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The Art of the Millstones, How They Work

The Art of the Millstones, How They Work
Theodore R. Hazen

The Movement of the Millstones (Starting and stopping a pair of millstone)

The miller would open a sack of grain and pour it into the millstone hopper, or the grain would already be stored above the millstones in a bin on the floor above. The miller would simply reach over and open a gate that would fill the hopper with about 50 to 100 pounds depending upon the type of grain.

Now the miller was ready to start the mill. Then he must open the control gate on the mill's sluice box. There are several schools of thought about starting and stopping a mill. One is that the millstones should be together, the miller opens the control gate and the water begins filling the upper buckets of the water wheel. As the water fills the first bucket it over spills into the second and then third and so on. When the water is over flowing the water wheel the miller will slowly begin to raise the runner millstone. The water wheel would begin to turn as well as the gears and the millstones. The machinery in the mill would come alive and very quickly the mill will begin to turn at a fast speed. All the time the grain has been slowly fed into the millstones and the miller now lowers the runner stone closer to the stationary bed stone, and the material coming out from the millstones grows finer and finer. Then gradually the miller adjust the millstones for the desired grind.

The other method is the opposite, before turning on the water onto the wheel, the miller raises the top runner millstone as far as its adjustment will allow it to rise. Then the miller goes and gradually begins to open the control gate, and the water then begins to slowly fill the first bucket on top of the water wheel. When the water has filled the buckets so that the top of the water wheel is heavier than the rest of the wheel, the water wheel will begin to turn. As the water wheel begins to turn and gain in speed the miller then begins to slowly lower the upper runner stone downward and the material begins coming out of the millstones becomes finer. Then the miller adjust the millstones for the desired grind that he wants.

One method is about as good as long as it is not hard the machinery. There is also several different ways you can stop the mill. One method of stopping the mill is just to close the control gate, and when the water stops flowing the mill will stop. A variation on this method of stopping the mill is to close the control gate and when the machinery begins to slow down you gradually raise the runner millstone. When the weight of the water wheel equalizes or when the water empties from all of the buckets the machinery will stop. Both methods will work for gear and belt driven pairs of millstones. The problem is the lag time it takes once you close the control gate to when the machinery actually stops. This can be a very long time of part of the mill's machinery is broken or jammed, or especially if someone is caught in the turning parts of the mill.

Another method of stopping the millstones is to push an extra handful of grain into the millstones. The millstones with the added amount of grain will act like a car that has sudden gotten too much gasoline, it will be begin to stall. When this happens you gradually bring the two millstones together with the added cushion of grain between the millstones. The added weight of each millstone together should over take the weight of water and the mill suddenly stops as if you applied the breaks. This is a good method is something breaks or someone or something gets caught in the machinery. In a mill where the millstones are belt driven the drive belt turning the millstones may suddenly jump off or snap so this method works better with gear driven millstones. The problem is with the old style of wooden mill gearing is when the gear teeth are worn too much they may suddenly snap like match sticks but if someone is caught in the machinery you take that risk. A new problem or danger may arise when you have forgotten that the water wheel still contains kinetic energy or water enough to make the wheel turn wildly until it empties. What then may happen is if you forget about the water in the wheel and begin raising the runner millstone to clean between them after a days work using the millstone crane. The millstone will whip off the millstone spindle wildly when raised by the millstone crane. It will quickly screw itself off of the millstone spindle and stop once it has cleared the spindle. The millstone still may come loose from the bails and pins dropping through the floor going downward into the mill's basement.

Many a miller may still use this method of starting and stopping the mill by gradually bringing the millstones together because he never has to close the control gate just raise and lower the runner millstone, and to then adjust the grind. Water will then fall over the stopped will and create an interesting effect for people passing by the mill. Some people passing by the mill may then be drawing into the mill by unusual effect of water cascading over the wheel.

The Action of the Millstones (A pair of millstones for producing fine flour)

Most people do not know the exact process at work underneath the millstone cover. All they may see is the millstone hopper which is an open upside down pyramid sitting on top of the millstone cover full of grain. Some millstone hoppers have a control gate to regulate the flow or the volume of grain moving out of the millstone hopper through the bottom approximate 4 by 4 inch hole or opening. If the millstone hopper has a gate to control the flow, it may just be a small wooden paddle, a single arm mounted in several straps also made of wood. The gate slides up or downward. Usually once it is adjusted the miller never has to touch it unless he wants to change the rate of the grinding or change the type of grain he is grinding on the same millstone.

