History of Jeffery-Dewitt Co. and Dr. Jeffery

[Trade Journal]

Publication: Michigan Manufacturer and Financial Record

Detroit, MI, United States
vol. 18, no. 1, p. 6, col. 1-3

Have Established Porcelain Industry in Detroit


The Jeffery Dewitt Company, of Detroit, enters the manufacturing field with a new porcelain high potential insulator which will keeps its insulating value under the strain to which it is subjected on high tension transmission lines.

The design and construction of this insulator are important elements in its efficiency, but it derives its great superiority from the high grade of porcelain of which it is made.

High grade porcelain is the Jeffery Dewitt Company's specialty and in the production of this article it is a leader in this country. It produces a grade of porcelain in every respect superior to that which the American consumer imported almost entirely from Germany until the great war taught him that he could find it at home. The American user of porcelain imported largely because of precedent and prejudice. Today, per force of necessity, he has forgotten prejudices and precedents, and the Jeffery Dewitt Company has been greatly instrumental in making him forget.


This illustration has not been processed yet.


The company, at its inception some eight years ago, was devoted to the manufacture of spark plugs alone. As the auto motor was improved and speeded up, the durability and insulating quality of the spark plug porcelain had to be correspondingly improved to keep pace with the higher voltage and more intense heat to which it was subjected. Research and experimentation along this line by Dr. Jeffery led to the production of a spark plug porcelain of such acknowledged superiority that the Jeffery Dewitt porcelains were soon in demand by other spark plug producers. This condition of things induced the Jeffery Dewitt Company to give itself over to the manufacture of porcelain only. Consequently it sold its spark plug business some two years ago to the Champion Spark Plug Company, of Toledo, its largest competitor. It now furnishes the Champion Company from twelve to fifteen million spark plug porcelains per annum.

About this time it became necessary to increase the producing capacity of the Jeffery Dewitt plant 100 per cent. At the present writing buildings and equipment are being added which will again double that capacity. This cause of the superior quality of its porcelain. One of the new buildings now being erected is to be devoted entirely to the new high potential insulator. Five new modern kilns are being added to the three already in operation, each with a capacity of from 300,000 to 350,000 pieces every firing, and each costing $2,500. When the improvements now under way have been completed the Jeffery Dewitt Company will have the most up-to-date porcelain manufacturing plant in the country. This kind of a plant is to be distinguished from a pottery. The distinction between pottery and porcelain lies in the manipulation of the clays and the high temperature to which the latter product is submitted in firing. One of the new branches of porcelain manufacture which the Jeffery Dewitt Company has taken up is the making of plumbers' supplies of all kinds and it is at present catering to the needs of every concern of note in this line In the United States. Something of the meaning of this statement may be gathered from the information that one firm in Detroit alone is being supplied with three and one-half million gas-cock handles a year. A day's mail brings orders for pieces by the hundred thousand.

The latest departure which the Jeffery Dewitt Company has made from its original line of production has been to begin the manufacture of laboratory ware. This is started within the year.

Now this company produces 85 per cent of all the spark plug porcelains used in the United States, it turns out 60 per cent of all the plumbers' supplies; and when it comes to laboratory ware, the Jeffery Dewitt Company claims to be in a class by itself, producing a grade of porcelain superior in quality to the Royal Berlin and Royal Messine, the two famous German laboratory wares which it was previously thought could never be equalled. This superiority has been proven by tests and these tests prove the quality of our American clays as well as of our American skill and ingenuity. It is worthy of note that only two or three other concerns in the United States are producing high grade porcelain for laboratory use and none of these has arrived at the standard of our Michigan production. The an order for 60,000 evaporating dishes, its original order in this ware, because it was not then satisfied with its ability to fill the order satisfactorily. What was lost by that order has been more than regained through the standard of ware since established. Now one day's orders will call for ten or twenty thousand dishes varying in size from one and one-half inches in diameter to twelve inches.

It has taken years of experimenting and enormous expenditures to arrive at this stage of perfection. The same body of clay is used in all three branches of the porcelain manufacture. This body is made from thirty to forty mixtures of different clays and spars from as many different sources. Our continent abounds in sources of this material and the supply is unlimited.

The raw material is freed from its grit in great tumblers by means of Belgian pebbles. It is mixed with water until it will run and is put through a series of sieves. After this the water is pressed out of it and the clay itself pressed into slabs. It is then stored for thirty days to season.

For the smaller parts, as spark plugs, cook handles, etc., the clay is first made into round plugs from which these small parts are turned or formed; for the larger pieces, plaster parts moulds and forming tools are used.

The glaze is applied to the smaller pieces by machinery and done very rapidly; the larger ones are dipped. For firing in the kilns the pieces are placed in Baggers. These are circular pots made for a fire clay.

The decorating of the pieces is a process of the company's own and the rapidity with which rows of girls apply names, trade marks or other decorations to these small pieces is remarkable. A good deal of the work on the small articles is done by girls. The work is clean and light and the girls really seem to enjoy their tasks. Indeed, an air of contentment, harmony and co-operation is in evidence throughout the Jeffery Dewitt plant.

The faring of the kilns, maintaining a proper and uniform temperature, is a scientific task and a very important one, too. The loss of a firing kiln's contents may mean as much as $5,000. Shrinkage is another element which contributes to the task involved and it has to be figured to .005 of an inch entailing rigid inspections of the finished product.

There is considerable dust from the turning of the dry clay plugs. This dust is taken care of by a system of the company's design and the dust is utilized. The hot air blower for the dry kiln, though built by the American Blower Company, is after Dr. Jeffery's design the dry kiln itself is a feature of the plant; it is rather unique, there is no other like it. The institution has its own analytical laboratory in charge of Prof. E. T. Montgomery, formerly of Alfred University, Alfred, N. Y., an authority on ceramics.

The Jeffery Dewitt Company is composed of Dr. J. A. Jeffery, president; D. A. Jeffery, vice-president; M. C. Dewitt, secretary-treasurer; W. G. Helfer, sales manager; A. McLeod, managed high potential Insulator department. The company came to Detroit from Newark, New Jersey, in 1910 to get into the center of the automobile industry. Its present plant covers three acres at Butler Avenue and the Grand Trunk Railway.


Keywords:Jeffery-Dewitt Insulator Company : Jeffery-Dewitt Company : Joseph A. Jeffery
Researcher notes: 
Supplemental information: 
Researcher:Elton Gish
Date completed:December 26, 2013 by: Elton Gish;