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Stockton Fire Brick Company
In 1920, the old Stockton Fire and Enamel Brick Company was
reorganized and renamed the Stockton Fire
Brick Company. Charles M. Jackson was president of the new company and John T. Roberts was secretary and
manager. The plant was built by the former company in 1907. It was located on the west side of the
Southern Pacific railroad near California and 9th streets in south Stockton. The company office was
first in the Rialto Building at 116 North Montgomery Street in San Francisco from 1921 to 1927, and
afterwards in the Russ Building at 235 Montgomery Street in San Francisco. In 1924, a single-story
office building was built at the brickyard. John T. Roberts (shown on the right) became the president
and manager in 1925 and remained so until the company was purchased by Gladding, McBean and Company in 1943.
The company owned or leased the clay properties from which it mined the clays. The main source of clay
came from their Edwin clay mine at Jones Butte near Ione in Amador County. Ione sand was obtained from
the pit of the Ione Fire Brick Company, and Lincoln fire clay was mined by a subsidiary company, the
Clay Corporation of California. Quartz for grog was mainly from Placer County, and diatomaceous shale
used in their insulating brick was purchased from mines in Santa Barbara County. All raw material was
delivered to the Stockton plant by rail.
View of the plant of the Stockton Fire Brick Company. From Dietrich, 1928.
The material was first put into the dry-pan grinder, screened, and then run through the pug mill. The
firebrick was made from a mixture of grog and fire clay, shaped in an auger machine and a pressing machine.
The high-grade checker brick (interlocking brick) was made from a mixture of grog and calcined clay, shaped
on an end-cut auger machine. The runner-brick (special shaped brick) was made of a similar mixture, formed
on an auger machine, and then sent to a specially designed machine for making joints and cutting the
side-holes. The insulating brick was made of a mixture of diatomaceous shale and clay and hand molded.
These bricks except the runner-brick were dried in waste-heat tunnel driers. The runner-brick, which
required uniform drying on all sides during the shrinkage period, were dried in a Carrier ejector
humidity drier, which was operated on a 13- to 15-hour schedule, beginning with a three-hour period at
145 degrees F and 40 percent humidity, and finished at 240 to 250 degrees F with a steadily declining
humidity. The bricks were set on drier cars parallel with the direction of the air current in the drier
so that the bricks would dry internally and externally at the same rate. Each car held 380 stacked bricks.
The drying period was 30 hours.
The fire clay products were fired in 12 oil-fired, round, down-draft kilns, which ranged in size from
12 feet to 32 feet in diameter. The kiln capacity ranged from 20,000 bricks (80 tons) to 100,000 bricks
(400 tons) each. The usual firing cycle was seven to eight days of firing to a temperature of 1,370 degrees C
(up to cone 11). The cooling period was of equal length. The insulating brick was fired in four 12-foot by
23-foot rectangular kilns. All of the kilns were equipped with base-metal thermocouples with automatic
recorders for accurate control of the firing cycle. There was a testing laboratory equipped with electrical
and optical pyrometers for measuring high temperatures and a conductometer for measuring the insulating
qualities of materials at high temperatures. The plant employed an average of 110 workers.
Excellent firebricks were made at this plant and they were in great demand by steel mills, iron foundries,
and shipyards from Alaska to South America and as far away as Japan and the Philippines. The firebricks
were made in standard 9-inch lengths and in many special shapes. The "CARNEGIE" brick was the best grade
of standard brick for resisting high temperatures under adverse load and spalling conditions. It was made of
quartz grog and calcined fire clay, formed in sanded molds, and repressed. Manager Roberts and other former
employees of the deceased Carnegie Brick and Pottery Company continued to make the CARNEGIE firebrick, which
was a well known brand in the local market. The brand "GASCO XX" was made of fire clay and quartz grog,
shaped in an auger machine, and single pressed. Both the "GASCO R" and "STOCKTON" were made of fire clay
and quartz grog, formed in an auger machine, and repressed. The "DIATEX" was their diatomaceous insulating
brick. The distinguishing features of the firebricks from this plant include the buff to salmon colored
clay body, with medium to coarse grains, and the brand name set inside a rounded rectangular plate.
