Granulation is determined by size..A predetermined screen size through which grains will fall. 1fg., 2fg., 3fg.,,,
grade is determined by the granulations finish and polish,,and/or the chemical nature.
The nitrates can be raw or refined. The charcoal can be from "oak" or "alder"..The processor or maker of the powder has his choice of what grade powder they/he wants to make available,,yet it must be listed by granulation size..
Bill Knights dissertations are still available on line through several sites. I hope that all here seek that knowledge. And spend the time to read it,.
he's a chemist,,,thus mad monk,,if you know history. Mr. Knight is responsible for the better grade of powders we have available today.
I FOUND A LINK::::::
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Welcome to Madmonks black powder pages.
courtesy Of THUNDER RIDGE Muzzloading::
A Brief History of Black Powder Production
The exact length of time in which black powder has been produced is unknown. It's use as a propellant is documented in the 14th century in both China and Europe. The use of what we know as black powder as a firearms propellant occurs in both Europe, Turkey and China within a span of about 20 years.
Black powder production evolved over a long period of time that reached a peak in both quantity and quality by the latter half of the 19th century. This evolutionary process included improvements in ingredient purity and methods of processing. Advances in powder?making technology lead to a greater number of applications for the product. By the mid?16th century, black powder was beginning to be used as a blasting agent in mining operations.
As a firearm propellant, black powder reached it's peak in quantities produced and product quality between 1850 and 1890. Black powder manufacturers were then faced with the introduction of other explosives and propellants that caused a decrease in demand for black powder and at the same time forced the industry to begin reducing the cost of producing black powder.
Prior to the early years of the 20th century black powder manufacturers purchased ingredients in what would best be described as a raw form. They then refined these ingredients, or prepared them, to their own specifications. The early years of the 20th century saw changes in sources of raw materials and the methods by which they were produced. In some instances the powder?maker was forced to change sources of raw materials even though it might result in a small compromise in powder quality. Powder?makers also had to change raw material sources as a means of reducing production costs.
Black powder manufacturing had always been a very labor intensive industry. The rise of labor costs in the early years of the 20th century resulted in changes in production methods to reduce the number of man?hours required to produce a pound of powder. These changes also resulted in some compromising of product quality.
Types Of Small?Arms Black Powder
During the 19th century there were 3 types of black powder in use in small?arms. Each type was specifically produced to give optimum performance in a particular caliber range.
Sporting powder.
Sporting powders were generally used in the smaller caliber arms. This included round?ball guns up to approximately .45 caliber. Sporting powders were low density powders with very fast burn rates. Sporting type powders continued to be used in the smaller pistol cartridges. Sporting powders were generally loaded at "one grain per caliber", or less. A sporting powder would give diminishing returns above one grain per caliber.
Rifle powder.
Rifle powders were used in round?ball guns between .45 and .54 caliber. A rifle powder gives diminishing returns at about 1.4 to 1.5 grains per caliber. Rifle powders were used in a number of rifle and pistol cartridges. A rifle powder does not burn as fast as a sporting powder.
Musket powder.
Musket powders were used in round ball guns larger than .54 caliber, muzzleloading long guns using elongated projectiles and black powder cartridges .45 and larger. Musket powders gave diminishing returns at 1.5 to 1.6 grains per caliber.
To explain point of diminishing returns, powder type and charge volume.
When you work up a load in a muzzleloading firearm, using black powder, you make incremental increases in the volume of powder charged to the bore. A point is reached where the incremental increase in powder produces less velocity increase compared to previous increases. The point at which the decreased gain is noted is the point of diminishing returns. This point of diminishing returns is determined by the "expansive force" of the powder charge. The expansive force being a relationship between the volume of gases produced by the powder charge and the temperature at which the powder burns and the diameter of the bore.
Using powder charges in excess of the point of diminishing returns may cause a marked increase in bore fouling, a noticeable increase in recoil and may reduce the useful life of the barrel by increasing the rate at which the breech area metal erodes.
There were differences, between the three types, in ingredient properties, processing methods and physical properties in the finished powder.
This particle size distribution graph shows the effect of wheel-milling times on the particle size of the charcoal ingredient in black powder. Basically, longer milling time yields smaller particle sizes and therefor faster burning powder.
Sporting powder: 65 - 75% in the 2 to 10 micron size range.
Rifle powder: 50 - 55% in the 2 to 10 micron size range.
Musket powder: 35 - 45% in the 2 tp 10 micron size range.