The grain then falls into a device hung below the hopper with leather straps called a shoe. It is called a shoe because originally it looked like a wooden shoe but slowly over the years its design has changed. The shoe can be raised or lower at one end to allow more or less grain to fall into the millstones. To ensure that it is always a constant rate the shoe is vibrated back and forth a turning damsel. The damsel is mounted on the top of the balance rynd in pockets in the center hole of the upper turning millstone. The top end of the damsel is turning in a hole in the wooden horse frame that holds the shoe and millstone hopper. Some damsels are adjustable up or down a metal shaft so they can be used on different millstones. Some damsels are metal shafts with wooden blocks or strips screwed to the shaft while others are made of wood with large round wire staples placed around the shaft to create raised or fluted ridges. Some millers may have different damsels for different rates of feed. One damsel may have only 4 flutes while another may have 6 to a dozen fluted edges around the shaft.

Drawing "Millstone" by T.R. Hazen, 1984.

The damsel got it same back in the days of Chaucer's Canterbury Tales when some make chauvinist miller referred to the rapping sound the shoe made against the turning shaft as like a damsel singing her song. The mill was never silent as long as she would be singing her song. The damsel would be constantly singing her song and make the make work.

The ensure that the shoe always makes contact with the damsel some mills have a wooden spring or "miller willow," attached to the side of the horse frame on the side opposite of the long arm that wraps around one side of the damsel. A millers willow is a wooden spring made out of ash wood and a string is attached around a notch in the end of the spring to the end of the shoe, usually through the same hole that the crook string is looped.

The grain falls into the eye of the runner stone, and the flow of grain is controlled by the arrangement of the shoe and the damsel rather than by the size of the hole or "eye" of the stone. With the turning runner the balance rynd and below that the driver spread the grain evenly between the two stones as it falls and hits these two turning bars. The gap between the two stones is regulated by the miller to adjust the fineness of the flour. These working surfaces of the millstones is hidden from view when the mill is operating to create a down draft that cause the ground material to be carried down a chute. Most people only see the grain going in and where the flour comes out a chute, and what is in between it remains a mystery.

A bed stone and its runner stone

Around the edges of the millstones and to the inside of the millstone cover normally lays 20 to 25 pounds of ground material and the excess falls down the chute. Traditionally the miller would only lift the millstone cover to clean between the millstones. At that time it was usually tossed out or used for animal feed. A dishonest miller might lift the millstone cover after each batch of grain he ground taking that amount as an excess toll. Sometimes the millstone cover was much larger than the size of the millstones so the miller could take more or possibly instead of being round it had multiple corners to trap an excess amount. This was called the "miller's mite" the stuff that fell though the cracks or was trapped in the system belonged to the miller.

In ancient mills the millstones turned in a round trough with a chute on one side but as time passed mills began to have more power so the millstones gradually became more covered to keep down the dust. The millers though that they needed small paddles of sweeps attached to the rim of the turning stone to keep the ground material at all times going down the chute. The added weight of these small paddles effected the balance of the millstone or got caught against the inside cover. Then in time the millers discovered they were not needed. Because air is drawn into the stones with the grain to keep them cool at long as the cover is over the millstones there is a down draft that is created that carries the grain down the chute beyond the amount that lays around the millstones.

A drawing from one of the HABS-HAER sheets

Most people have never been in a mill when it is operating let alone know what happens between the two millstones. Often people refer to the millstones as rocks and as far as they know the rocks mash up the grain up into flour. Many years ago the people who advocated using the modern roller milled flour began an old wives tale that says, "You don't want to eat stone ground flour because you might bite down on a piece of rock from the millstone." That is just not the case you don't get any stone particles in the flour normally when the mill is grinding because the millstones never touch. A pair of millstones need to be redressed every three or four week and in that time a pair of millstones can grind two to three hundred thousand pounds of grain.

There is a rare case that one may find stone chips in the flour but it does not come from the grinding action of the millstones but from the neglect of the miller or millstone dresser. After a pair of millstones have been dressed, no matter how well they have been swept or vacuumed they still contain small particles of stone. They need to be purged of the stone chips so that when you grind for the public the product is stone free of these chips. The amount of grain that you need to grind between the millstones to purge them after dressing is about one sack of grain (50 to 75 pounds). The miller may use an old sack of old grain that he would have tossed out normally. Once the grain is run through the millstones it should always be thrown out. The miller also uses this grain to see if the millstones have also been dressed properly. Sometimes he may have to take them apart again and do some more dressing.

The reason that the millstones should never touch are for the following reasons: (1) The stone of the millstone would be reduced into the flour or meal. (2) The millstones would wear out very quickly. (3) If the millstone actually touch they may stop or (4) most importantly they would create a shower of sparks. The dust from wheat, rye, barley and oats is more explosive than gunpowder and 35 time more explosive than coal dust. Corn and buckwheat do not contain explosive dust because corn is a different cereal grain and buckwheat is an herb. Buckwheat and rye produce the most dust of them all in the process of grinding. (5) Finally if they touch they would tend to stop.