Some of the places where the Stockton firebricks were used include the Mare Island Navy Yard in Vallejo,
the Bremmerton Navy Yard near Seattle, the Pacific Coast Steel Company in South San Francisco, and the Hercules
Powder Works at Hercules. E.H. Horner was the plant superintendent, succeeded by E.M. Marshall in 1930. In 1930,
the company built a second plant in Pittsburg to meet growing demands for firebrick. The Stockton plant
closed in 1932.
Stockton Fire Brick Company Bricks
Stockton Wire-Cut Firebrick
The wire-cut firebrick is gray with smooth surfaces. White subangular quartz grog up to 1/4 inch
across and blotchy brown iron spots 1/4 inch across, each constitutes 5 percent of the clay body. The
edges and corners were originally sharp, but often chipped or broken. The sides display transverse
grooves, minor crackles, orange flashing, and stack indentations. The faces show curved wire-cut grooves.
The marked face contains a raised round-rectangular name plate measuring 6 1/4 inches in length and 1 inch
in width. The name "STOCKTON" is recessed in block letters. It spans 5 1/8 inches in length and is 3/4 inch
high. This brick was made by the stiff-mud process with an extruding and wire-cut machine and then
repressed. Length 9 1/8, width 4 1/2, height 2 1/2.
View of the face of a STOCKTON wire-cut firebrick. The round-rectangular name plate is raised
and it contains the recessed brand name.
Stockton Pressed Firebrick
Stockton firebricks are white, gray, or yellow in color with smooth surfaces. Most surfaces display
tiny pits, crackles, and medium to coarse grains. In the bricks that contain quartz grog, subangular
white quartz up to 1/4 inch across constitutes up to 5% of the clay body. Similar amounts of brown,
blotchy or round iron spots up to 1/4 inch across, some with blister holes, can be seen on the surface.
The internal clay body crumbles or spalls easily making the brick quite fragile.
The sides may display orange flash patterns and stack indentations. The edges and corners were originally
sharp, but often chipped or broken. The unmarked face may show longitudinal grooves. The marked face
shows a variety of styles. One type, which is believed to be an early version, has a round-rectangular
name plate recessed in the center of the face. The plate measures 6 inches in length and 7/8 inches wide.
At each end of the plate are round holes 1/4 inch across. Between the holes is recessed the name "STOCKTON"
in block letters. The name spans 5 1/4 inches in length and is 3/4 inch high. A larger version of this
brick has a name plate 7 3/4 inches in length and 1 inch wide and set between the two holes the name spans
6 1/8 inches and is 3/4 inch high. Another type is with the
round-rectangular name plate without the two end holes, but one is slightly recessed and the other is
slightly raised. In the recessed plate, which is 6 1/4 inches long and 1 inch wide, the brand name
"STOCKTON" spans 5 1/4 inches, or in a widely spaced version 5 3/4 inches, in length and is 3/4 inch high.
In the raised plate, which is 6 inches long and 7/8 inch wide, the brand name is recessed with closely
spaced letters. The name spans 5 1/8 inches and is 3/4 inch high. There are likely other sizes
in these firebricks. These bricks were made by the soft-mud process and repressed or dry-pressed.
Length 8 7/8 - 9, width 4 3/8 - 4 1/2, height 2 1/2.
View of the face of a STOCKTON dry-pressed firebrick with the recessed brand name set between two holes that spans 5 1/4 inches.
View of the face of a STOCKTON dry-pressed firebrick with the recessed brand name set between two holes that spans 6 1/8 inches.
View of the face of a STOCKTON dry-pressed firebrick with a slightly raised round-rectangular name plate. Note the screws marks on the "S" and "N".
View of the face of a STOCKTON dry-pressed firebrick with a slightly recessed round-rectangular name plate. Recessed name spans a wider 5 3/4 inches.
View of the face of a STOCKTON dry-pressed firebrick with a slightly recessed round-rectangular name plate. Recessed name spans a tighter 5 1/4 inches.
Stockton Pressed Arch-shaped Firebrick
The Stockton arch-shaped firebrick is pressed, with yellow crackled surfures. It has a medium grained clay body with
5 percent round brown iron spots up to 1/4 inch across. The edges and corners are sharp, but often chipped or broken.
Stack indentations may be seen on the face. The marked face shows a recessed number "2 1/8", indicating the thinner
dimension of the arch. This is set inside a slightly raised circle plate 2 1/2 inches in diameter. Length 8 7/8,
width 4 1/2, height 2 1/2 - 2 1/8.
