Milling of 1850-70
This is probably one of the most misunderstood of all milling process,
even more so, than the operation of a roller mill. The reason that the "American"
or "flat grinding process" was also called "low milling"
was that the upper runner stone was set low or close to the bottom bed stone
during milling. In "new process" milling the runner stone is set
"half as much higher" above the bed stone as compared to low milling.
Thus it was also known as "half-high milling." The roller milling
process was known as "high milling" or "gradual reduction"
milling because the runner stone would be set even higher.
In low milling the idea is to avoid producing as much middlings as possible
because as much flour was to be produced as possible in a single grind.
Middlings is a material that was considered a waste product along with the
bran. The second idea of low milling was to avoid regrinding material at
all costs. With the conventional milling setups, regrinding of all ready
ground material presented problems with feeding it into the millstones,
and created heat generated problems. So then with new process milling the
idea was to create as much middlings as possible because this is where the
bulk of the flour was produced from. The middlings are ground on separate
stones called "middling stones" or "middling pony,"
and the material is then bolted on separate reels. The flour produced from
this process was known as "patent flour" because it was produced
from a "patented" process. When the "patent flour" was
run in with the "bakers" or "clear flour" (the flour
made produced from the first grind of the wheat) the resulting mix or blend
was called "straight flour."
During the latter stage of the "new process" milling era smooth
germ iron rollers were introduced and they used tailings stock to increase
the yield. Many mills also began the process of regrinding the bran on a
pair of small millstones just to touch it, not cutting it and leaving it
as a broad flake. The bran stones were then gradually replaced by another
pair of smooth iron rollers but by that time the rollers had begun to replace
the millstone entirely.
Every miller wanted to produce "patent flour," and as much of
it as possible because it was advertised as being produced from a "patented"
process. Perhaps because of the psychological effect to get anything "patented"
it had to be applied for, and granted by the federal government. Because
of this "patent flour" commanded almost a double price that the
old "bakers" or "clear flour." The new spring wheat
over shadowed and took the lead above the best winter wheat made under the
old process of milling. The "new process" spring wheat mills were
mainly in the central plans of the United States and Canada, while the old
soft winter wheat mills were in the eastern part of the United States. By
the time many eastern mills begin to adopt the "new process" milling
soon after that the milling process changed once again. Some mills used
their original ending millstones as middling stones. Ending stones were
a smaller diameter pair of millstones that were originally used to preclean
wheat if they still remained in place. The mills that installed the smaller
middlings millstones some times installed them on an upper floor level than
the traditional millstones. One reason was that they were smaller and lighter,
and could be located more easily on an upper level. They were often belt
driven like the old smut machines and mounted on a waist high platform to
make them easier to dress. Another reason goes back to one of the original
concepts of Oliver Evans that was to stack the machinery above each other
on different levels. Some millers tried to regrind the middlings on the
same stone that ground it the first time. The second and third regrinds
meant that the stones could not be set higher and had to be set closer and
closer. This is where the heat generated problems occurred. Heat can burn
up the gluten in the flour and destroy the flour's ability to rise and make
good bread. Oliver Evans suggested mixing whole wheat kernels with the middlings
for regrinding but this only produced a "bastardized" patent flour
in some miller's opinion.
The problem with higher grinding of middlings from the first grind, it did
improve the flour made in the first grinding of the wheat, but there was
a limit to higher grinding of the middlings to improve the later grindings,
and less flour was made in the process. It was also impossible to make the
desired quantity and quantity of flour with the old style of millstone dress
with the large amount of grinding surfaces known as "land." This
was prevalent in the old style of flat grinding. With the old system the
miller wanted flour and not middlings so the millstones had a larger proportion
of "lands" than furrows. So then in "new process" milling
there is a higher percentage of furrows than lands. The lands were reduced
and the amount of furrows increased. The grain is dropped below the surface
of the land and when it is swept up a feather edge to the surface it is
actually sheered by two passing feather edges or passing lands.
It was also found that the capacity of feed practiced in the old system
had to be cut down and often the feed system of the damsel and shoe changed
completely. Instead of the traditional rap-rap of the song of the damsel
that filled the mill with its centuries old song, a silent feed system was
developed. The damsel rather than having flutes on the upper end, the once
fluted portion became an auger that drawled down the middlings from the
hopper or chop box down into the eye of the millstones. It became a force
The speed of the millstones was also reduced. In the old practice of milling,
the idea was to run the millstones close together, with as much feed and
speed as possible. Thus a lot of pressure was applied upon the grain and
it produced a lot of hot damp meal. With the new process of milling the
products were cool and slow grinding became the "order of the day."
Besides the differences in how the grain was milled in the old and new process,
the care of the millstones, gradually some of the milling machinery became
obsolete. It was the one machine that Oliver Evans was the most proudest
of that was the one that disappeared, the hopper-boy. Gradually it became
evident that the hopper-boy was no longer needed because the grindings and
the chop was now cooler. It was soon discovered that spreading it out the
ground material in the elevator cups in small amounts, and running in along
in chutes and conveyors was sufficient enough to cool it. Generally most
people don't understand why the hopper-boy fell out of favor. Many people
over the years have apologized to me that their mill does not have a hopper-boy
as if it was something that was lost or misplaced over the years. The hopper-boy
disappeared not because of its inherent problem with the possibility of
material falling into the flour and contaminating it. Millers did try and
enclose it the revolving rake in a round walled enclosure, but they discovered
that in doing that, it destroyed its cooling effect. The hopper-boy needed
to be out in the center of the room mixing with fresh air. The main reason
that the hopper-boy became no longer needed, was that the milling processes
and methods changed.