Technically the millstones will do some grinding of the grain without anything on the grinding surface. Some say that porous opening in the French millstones are enough to create the grinding action between two millstones without dress. And then, of course, the rest is left up to the art of the miller how he maintains his mill and the millstones. The miller may or may not be forth coming with information about what happens between the millstones. Some millers will only goes as far as the grain gets ground up between the two rocks. This response that it is stone ground, may be your only answer in some cases. The good miller who knows that the millstones should have sharp surfaces furrows to provide more efficient grinding of the grain.

Furrows and Lands (The grinding surface of the millstones)

A pair of millstones lies hidden from view in a wooden case called a vat. The millstones work together in pairs with a revolving upper turning millstone called the "runner" stone, and the fixed stationary bottom stone called the "bed" stone. Many people have lived their whole lives taking sacks or turns of grain to the local mill to have it ground into flour or meal and have never seen the millstones apart to see their surface or the process of maintaining the grooves which is called "dressing."

A discarded millstone outside and removed from the mill may or not be laying on its back to reveal patterns of furrows and lands on the grinding surface. So that is this pattern of the "grinding beams" beams used for in the milling process some may ask.

Are they used for cutting the grain into flour and meal? Or are they used as "furrows" in the farmers field to move the farmers plow across the "land," but in this case it moves the grain across the land of the millstones. They could be "air-furrows" for the movement of air between the two millstones to keep the grain from over heating? Then they could be "pairs of furrows" used to transport the grain between each pair of crossing furrows create a cutting against each other like scissors.

A pair of French millstones

If you remove the runner millstone off the the millstone spindle and flip it over to look at both millstones. You will discover that the pattern on both millstones is identical. When you place the runner stone back onto the spindle and rotate it, the furrow pattern from the bottom to the upper turning millstone is reversed. This is where the scissor cutting action occurs. Even though the mill may be stopped all you need to do is look the pattern on the millstone surface and way the furrows are laid out with the back to the leading edges you can tell of the upper runner millstone revolves to the left or to the right, clockwise or counter clockwise. It does make a difference when you install millstones in a mill. A pair of millstones that are dress backwards to which the basement gears and water wheel turn will have a very difficult time in grinding grain. Even some of the most expensive mill restorations (that have won all sorts of restoration awards), years later someone may discovered that the millstones that they installed years before were dressed backwards to the direction that the gears rotate and the water wheel turns. Millstones that turn with the sun turn clockwise and millstones that turn against the sun turn counter clockwise.

Most tide mills operated only with the outgoing tides because of the layout in the pattern of the millstone dress being clockwise or counter clockwise. The Popular Grove Tide Mill in Mathews County, Virginia, operated with the incoming and out going tides. The water wheel shaft had two master gears that faced each other, and in between is a wallower gear that could be moved and engage either one of the two gears when the mill is stopped between tides. Above this was a large pulley that operated the millstones by a leather belt. This ensured that the millstones always turned in the proper direction. The late Charlie Howell developed a dress pattern for a similar tide mill in England. The dress pattern had furrows that one end began and the other edge of the stone and ended next to it around the circumference of the millstone. As the furrow move inward towards the eye it looped over itself and thus the leading edge changed direction to that it was at the other side. The whole millstone surface was covered with these pie shaped loops. The furrows sort of look like a narrow wishbone with long legs and a narrow loop at the top where they come close together around the eye. Charlie was satisfied that it did what he intended it to do, but I understand in England they are still arguing out that point writher or not it actually did was it was designed to do or not.

Cutaway Drawing of Millstones in Use.
This cutaway shows the grinding action of two millstones with a right hand dress.

The furrows are used to cut the grain like a pair of scissors, as well as move the grain outward from the center of the millstones to the outer circumference and they are used to increase the air space between the millstone to keep the grind cooler. The condition of the pattern makes up for the "sharpness" of the millstones and for the fineness of the flour. A "dull" pair of millstones will not properly grind and separate the brain from the inner kernel and take more power to operate. A dull pair of millstones will not scrape off the bran in a large flake but with tare it into small particles which is then difficult to sift out from the flour. So a sharp pair of millstones will scrape off the bran in a nice large flake and then continue to reduce the inside endosperm into smaller particles.

The furrows do not radiate outwards from the center of the stone like many would think. Rather they are more or less set at a tangent to the eye of the stone. They are arranged in groups known as harps or quarters, each group consists of a "master furrow" which runs from the eye of the stone to the outer edge. The master furrow is the primary furrow on the surface of the millstone. There is a variable number of secondary furrows, perhaps three or four or five furrows. The first secondary furrow is called the "journeyman furrow," this is the second largest furrow in a quarter of a millstone with quarter dress pattern, parallel and immediately adjacent to the master furrow on one side and the next furrow or apprentice furrow on the other side. The "apprentice furrow" the third largest furrow in a quarter of a millstone with a quarter dress pattern, parallel and immediately adjacent to the journeyman furrow on one side and the butterfly furrow on the other side. "The "butterfly furrow," the smallest of the four millstone furrows in one quarter of a millstone in quarter dress. Sometimes this furrow is also called the fly furrow. If the millstone has a fifth furrow it may or may not have a name depending upon if the miller or millstone dresser gives it a pet name or not.

