Nils Lou

The Art of Firing

Designing, building and trouble shooting kilns

96 Pages, B&W and color images, size 7-1/2 x 10 inches
Review  by Jock Dempsey

So what is a review of a book about pottery kilns doing on a blacksmithing web-site? To those of us that design and build our own gas forges it is obvious. Many pottery kilns use the same fuel and are built of the same materials as many blacksmith forges. Most of the design problems are the same, but a few are different. For anyone interested in building either kilns or forges much of the information applies to both. This is a must read resource for anyone building or operating a pottery kiln or interested in high temperature furnaces. It is well written, clear and understandable. It was recommended to me by Feriz Delkic the founder of International Technical Ceramics.

This review is targeted toward metalworkers building gas or oil forges or small melting furnaces.
Page 19, Raising the roof of a stacked brick kiln. 
Click for Enlargement Page 19, Raising the roof of a stacked brick kiln.
Click images for enlargements.
First there is a matter of scale. Kilns are typically larger than blacksmith forges. But kilns ARE similar to industrial furnaces used to feed large forging machines up to and including having "car bottoms". Then there is the temperature range. Kilns generally run lower temperatures than a blacksmith's forge.

Kilns heat up gradually. Forges heat rapidly. In comparison a small blacksmith's forge will use the same BTU's as a much larger kiln.

The author covers many kiln designs and discusses the advantages and disadvantages of each. There are many photos and clear concise diagrams of the various kilns. A few are detailed but this book assumes you have some background in the use and construction of kilns. Specific materials are discussed including the economic advantages of using insulating bricks and ITC-100

The discussions on refractories and efficiency are very clear. Hard dense refractories absorb a lot of heat as well as conduct it out of the kiln. All this waste heat must be created by using more fuel. But there are also places where for mechanical reasons hard refractories are needed. This applies to both potters' kilns and blacksmiths' forges.

Page 51. Tom Orr and Tom Keacher unloading East Creek anagama - Click for Enlargement The discussed kiln designs include arch top and groundhog kilns. Up draught, down draught and the Minnesota Flat Top kiln, its derivations and others.

Modifying atmospheres in electric kilns by the injection of propane and the need to protect the heating elements with ceramic coatings is also covered.

Although this is a small book it covers a lot of ground.
Liquid LPG burner - Click for Enlargement
Page 51, Liquid LPG burner with internal evaporator.

Different fuel types are discussed including saw dust and propane. The burner design and operation are applicable to both kiln and forge. One problem common to blacksmith's forges is the need to draw LPG fuel at rates greater than the normal evaporation rates. Liquid fuel burners are discussed and references for in depth study are given.

Orifice vs Pressure and BTU chart. 
Click for Enlargement A much reproduced orifice vs. pressure and supplied BTU chart is included. This chart has been reproduced in many references and needs to be updated as well as verified. The original source is not given.

Pressure is given in inches of water column, orifice size in number drill sizes. Flow is given in cubic feet per hour.

Temporary Kiln built of 3/4" plywood and ITC-100 
Click for Enlargement There are several pages on refractory coatings and the benefits of products from International Technical Ceramics. ITC-100 HT is demonstrated as improving fuel efficiency by reflecting a high degree of infrared. Experiments are shown demonstrating that it also extends the life of kiln furniture.

ITC-100 and ITC-296A were used as coatings in a small electric kiln and increased its working temperature from cone 6 to cone 10. ITC-100 protected the heating elements but ITC-213 is recommended for metal parts. The ITC-296A is a high purity coating that has a higher reflectance than the ITC-100

To the right is a temporary kiln made of 3/4" (19mm) plywood! It is coated inside and on the heat exposed edges with ITC-100. This is a single firing (maybe twice) kiln useful for odd shape work or a process that might otherwise damage expensive kiln linings.

The author is an Associate Professor of Art at Linfield College in Oregon and has been a potter for 40 years. While teaching at Hamline University in St.Paul Minnesota he developed the design for the Minnesota Flat Top car kiln. Variations of this kiln have been built in more than 20 countries.

Published by:
A & C Black, London
and in the US by
Gentle Breeze
Oviedo, Florida

Price £14.99 UK - $24.95 US
ISBN 1-889-25011-2
Available from potter's suppliers.

Copyright © 2002 by Jock Dempsey, DEMPSEY'S FORGE
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