaches

down the road. These records will help you make adjustments

to the firing process. A half cone difference throughout the

kiln chamber is considered very good.

Cone Numbering System Relative to

Temperatures

Cone manufacturers produce firing cones for every

conceivable heat treatment involving maturing clays and

glazes. The chart that follows lists the cones and the temper-

ature where, under specified conditions, they would bend.

The numbering system may appear confusing, but it is

similar to a thermometer. Increasing numbers above an

imaginary zero cone represent higher temperatures, while

increasingly minus numbers below zero represents lower

temperatures. Minus numbers (and lower temperatures) are

indicated by "0" preceding the number. For example, Cone

06 is lower (cooler) than Cone 05. The zero is very

important when reading and following firing directions for

the materials used.

Shelf cones numbered the same as the small cones used

in the sitter are designed to deform and mature at a given

degree of heat. They are not interchangeable in use for the

shelf or sitter. The smaller cones can not be used as a shelf

cone because they require a hotter temperature to deform.

Smaller cones would give inaccurate indication of the kiln

firing. Concurrently, a large shelf cone forced into the sitter

would damage the mechanism.

Kiln Sitter

The W.P. Dawson Kiln Sitter is the control for the kiln and

is the most widely used one today. There are newer types of

kilns with computer controls that will be discussed later. We

highly recommend installing a sitter on you kiln for it enables

you to have more consistent firings with less chance of

misfirings.

Place a small cone in the cone supports and the sensing

rod, as illustrated in View A. Try to center the cone in the

sitter, for it can make a few degrees difference in the firing.

The sitter is activated at the beginning of firing manually,

outside of the kiln (View B), and turned off by the deformation

of the small pyrometric cone on the inside of the kiln (View C).

Do not jar the kiln sitter and tube assembly during loading or

firing; it could result in overfiring or misfiring of the kiln.

Make sure to keep your kiln sitter clean. The cone

supports and porcelain tube assembly should be vacuumed

before the first firing and periodically with use. If a piece

explodes during firing, thoroughly clean and vacuum the tube

assembly and the whole kiln (walls, floor and elements) before

the next firing.

Guide

Cone

Firing

Cone

Guard

Cone

Firing

Guide

Cone

Correct Deformation After Firing

Firing

Cone

Guard

Cone

Cone Numbering System

Cone # 108˚ F

* 270˚F

Kiln Color Ware Type

10 2345 2381 White Commercial

9 2300 2336 Porcelain

8 2257 2305

7 2219 2264

6 2194 2232 Hobby Porcelain

5 2151 2185 & Stoneware

4 2134 2167

3 2106 2134

2 2088 2124 High Fire Glaze

1 2077 2109 Semi-Vitreous

01 2043 2079 Ware

02 2014 2048 Yellow

03 1987 2014

04 1922 1940 Earthenware

05 1888 1915

06 1816 1830 Low Fire Glazes

07 1783 1803

08 1733 1751 Orange

09 1679 1693

010 1629 1641

011 1627 1641

012 1591 1623

013 1586 1566 Cherry Red

014 1533 1540 Semi-Melting Glass

015 1454 1479 (Bottle Sagging)

016 1407 1458

017 1341 1377 Decals

018 1285 1323 Metallics,

019 1234 1261 China Paint & Lusters

020 1157 1175 Dull Red

021 1116 1137 Glass Colors

022 1085 1112 Glass Decals

* If rate of heat increase is 108ºF per hour.

If rate of heat increase is 270ºF per hour.

Color of objects in kiln at this temperature.

Follow manufacturer’s directions when choosing correct cone number.

These photos are from W.P. Dawson, Inc. Kiln Sitter Operating Manual.

If you did not receive a manual with your kiln, we recommend you obtain

one from the manufacturer.

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Dremel 876 Specifications Page 9

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