What happens when the grain falls into the eye of the millstones, it is moved outward between the two millstones by the turning motion of the upper runner millstone. The one method to discover what happens when the stone is grinding is to take the millstones apart after they have been doing some grinding of grain. As you look between the two millstones across the bottom millstone surface you will discover that the grain is in different phases of being reduced into flour or meal.

So beginning at the center or eye of the millstones where the grain is introduced between the two millstones you would find whole kernels of grain. A kernel of grain encounters large deep furrows that move it outward between the millstones. In this beginning process each kernel of grain would encounter 10 pairs of master furrows crossing each other and thus chopping the grain into small or broken bits of grain. In other works it makes cracked grains in the center of the millstones. If this were a roller milling process this would be the first break roller step.

At the grain spirals outward it will encounter a the second pair of additional furrows called the journeyman furrows and the grain will then become cut 20 times in this phase or like a second break roller step. The one difference beside twice as many furrows in this point of the millstone surface is that depth of the furrows is shallower than they it was at the millstone eye because the particle size is also getting smaller.

A standard text book (apprears to be English) illustration of a millstone.
The caption reads, "Common dress for a 4 ft. diameter millstone."

The old time millers who spoke about how many "quarters" a millstone had and how may furrows were in a quarter, it was also customary to speak about the millstone surface into three divisions. In the center was the "eye" or "bosom," in the middle is the "waist," and at the outer it is known as the "skirt." The bosom and waist is kept down more or less hidden below and behind the skirt so they cannot be seen.

The furrows at the leading edge of the eye are usually from one quarter to three quarters of an inch in depth, and this depth gradually is tapered off to come up to the surface of the stone at the skirt. The width of the furrows of a millstone are usually between one inch and one and a quarter inches in width.

Scissors cutting action of a pair of millstones as seen from the end view of two furrows.

The grinding surface of the millstones are divided between "furrows" and the "land." The furrows are grooves or channels cut out or into the face of the millstone. The furrows are deeper at the eye and become shallower as they move towards the skirt. Looking at a furrow from the side it has two separate edges. The "back edge" or bottom of the furrow is a sharp incline plane downward from the surface of the land. It culminates in what is known as a "front edge" or "feather edge." The feather edge tapers upward to meet the land, and it is the cutting edge of the furrow. The parts of a furrow are the back edge, heel, the bottom, and the feather edge. The lands are the portion of the face of the millstone left between the furrows and are in reality the true grinding surface of the millstones. This is because the grain is moved below the surface and when it returns it meets two surfaces or lands and it is sheared at this point by a constriction. The furrows purpose is then for distribution, ventilation and cutting because the grain is cut near where the feather edge meets the land.

Scissors action of a pair of millstones.

As the upper millstone moves across the surface of the lower millstone the large kernels of grain are trapped in side of the two back edges but as the millstone rotates a the grain is carried up the slop or incline where it meets the land or surface of the millstone. The sharp leading edges of the lands, passing over corresponding edges in the other stone, act rather like the blades in a pair of scissors, shearing or cutting the grains into fragments. The crossing feather edges constrict the grain within a smaller space and a shearing action occurs. If you take apart a pair of scissors a single blade is the same basic shape as a single furrow.

If the furrows did not answer their purpose of distribution, ventilation and cutting or breaking and there was no furrows on the millstone surface then the grain might be crushed. The problem with crushing the grain or applying too much pressure upon the grain as it is being ground is it that the oil is released from the germ in to the flour and will quickly cause it to turn rancid. As the grain is passed through the millstones it passes outward in two and one half revolutions. So as it is cut into four or five pieces and would continue to discharge it in a normal manor when every thing is fine and correct. But if it is tends to move outwards and be crowed and clog, then the draft is too severe. If it discharges too quickly with out being properly being ground, then the draft is too shallow. If the crowding occurred in the eye or the bosom of the stone then the grain will tend to lift the runner stone over coming the weight and pressure of the millstones and create great friction resistance, building up heat and moisture in the passing of the grain through the stone. The angle of the furrows is such that as they sweep across each other the grain and flour is forced outwards towards the edge of the stones. A rare type of millstone dress occurs when the furrow reached the outer last 6 to 8 to 10 inches of the millstone it will suddenly change direction and thus give the material a rapid movement outward which tends to distribute and discharge the material after reaching this point. This type of millstone dress is found in the 1764 Stillwater Mill in middle of the village of Stillwater, New Jersey.

When the millstones are normally grinding the weight of the turning upper millstone is transferred to the grinding action. So none of the weight of the stone is upon the bottom millstone spindle bearing. This is one reason that the millstone never should run empty it that the weight of the upper turning stone would quickly destroy that bearing.