Description of Process
The process of manufacturing black powder is a batch system in that it is processed in small batches which are then blended together at later stages in the process. The basic process is somewhat standardized with each manufacturer having only minor variations in the basic process
A. Charcoal and sulfur are combined and ground in a ball mill.
B. The required amount of potassium (or sodium) nitrate are "laid up" in the pan of a wheel mill and the required amount of the charcoal and sulfur mixture added to the wheel mill pan. The mill batch is then wetted with the desired amount of water.
C. The wheel mill is then started and the batch is worked under the wheels for a specific period of time.
D. The batch is then "lifted" from the pan and transported to the powder press.
E. After breaking up the pieces of "mill cake" the powder is laid up in press frames. The powder is then pressed for a specified period of time at a specified pressure or at a specified loss of original volume.
F. After removal from the press the press cakes are allowed to age and harden for a specified period of time or moisture content loss.
G. The press cakes are then broken into smaller pieces prior to corning (or graining).
H. The powder is then broken into grains of varying size in the corning mill.
I. Drying and glazing are carried out in rotating glazing barrels. Air is passed through the barrel to carry moisture away from the surfaces of the grains while the mass within the barrels tumbles. (Numerous variations in how this process is carried out from one manufacturer to another.)
J. The powder grains are then sorted into particular size ranges (granulations) using varying size screens.
K.. The powder is then packed in appropriate containers.
Keep in mind that this is the basic process and that different manufacturers have variations in the process that involve batch and lot blending along with variations in the exact sequence of processing.
Ingredients and Proportions
Potassium nitrate.
Potassium nitrate is used as the source of oxygen in propellant types of black powder.
Over the period of the past 100 years the source of potassium nitrate has changed several times. Presently, almost all potassium nitrate is produced by reacting potassium chloride with nitric acid with chlorine gas as a by-product. Almost every country with salt deposits is in the business of producing various potassium salts.
There are a number of processes used to convert potassium chloride to potassium nitrate via nitric acid. Some processes are more efficient than others. Published purity data shows that minimum purity is 99.0% and a maximum purity of 99.9%. The process used in Israel produces a less pure product that is then given a second pass. The product from the second pass is roughly 99.9% purity potassium nitrate with chlorides less than 350 parts per million.
I point these differences out since residual potassium chloride in black powder is what gives the powder's combustion residue corrosive properties. Black powder that is almost entirely free of chlorides is relatively non-corrosive.
Some powder-makers specify 99.5% purity potassium nitrate while others might insist on 99.9% purity. In many respects it is more important to look at what the actual impurities consist of rather than fractional differences in amounts.
The so-called standard 75 parts of potassium nitrate is not really all that standard. The Swiss presently make a rifle type black powder using 78 parts of potassium nitrate in the powder. Old French and English powder makers used 76 to 77 parts of potassium nitrate in the faster burning grades of small-arms black powder. Other types, such as blasting or safety fuse, may be formulated with 70 to 72 parts of potassium nitrate.
Sulfur.
As with potassium nitrate, the sources of commercial sulfur changed several times during the past 100 years. During the first half of this century, sulfur from the Gulf Coast replaced sulfur imported from Italy. More recently, sulfur produced as a by-product of petroleum refining began to replace Gulf Coast sulfur.
Powder-makers will alter the proportion of sulfur depending on the type of powder being produced or use fractional alterations in the formula to adjust final burn rates in the powder.
Charcoal.
While the properties of all three ingredients are important, properties of the charcoal used to make black powder are critical to what a shooter would perceive as "quality" in a black powder.
When the formula for black powder is shown as a chemical equation the charcoal ingredient will be shown as pure carbon, or C. In actuality you would not want to make a black powder using pure carbon.
Numerous types of wood have been used to make black powder and why some are better than others has been treated as something of a mystery.
Slow-burning types of black powder may be prepared from any form of cellulose, starch or sugar. In the preparation of faster-burning types, such as a musket or rifle powder, the acceptable type of woods are reduced in number. In preparing the very fast-burning sporting type powders the acceptable woods are few in number.
Cellulose is considered to be a "high-polymer" of sugar. Sugar molecules form long chains which form the basic units of structure in the cellulose. The number of sugar units forming a unit of structure in cellulose may vary from a few thousand to over one million.
Wood "cell" structure varies considerably from one species to another. The tubular "macro-structure" of wood also varies considerably.