View of the marked face of a Stockton arch brick displaying "2 1/8" for the thinner side of the brick. Donated by Stuart Guedon.
View of the end of a Stockton arch brick. The left side is 2 1/2 inches long and the right side is 2 1/8 in long.
GASCO Wire-Cut Firebrick
GASCO brand firebricks, started by the Stockton Fire and Enamel Brick Company and continued here, were wire-cut and repressed in three different
styles. A buff GASCO firebrick had 10 percent subangular white quartz grog up to 1/4 inch across and one percent round
brown iron spots up to 1/4 inch across. The face displays curved wire-cut grooves. The sides display transverse grooves
and crackles. The brand name "GASCO" on the face spans 4 1/2 inches and 3/4 inch high and is recessed in block letters.
This brick measures 8 3/4 inches in length, 4 1/2 inches in width, and 2 1/2 inches in height. There were two styles of the
GASCO XX firebrick. The one with the smaller size "XX" is a yellow wire-cut with 5 percent subangular white quartz up
to 1/4 inch across and 2 percent round brown iron spots and blister holes up to 1/4 inch across. The face displays
curved wire-cut grooves. The sides are crackled and some may show stack indentations. The brand name "GASCO XX" on the
face spans 4 1/4 inches and 3/4 inch high in recessed block letters. The "XX" beneath the brand name spans 1 3/4 inches
and 5/8 high, also recessed. This brick measures 9 inches in length, 4 1/2 inches in width, and 2 1/2 inches in height.
In the larger size "XX", the brand name spans 3 1/8 inches and 5/8 inch high in recessed block letters. Note that the
letters are set closer in this brick than the previously mentioned brick. Beneath the brand name the larger "XX" spans
2 inches and 1 inch high. This brick measures slightly smaller in width at 9 inches in length, 4 3/8 inches in width,
and 2 1/2 inches in height.
View of the marked face of a GASCO firebrick.
View of the marked face of a GASCO XX firebrick. The double X is 5/8 inch high.
View of the marked face of a GASCO XX firebrick. The double X is 1 inch high and with closer set letters in the brand name.
DIABLO Pressed Firebrick
A DIABLO dry pressed firebrick, started by the Stockton Fire and Enamel Brick Company and continued here, is buff with
smooth, pitted surfaces. The clay body is medium grained with 2 percent round
brown iron spots up to 1/8 inch across. The bottom face has longitudinal striations. The marked face has the brand
name "DIABLO" in recessed block letters that span 5 5/8 inches and is 3/4 inch high. The example shown has the face
mostly destroyed or covered by mortar so that only the "D" and "B" are shown. This brick measures 9 inches in length,
4 1/2 inches in width, and 2 1/2 inches in height.
View of the marked face of a DIABLO firebrick. Donated by Petter L. Rosenquist.
CARNEGIE Pressed Firebrick
View of the marked face of a CARNEGIE pressed key no. 1 firebrick. Photo courtesy of Steve Curtiss.
View of the marked face of a CARNEGIE pressed no. 2 firebrick. Photo courtesy of Steve Curtiss.
The CARNEGIE pressed oversized block, started by the Stockton Fire and Enamel Brick Company and continued here,
is buff with smooth surfaces that is crackled. It contains 20 percent subangular white quartz grog. The brand name
"CARNEGIE" is recessed in thin block letters that spans 4 7/8 inches in length and is 3/4 inch high. The logo is
an "S" 3/4 inch in height inside a slightly raised circle that is 1 1/8 inches in diameter. This block measures
9 1/8 inches in length, 6 3/4 inches in width, and 2 1/2 inches in height.
View of the marked face of a CARNEGIE pressed oversized block displaying the "S" logo.
Brick and Clay Record, July 30, 1907, p. 37.
Copyright © 2009 Dan Mosier
Brick and Clay Record, v. 57, no 4, 1920, p. 328.
Brick and Clay Record, v. 64, no 7, 1924, p. 518.
Brick and Clay Record, v. 77, no 8, 1930, p. 412.
Dietrich, Waldemar F. The Clay Resources and the Ceramic Industry of
California. California State Mining Bureau Bulletin 99, 1928, p. 209-212.
Laizure, C.M., 1925, San Joaquin County. California State Mining Bureau 21st Report of the State
Mineralogist, p. 188-189.
San Francisco City Directories, 1920-1935.
Stockton City Directories, 1907-1935.
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