When the material reaches this portion of the millstone the last 6 to 8 to 10 inches of the millstone they become vary close together. If you take a pair of millstones apart and lay a straight edge across the eye of the stone from one skirt to another. The millstones are not flat but each stone has a slight dishing to the surface. This is so as the grain moves outward in its two and one half revolutions the the particle size becomes smaller and the millstones become closer together. So as they reach the outer edge they may be only a paper thickness apart This area is called "the flouring of the stone" is the outer section of the grinding surface of the millstones where they come close together and the actual grain is turned into flour. Here the cracking lines are located and the are more furrows reducing the grain into flour. The flouring of the stone is like the reduction rollers and the cracking is like the germ rollers in a roller system.

The flat surfaces of the lands, which are roughened with small parallel grooves called stitching or cracking, they also pass across each other, grinding the fragments into still finer flour. In the process of dressing a millstone it is done in several steps. Facing is done to the surface painted on the lands, dressing is done to the furrows and cracking is done to the lands. The process is called "cracking" which means the laying in of "cracks" and leaving a space between the cracks. A cracking lines is just made with the sharp point or cutting edge of the mill bill. So if you looked at them closely from the side they would be V-shaped. The cracks extend across the land of the flouring of the stones and are varied in fineness as the occasion requires. A skillful stone dresser could put in 10 to 12 or perhaps 20 to 35, or even 50 cracks per inch with a full width of the pick or bill. The cracks are a series of parallel lines land across the land between the furrows. Some millers or millstone dressers see the need for cracking in a millstone while other say that it makes no difference. Usually millstones used for corn have no cracking and it is only found on millstones used to grind wheat and producing white flour.

Making it all come together (The art of the miller)

One problem with being a miller is that many millwrights would not share their information or knowledge among others. If they had one or two apprentices, one would be taught one thing and the other something totally different. So in this way they would not be able to connect their information for years. Millwrights were considered such powerful people or creatures that it was thought for a long time that their spit could kill a toad.

Second problem is that most millwrights know how to plan, layout, build, construct and maintain a mill, but they may not know the first thing about operating it or grinding grains. The millwrights would not have the "miller's touch," which is an important part of the art of the miller. The miller's touch is broken down into several methods. The fist method: You catch a handful of ground grain as it is coming out of the millstones in your open palm. Close you hand and make a fist and then open it. The ground material should somewhat cling together. If it falls apart through your hands like sand it is too dry and has too little moisture. It holds together like clay then it may have too much moisture. Then you use the palm method: were you hold the ground material in one palm and gently rub the other fore finger back and forth to judge the fineness of the ground material and determine the size and shape of the bran. The bran should be in large broad flakes, and not torn and reduced into small particles. Then you use the finger method: Were you use the thumb and index finger in a rotating curricular motion to judge the size of the particles for the right grind and if it will sift properly. These methods are done usually in very low light areas of the mill. Another thing that only a miller could teach another miller is now to temper and condition the wheat before you would grind it. Tempering and conditioning the wheat means to toughening the bran and mellowing the floury part of the wheat berry. To do this you place the wheat in a large bin and dampen it with water. You turn it over from time to time in a 24 hour period.

The miller could use his miller's touch even in the mill's dark basement where there was very little light. The miller knew when the millstones generated the smell of burning stone that they were too close together with too little grain between them. He also know when the millstones were out of balance because he knew when there began to bang together on one side of their rotation. This would also generate a bit of burning millstone smell when the stone hit. It would damage the furrows as well as creating sparks. As the miller used his senses to operate the mill. He knew what was happening between the millstones without being able to see between them, and he needed to be near them. The miller operated the millstones like a machine in a machine shop. The "speed" was how fast the water wheel was turning. The more water you add the more you could grind or more machinery you could run. The "feed" is the feed of the grind into the millstones, and the "cut" is the distance between the two millstones that determines how coarse or fine it grinds. The miller determines the feed and the speed of his grind for how much he wants to grind in a set time period, but this is compounded by the amount of moisture or lack of moisture in the grain. The average diameter pair of millstones could grind through a modern paper 50 pound sack of grain in 10 minutes but the miller may not want to do that. For one reason he may run low on available water by the end of the day. In today's world of mills being restored and open to the public, he may want to grind that 50 pound sack in an hour so as many visitors can possibly see the mill operating. Then people go away believing as they once did that they "could eat it as fast as it can get ground." Hopefully the good at least the miller knows different.