Millstone dressing also became more of a science than a one time art. The
lightest of dressing and cracking was now sufficient in new process milling.
Some millers claimed that millstones the French millstones without any dressing
would grind the grain sufficiently just by use of the porous openings. Improvements
in driving irons, balancing and truing the stones became more important.
Various styles of dress was worked out that could produce more middlings
that ever before. The miller spent his time, energy and resources to produce
middlings as large, round and clean as possible. This was done at a time
when there were no guidelines to follow, or text books written at the time
that were available the miller to learn from. This perhaps added to the
sense of mystery that some how the process by which it was produced was
"patented" through the federal government. It a government secret
between them and the miller. Basically the millers had to think for themselves.
Some times they would try one thing and if that did not work then they tried
another possibility. It became a perquisite that the miller now learned
to dress and care for the millstones himself. It larger merchant mills they
had crews of men who did nothing but dress millstones.
An important machine that came in to later use during this era was the middlings
purifier. The purifier separated the middlings with the use of air currents
thus separating the bran from the floury particles bonded to bran, known
as middlings. A mediocre grade of flour. View by some to be fit only for
the common or lower classes. The first middlings purifier was introduced
into America by Edmund N. LaCroix from France in 1871. It was first used
at the Washburn Mill in Minneapolis. New process mills that used smooth
germ rollers operated from 1875 to 1883. After that the new process milling
gradually went out of use because of the complete adoption of roller mills
to replace the millstones. Why did this not happen over night? One reason
was that the originally the Hungarian roller milling system that was brought
to America, it was not automatic. It was like a the system of flour milling
before Oliver Evans. Nothing was automatic, and each pair of rolls was a
separate machine. Material was introduced into each pair of rollers as if
it was being poured into a millstone hopper by hand. Then it was gathered
up and carried to the next step or process by hand. At first the mills installed
corrugated rolls to break the wheat and retained the millings stones, and
used smooth iron, porcelain or both on the second middlings and tailings.
Even French millstone material was made into rollers for use in new process
milling. Gradually the rollers displace the millstones and in this time
the roller system became automated fully.
Buhr Stone Mill: This is the type of mill that was displaced by
the roller mill. Generally it was not the Oliver Evans mill that was displaced
by the roller milling system but the buhr stone mill that used new process
milling. The size and capacity changed from the old flat grinding system
to that of the "new process." The drawing does not show grain
storage bins, flour chests, packers, or feed or offal bins. The machinery
represented shows machinery mainly involved in the milling system of the
buhr stone mill. This illustration is figure 13, page 25 of "Practical
Milling," by Prof. B. W. Dedrick, National Miller, Chicago, Illinois,
The one odd thing about Prof. B. W. Dedrick drawings is that he had the
silent feed systems on the wheat stones and a conventional feed on the middlings
stones. It should be the direct opposite the wheat stones should have the
conventional feed and the middling stones should have the silent feed. The
silent feed system is shown on the previous page. The following is a list
of the parts of the mill in the order of the milling process:
D. Dump bin.
1. Elevator one.
R.S. Receiving separator.
W.C. Wheat conveyor.
2. Short elevator.
M.S. Milling separator.
W.G. Wheat garner.
D.R. Dust room.
W.S. Wheat stones.
M.S. Middling stones.
M. Main shaft.
U. Upright or vertical shaft.
J. Lay shaft on mill's second floor.
S.K. Sink in front of the millstones.
M.C. Meal conveyor.
4. Flour elevator.
B1. Bolting chest.
5. Middlings elevator.
6. Purified middlings elevator.
M.B. Middlings bin.
M.S. Middlings stones.
7. Ground middlings elevator.
B2. Bolting chest.
8. Tailings from middlings reels elevator.
B3. Meal bolting chest.
9. Flour elevator.
V. Vertical spout is a suction spout used to ventilate the millstones.
L. Lever used to adjust the top runner stone.
r. Rod used to adjust the millstones.
L.S. Hand wheel or screw.
The wheat stones are 48 inches in diameter and the middlings stones are
36 inches in diameter. The wheat millstones still operate at about 125 revolutions
per minute but the middling millstones run about 200 revolutions per minute.
The bolters operate 25 to 30 revolutions per minute. The elevators operate
40 to 45 revolutions per minute. The conveyor operates about 60 revolutions
per minute. Such a mill is capable of turning out 80 to 100 barrels of flour
in 24 hours. One barrel of flour contains 196 pounds or 14 stone. In 100
pounds of wheat there is about 72 percent of its total is white flour. In
a larger mill, it was the custom to have one or two extra pairs of millstones
to use in place of the ones taken up for millstone dressing. Oliver Evans
reels were 18 to 20 feet long. New process milling the reels became shorter
and were 8 to 12 feet long. Towards the end of new process milling cockle
machines and bran dusters came into usage. Diagonal elevators as in 1 an
9 were used only to discharge material on the opposite side of the top floor
thus acting as both an elevator and conveyor. Vertical elevators were much
easier to layout and install in mills than the diagonal ones. Vertical elevators
have to be operating at the proper speed for material to be discharged at
the top, while diagonal elevators can be operating at any speed for material
to be always discharged. Vertical elevators if not operating at the correct
speed the material will fall down the "down" leg and in time clog
up the system.
other Interior Views of Mills Circa 1850-70
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Copyright 2001 by T.R. Hazen.