Different species of woods produce varying amounts of lignin which acts as a binder within the macro-structure of the wood. Starches and simple sugars are often stored within the wood's macro-structure. All of these play some part in how the wood will char, the char's final properties and how the char will behave in a black powder.
The macro-structure of the wood must be fine and somewhat delicate. Wood with a thick, or heavy, structure will be difficult to grind to the particle sizes required for faster-burning types of black powder.
Ideal charcoals based on type of powder being prepared.
Sporting: In order of preference; Glossy Buckthorn Alder, Black Alder and then White Willow.
Rifle or Musket: Alder or Willow. Maple will work, but not as well.
Blasting: almost any form of cellulose, starch or sugar. (Sugar though is most hygroscopic.)
Charcoal used in black powder is not pure carbon. The char is composed of pure carbon, partially carbonized cellulose, minerals and varying amounts of phenolic-structured liquid hydrocarbons (specifically creosote).
Water.
Water is never shown as an ingredient in black powder since only trace amounts are found in the finished powder. With some powder-makers, a batch of black powder may contain as much as 10%, by weight, of water at the beginning of the wheel-milling cycle.
The purity of the water used to wet the batch of powder, during processing, it critical to the chemical stability of the powder. The use of impure water will result in a black powder lacking in chemical stability. A black powder lacking in chemical stability will loose ballistic strength and the powder grains will become weak and crumble as they loose the cohesiveness of the mass imparted by press densification. This process will occur at varying rates independent of actual storage conditions.
Powder Processing
Given space constraints I will confine the discussion to three critical areas in the powder-making process. These being; wheel-milling, press densification and drying and glazing.
Black powder is described as an "intimate mixture" of the three main ingredients. One might aptly state that wheel-milling techniques govern the degree of intimacy of the mixture in the finished powder.
While stamp mills had long been used to incorporate black powder they are no longer used on a commercial scale for a number of reasons. Wheel mills of varying size are standard in the industry.
Wheel mills are essentially "mix mullers". During wheel-milling, the particle size of the ingredients is reduced and the particles brought into intimate contact with each other. The action of the large wheels is that of pressure smearing of the batch. The weight of the wheels, combined with the smearing action, breaks down the crystaline potassium nitrate. Particle size reduction of the charcoal and sulfur is assisted by the abrasive action of the sharp edges of the potassium nitrate crystals.
In essence, the longer you mill a batch, the faster it will burn...to a point that is.
If one grinds the 3 ingredients to the required particle size range, in something other than a wheel mill, it usually results in a slow-burning black powder. Only a wheel mill is able to produce the degree of intimate contact, in the ingredients, so necessary for fast-burning types of black powder.
And here is what that is all about..........
Milling a batch of black powder, in a wheel mill, requires the addition of water to form a paste. The problem is that charcoal and sulfur particles want nothing to do with being covered in water. Sulfur and charcoal are both hydrophobic (water-hating). Charcoal rich in "volatiles" (creosote) are hydrophobic in the extreme!
If you place finely powdered sulfur and/or charcoal in water they simply float on the surface of the water. If you attempt to force the mass under the surface it will hold a large bubble of air around the mass. This hydrophobic property prevents any degree of uniform mixing or dispersal of the two within the greater mass of potassium nitrate. The charcoal and sulfur simply form clumps within the mass. The finished burn would exhibit a slow and erratic burn rate.
The pressure smearing action of the wheel mill reduces the particle size of the ingredients and strips away any film of air encapsulating the particles of sulfur and charcoal. Removal of the air film encapsulation promotes uniform dispersion within the mass and "intimate" contact between the ingredient particles.
Actual wheel-milling time is determined by the weight of the wheels, the speed of the mill, powder type being milled and the weight of the charge in the mill pan.
Press Densification
Black powder, as it comes from the wheel mill, is totally unsuited for use as a firearms propellant. "Wheel cake" is of low density and is rather friable. That is to say that it crumbles easily. To be useful as a propellant powder it must be densified and consolidated. Wheel cake has a burn rate far too fast for a propellant
Glazing and Drying
Powder press "cakes" are broken up and "grained" in a corning mill. The next step in the process is drying and glazing.
Before launching into the subject of glazing it would be best to explain that glazing has nothing to do with the use of graphite applied to the powder grains.
After pressing, the grained powder will contain varying amounts of water. The amount may vary from 1 to 2%. If the powder grains are dried on trays they will form loose deposits of potassium nitrate crystals on the surfaces of the grains. Any water migrating to powder the surfaces of the grains will do so as a saturated solution of potassium nitrate..