A pair of millstones 46 inches in diameter can grind 300 pounds of grain in an hour. A pair of millstones 48 inches in diameter can grind 400 pounds in an hour and a pair of millstones 56 inches in diameter can grind 500 pounds in an hour. The millstones would rotate at 120 to 125 revolutions per minute and require 4.5 to 10 horse power depending upon the condition of the millstone dress and if it was in need of dressing or not (if they were sharp or dull). The larger the diameter the slower the millstones would rotate and the smaller the millstones the faster the millstone would rotate such as middlings stones. Some where around 85 revolutions per minute would be the cut off that a millstone still could grind grain however in French mills their millstones revolved at 60 revolutions per minute.

The miller would have knowledge about operating the mill and making sure you keep your noise to the grind stone. If you keep your noise in the direction of the mill that means your ears are also in that direction. You run and operate the mill buy sight and sounds. Pay attention to your work, even if you are dealing with customers, the sounds of the mill are always in the back of your mind. One little sound out of place can mean a gear tooth coming out of place. The sudden picking up of the speed of the millstones means that your hoppers are getting low. If the hoppers run out the millstones will not have grain between them. The turning millstones so close together without grain between them they loose their natural heat dissipation and heat would be built up on the grind surface. They can over heat and crack or burst apart. A cracked millstone will burn the flour. Burnt flour wont make good bread, and the gluten is destroyed and won't rise. Millstones are better because the stones want to keep themselves cool the heat generated on the two grinding surfaces works it way to the cooler surfaces of the stone and is lost to the air. When the stones run out of grain they can over heat and crack and the gears over speed and the mill gets away from you and the gears tear themselves apart.

When the millstones are grinding grain a natural distribution of heat occurs within the stone itself. The heat is drawn towards the cooler surfaces of the stone, like water that wants to equalize itself, heat also wants to equalize it self throughout the stone. But when it is drawn to the outer edge it is lost or dissipated into the air. The problem with a crack in a millstone it that the millstone does not know it is two outer edge together and the millstone will keep drawing its heat towards what it thinks is an outer edge and the heat will continue to build up until you end up with burnt flour. A crack is much different than the seams in the blocks of buhrs in a French millstone they are cemented together to become a single stone.

Another thing a miller has to watch out for is "tramp iron." Tramp iron is metal pick up and mixed in with the grain before it gets to the mill. Tramp iron can be coins, nails, staples, screws, anything picked up from the fields or in storage and handling. If metal gets between the stones, it may cause the upper runner stone to jump off the spindle. A millstone weighing a ton or two can do a lot of damage before it comes to rest. A millstone turning 125 revolutions per minute will destroy the millstone cover and I seen then destroy machinery in a mill and go through a 14 inch square log wall like butter and before they come to rest out side the mill. Some small pieces of metal will go through the stones and come out like a shooting star out the chute. They can damage the dress and surface of the millstone. These can ignite the flour dust. Because a larger piece can make the millstone jump the spindle what is why after while they used large horse shoe magnets placed in chutes to catch the metal before it might get into the millstones.

Third problem is that most millwrights are not millstone dressers. Many millers learned how to do it out of necessity but may not have a good knowledge how it should be done correctly. The bad thing is they pass on bad knowledge and skills to others. Some say it does not matter what you do on a millstone that any marks or grooves will do something. The something will determine how the grain is ground and the bran is removed from the kernel. What the millwright would be most concerned about in a mills are several things the least being the process of grinding which was the miller's job.

If we look at ancient millstones we still find some form of dress or furrow. They also have some form of draft to the furrows. So over the centuries the ancient millers worked out the theory of why it was necessary to give the millstone furrows draft instead of running them straight out from the center. The millers also learned that the millstone dress for wheat, rye, corn or feed was different as well as the shape of the furrow effected the final product. An example is a pair of millstones mainly used to produce corn grits the bottom of the furrow is rounded instead of flat so the grits are rounded off of the kernels.

There was always disagreement among millers about the pattern for millstone dressing and which would work the best. Oliver Evans insisted that the cutting edges of the grooves be sharp and well defined. "A dull stone," he wrote, "Kills or destroys the lively quality of the grain, that causes it to ferment and raise in baking; it also makes the meal so clammy it sticks to the cloth and chokes up the meshes in bolting (sifting screens)."

Originally the miller's practiced a method of milling known as "low grinding" or "flat grinding," were the millstones were close together with a lot of speed and pressure upon the grain. The idea was to produce as much fine white flour in a single grind. Regrinding was avoided because of problems in refeeding with the conventional damsel and shoe feed system to handle the small particle size. A silent feed system would be used the the damsel was replaced by an auger drawing the material out of the hopper. Regrinding was also avoided because of heat generated problems and a conventional pair of millstones was not set up with the dress and operating speed. This produced very hot damp flour and meal and also meant that the millers always had to have their millstones dress sharp. Oliver Evans suggested mixing whole with with the middlings in this method of regrinding. Later in the mid-1800's they developed "high grinding" or "half-high grinding" where the millstones were farther apart for a lighter treatment. The idea was to produce middlings and not all of the white flour in a single grind. The bulk of your white flour comes from the regrinding of the middlings. The following grindings were done on smaller diameter pairs of middlings stones. They perhaps converted the "ending stones" of the earlier pre and Oliver Evans time that were used in a primary cleaning process and now used them in an end milling process. If you look at the Caverns Creek Grist Mill (a.k.a Howes Caverns Mill), Howes Cave, New York, and the The Rensselaerville Grist Mill, Rensselaerville, New York, these are the countries best examples of a "new process" milling operation. The smaller middlings millstones located on the second floor of the mill on a waist high platform, or it would be located in the same general area as the "ending stones" would be in an Oliver Evans automated milling system if they were located on the same level as the rest of the millstones.

Tools for dressing the millstones

Pity the poor miller who had to dress his own millstones. In Europe itinerant workers did the job while in America the miller usually dressed his own millstones. I guess then the true test of a miller may be in how he maintains the millstones. Some say that as the ground meal passes from the stones and across the miller's hands he knows instantly if it will make good bread or not before it is scooped or shoveled into barrels or sacks.

The miller knows that there should be a difference in the dress for hulling stones, splitting or cracking stones, wheat stones, middlings stones and vertical burr stones. A good miller or millstones dresser also knows how to give the stones a "quick dress" or "fix her up" so he does not have to spend the complete long process and time involved in dressing the millstones. He also knew that speed was a factor in the quality of the grain. This is why water and wind ground flour and meal has a better quality that the fast speed of the modern burr mills. The miller may have apprenticed for years to gain the practice and experience to become a good miller. In the beginning the apprentice would spend much of his time doing jobs the older millers would gladly give up such as cleaning of the mill and the machinery, bagging and packaging of products, lubrication, maintenance and repair of the machinery within the mill. The real down and dirty jobs found in a mill. Then after the apprentice mastered the jobs that would drive someone out of the door then he would concentrate on learning the real art of his trade process of milling with millstones. A great part of his time was spent in just learning how to dress and handle the millstones in grinding.

The Real Deal About Millstones (Millstones become Folklore)

The reason that millstones left a mill were: they wore out, got too thin for grinding and lift up and float, and they cracked or broke. Another reason in a time period when people had more superstitions than sense, because they were considered unlucky or evil. Until the 1700's millers did not have cranes in a mill to move and lift the millstones for dressing. So people lifted and flipped them with large wedges and pry bars. If you dropped them they would end up in the mill's basement taking out everything downward in its path. So for a long time millstones that hurt or killed any one were considered unlucky or evil, like a wild animal in a cage. Once it tasted human blood, it would wait around to attach some one at the next chance it had. So perfectly good millstones were retired out of the mill and became tombstones to mark the graves of the last person they killed. They also became door steps so others would step on them and carry their evil away with them. So for a long time a millstone removed for a mill meant that it was evil or had killed someone. The worn out ones or broken ones would end up in new bridge abutments or rebuild mill dams. Napoleon when he was marching around France was surprised by how many old broken millstones were used in bridge abutments.

A drawing from one of the HABS sheets

The French millstone material was so value to make millstones it was never used as a building stone or anything else. One of the American companies that imported French millstones, B.F. Star of Baltimore claimed in their ads that they had 2,000 men working in French quarries just making blocks to be imported to America. Other than a merchant mills that would have French millstones, mills that did combination milling would have one pair of French millstones for making white flour and another pair of domestic millstones for making corn meal, buckwheat flour, etc. A good example of this is George Washington's Grist Mill at Mount Vernon, that was a plantation or estate mill. It had one pair of French millstones for the export flour trade and one for domestic use for the people on the estate.

It is more of a modern era thing when millstones became obsolete that they were retired out of a mill and became items of decoration than used for grinding. We have short memories when it comes to things old or what is really should be termed nostalgic. This is not to mention that some did later become tombstones for millers who spent their life working in a mill and wanted to be remembered for that or somehow in the after like they are still under the weight of a millstone like having the weight of millstone around your neck. People and restored mills have collected them and the best place to store them is usually outside under cover.

Several hundred years ago an average pair of millstones costs 100 dollars for a new pair. The French millstones cost 300 dollars on the average but they were would last three times longer, but were harder to dress. Before the revolution French millstones were solid. The supply of English millstones were cut off and the American millers switched to using French millstones. They were the best stone ever discovered for grinding wheat and producing white flour. The French millstone holds its furrows or cutting edges much better that would scrape the bran off in one large flake so the inside could more easily be reduced down into the particles of white flour. Other millstones are softer and would tend to break the bran into smaller particles which would be then harder to sift out and separate the brown from the white. This is why tradition breads ground with English, German and American are brown. White flour was finer and it demanded a higher price, the brown stuff (bran and middlings) had problems in storage and keeping. It absorbed moisture, mildew, turned rancid more quickly and attacked insects and had a shorter storage life.