Press densification is little more than a compacting process. During pressing, a rifle type powder would loose about 45% of it's original volume. Sporting type powders would loose about 40% of the original volume while a musket type would loose about 50%.
Press densification will slow the burn rate of the powder roughly in proportion to the degree of densification. There is a point, however, where the burn rate drops drastically with increasing density.
Press densification imparts mechanical strength to the mass of powder. Keep in mind that 75%, by weight, of the mass is potassium nitrate. The mass being pressed is about 2% water. Wherever potassium nitrate crystals contact each other they will begin to fuse together. This fusing of contacting surfaces promotes hardness and mechanical strength.
By tumbling the grains, during drying, the crystals of potassium nitrate are compacted and fused into a thin shell, or skin, covering the surfaces of the powder grains. Under high magnification this thin skin, or shell, will give the appearance that the powder grain had been coated with glass. The appearance of the glass-like skin is where the term "glazed" powder originated. Large grains of powder will have a thicker glaze since the large grain sizes have a greater amount of mass relative to their surface area.
The thickness of the glaze formed on the grains will, in part, determine ease of ignition of individual grains of powder and govern flame spreading rates within a mass of powder grains. Heavy glazing slows the process of
ignition and combustion of the powder. Heavy, or thick, glazing was used to slow powder charges behind heavy projectiles.
When high-purity potassium nitrate is used to fabricate the black powder the glaze imparts a degree of moisture resistance to the powder grains. Below 90% relative humidity the powder will be little effected by water vapor in the air. Above 90% R.H. the powder grains will pick up only trace amounts of moisture which will be quickly passed back to the air when the R.H. falls below 90%.
NOTES
During the 19th century the type of powder used in a specific type of small-arm depended on it's caliber and projectile mass. The powder type, in turn, determined the rate of twist in rifled arms shooting round balls.
Sporting type - Used in round-ball guns up to .45 caliber. Used at 1 grain per caliber, or less, i.e., 45 grains in .45 caliber bores. Also used in the smaller pistol cartridges. Sporting powder, more often than not, would be found in a grain size best described as an equal mixture of our present 2f and 3f granulation sizes. The rate of twist in a rifled round-ball barrel would be 1 turn in 48 inches.
Rifle type - Used in round ball guns larger than .45 caliber but smaller than .58 caliber. Used at roughly 1.4 to 1.5 grains per caliber. Used in numerous black powder cartridges. A .45 caliber bore would call for 60 grains of powder. This powder type was also generally found as an equal mixture of our present 2f and 3f. The rate of twist in a rifled round-ball gun would be 1 turn in 56 or 1 turn in 60 inches.
Musket type - Used in .58 caliber, and larger, round ball guns. Also used extensively in cartridge rifles. A .45 caliber would give a point of diminishing returns of 70 grains of powder, hence the .45-70 cartridge. Prior to the introduction of elongated projectiles it was usually found as an equal mixture of 1f and 2f. After the introduction of elongated projectiles it was used in a straight 1f size in some arms while the equal mixture of 1f and 2f continued to be used in other arms. In a rifled round-ball gun, the rate of twist would be 1 turn in 70 inches.
Special powders.
While the production of musket powder is thought to have ceased at the end of the American Civil War it continued in production as a "special" powder supplied to commercial cartridge loading companies.
Grain size variation.
The standardization of grain sizes began in first half of the 19th century. Numbering systems were, however, far from standardized. With one powder manufacturer, grain size designations were backwards from the norm to certain customers.
Black Powder Bore Fouling
Part 1. Bore fouling and humidity.
When one reads books on shooting black powder firearms there is usually a comment made that black powder residue is hygroscopic. Given as a flat statement of fact, without mention of this
occurring in degrees.
Lyman Black Powder Handbook
Copyright 1975
Page 60. Cleaning Your Black Powder Firearm
"This blackpowder fouling is hygroscopic ? it absorbs moisture from the air abnormally fast."
Philosophical Transactions Of The Royal Society Of London For The Year 1875
Vol. 165 ? Part 1
Researches on Explosives. ? Fired Gunpowder
Capt. Noble and F.A. Abel
Read June 18, 1874
Page 67.
2. Solid Residue ? Preparation of the Residue for Analysis.
"The impossibility of pulverizing and mixing the residue by any ordinary mode of proceeding, on account of the rapidity with which oxygen and water were absorbed from the air, was demonstrated by two or three attempts."