The United States became the largest importer of French millstones in the world. There were more here than in France or any where else in the world. The two wars we fought with England caused us to get away from anything that was English this also included the use of English millstones. During the time period of the American Revolution to the War of 1812, or 1775 to 1825 the deposits of blocks they were quarrying and became smaller so the French millstones were made out of blocks. There are only one or two pairs of solid French Millstones in the US today. It was also during this time period of Oliver Evans many mills gave up the traditional custom milling and switched to merchant milling of white flour for profit and export. The Napoleonic wars raise the price of a barrel of flour from 4 dollars to 11 dollars. Exporting flour was always one of our top 10 American industries. The silly wars of European made the American millers made lots of money.

The folklore about French millstones says that they came to American as ship's ballast, taken out of ships holds and then made into millstones. The reality is that they were shipped to America with a "ballast" rate of shipping. Another folklore about the French millstones is that because of the pours they could really grind grain without out being dressed, this may or not be true. Where I come from in northwestern Pennsylvania, if a mill has French millstones, we would say that they have "froggies in the mill." Because we associated the French with eating frog legs. Others would say that "you have a Frenchman in the mill." When dressing the millstones the hardness of the French burr would often cause small flakes of metal to break away from the point of the mill pick, some of these would become embedded in the backs of millstone hands and fore arms. If it was not removed it cause a bluish discoloration of the skin much like a tattoo. It was possible to tell from an examination of his hands, just how much experience the millstone dresser had of dressing millstones, but at lease he had done it before. Hence the phrase "show us your metal, mettle! Are you worth your mettle?

The English who came to America brought the English millstone, and the Dutch and German brought the German millstones. The first pairs of French millstones brought to America were in 1620 to Virginia for a windmill. The first water mill in the new world was at Annapolis Royal in Canada in 1599. The Spanish also had wind and water mills mainly for the sugar industry. Before the 1500's the average diameter of a pair of millstones was 72 inches and during that time they discovered bigger was not better, and the standard diameter became 48 inches. The Swan, the Dutch windmill in Holland, Michigan, has two pairs of millstones 72 inches in diameter. So there is lot of power behind the wind to operate two pair of millstones of that diameter. The windmill was the last that they would allow to leave Holland in 1965 before they were all considered national treasures.

A bed millstone with a proof staff, trammel and damsel

Up until 1890 most of the flour in America was still made with millstones. Afterwards most of the flour was made with the modern roller milling system. Mills that make Kosher flour do not use French millstones because the balance rynd (the metal bar that is across the eye opening in the center of the millstone) is cemented in place with lead. With this recent health craze wave more and more millstones are being used once again to grind flour and meal. There is always the danger that a mill will run tons of grain between a pair of millstones that are so widely space apart that the can not possibly grind the grain. But because the grain has passed between the millstones at one point in the milling process they can still label the bag as "stone ground," but it may be actually milled with the roller mills. Some times it may actually be ground with a feed mill grinder called a hammer mill if they have a set of fine screens that no one would hopefully know the difference. Many larger mills have one or two pair of electricity driven millstones to grind stone ground flour. One mill in North Carolina has 4 pair of millstones that grind 24 hours a day, 7 days a week making nothing but corn meal. The combination mill-bakeries that have spring up across the country use electrically driven smaller pairs of vertical millstones to grind organically grown stone ground flour and meals. Because the stone grind retains more of the natural goodness and flavor of the grains. Technology has not found a better method of grind flour or meal than the use of millstones or metal rollers.

Sources of More Information on Millstones:

"French Millstones," by Owen Ward, Bibliotheca Molinologica Serice Volume number 11, 75 pages, 1998, The International Molinoligical Society (TIMS).

The Journal of the Lancaster County Historical Society, Vol. 55, 1951, No. 3 "Old Millstones," by Paul Flory, pages 73-86, and No. 5, "Millstones and Their Varied Usage," by Paul B. Flory, pages 125-136. Available from the Lancaster County Historical Society.  Their web site is

"The Versatile Millstone Workhorse of Early Industry," author Jon Sass discusses the uses of millstones over the centuries using text, photographs and drawings. Includes flint, grain, hemp, chocolate, paint, querns, tanbark, edge runners, saddle stones, and many other uses of millstones; hints on millstone dressing; fully annotated, 80 pages, glossary, bibliography, 40 figures, 1984, The Society for the Preservation of Old Mills (SPOOM). Available from the SPOOM The Mill Bookstore.  Their web site is   This book is based upon the collections and writings of Paul B. Flory.  He had a collection of some 200 different types of millstones, when he retired and moved to Florida he divided up his millstones between the Smithsonian Institution and the Flowdew Hundred Plantation (Museum), Hopewell, Virginia.

"Millstone Manufacture in Virginia," edited by Charles Hockensmith. Available from the SPOOM The Mill Bookstore.

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Copyright 2001 by T. R. Hazen