Page 68.
C. Water contained in the residue. ? "It is obvious that the highly hygroscopic nature of the powder?residue rendered it impossible to transfer the product of an explosion from the cylinder to suitable receptacles for its preservation out of contact with the atmosphere without some absorption of moisture, however expeditiously the operation was performed."
The need to take a close look at the hygroscopic behavior of black powder bore fouling, or residue, became evident in the Fall of 1999 and both the Spring and Fall of the year 2000. On certain days of shooting the bore fouling would be seen as a thick coating of dry powdery fouling in the bore while the next day the bore fouling might be moist and paste?like with the same can of powder being used in the gun. With the dry powdery bore fouling it was nearly impossible to reload the rifle without running a wet cleaning patch down the bore. Damp patches would do little more than pack the dry powder into a hard cake in the bore. Only very wet patches would give a clean bore. A brand of patch lube that previously had worked flawlessly in reloading without having to wipe the bore suddenly seemed not to work at all.
From late Sept. 200 through mid?Dec. 2001 shooting days were selected by weather conditions to give a range of temperature and relative humidity to observe how the weather influenced the bore fouling in the rifle.
By watching the consistency, or "texture" of the bore fouling and both the air temperature and the relative humidity a pattern began to evolve.
If the relative humidity was 30%, or lower, the powder residue in the bore would be dry and powdery. Pressure applied by a damp cleaning patch, or by a patched round ball in reloading without wiping, the bore fouling would be compacted into a hard cake that adhered strongly to the bore surfaces. If the relative humidity was above 40% the bore fouling would be moist. The degree of moistness increasing with increases in the relative humidity.
In this work it became clear that the black powder fouling exhibited this hygroscopic property in varying degrees. The shooting results were compared to both the temperature and the relative humidity in regards to the amount of water present in the air in terms of grains of water per cubic foot of air. There is a great difference in the amount of water in the air when one compares 30% R.H. at 30 degrees F verus 30% R.H. at 70 degrees F. But the results showed that the hygroscopic behavior did not reflect changes in the actual amount of water in the air at a given level of relative humidity at a given temperature. The only relationship that could be seen was the percent relative humidity. That appeared to be the only factor involved.
So then it was back to the works of Noble & Abel to look at what chemical compounds are present in black powder bore fouling. Work on the pH of black powder residue showed the presence of potassium carbonate, or potash. The gunpowder residue analysis work of Noble & Abel shows that the major portions of the solid residue consists of potassium carbonate and potassium sulfate. The exact proportions of these in the residue will change somewhat with the brand of powder being used and the temperature at which the powder burns. But in any case there is a greater amount of potassium carbonate compared to potassium sulfate. Roughly 3 to 4 times as much potassium carbonate as potassium sulfate.
To then view how potassium carbonate governs the hygroscopic behavior of black powder residue a shallow dish containing pure potassium carbonate was placed outside under a roofed over deck. As the relative humidity changed with changes in the weather the potassium carbonate was observed. It was found that when the relative humidity was 30% or below the potassium carbonate would be a dry white powder. As the relative humidity rose above 30% the potassium carbonate would become damp. At 40 to 60% relative humidity the potassium carbonate would form a paste?like mass. At 80% relative humidity the potassium carbonate began to liquify.
What this showed was that at 30% R.H., or less, the potassium carbonate was for all practical purposes non?hygroscopic. From 30% R.h. to 60% R.H. the potassium carbonate could be classed as being hygroscopic. Above 60% R.H. the potassium carbonate would be classed as being deliquescent in nature.
According to the work of Noble & Abel, unless a black powder is specifically formulated and processed to be a "moist?burning" powder it will produce no water as a product of combustion.
This information was tested by flashing 500 grains of two different brands of black powder, in 10 grain increments, in metal salve tins. These were capped and weighed as soon as the last increment had been flashed . These were then placed in an oven at 150 degrees F for an hour to check for any weigh loss. Then an additional hour at 250 degrees F. No weight loss that would be indicative of any moisture loss was observed.
In putting all of this together. Except for the Swiss?made black powder, none of the black powders currently on the market produce water as a product of powder combustion. They will therefor produce a dry fouling in the bore. Any moistening of the bore fouling comes about when the spent powder gases leave the bore after the projectile leaves the muzzle. This results in a rapid inrush of atmospheric air into the bore. This "fresh air" then becomes a source of water for any moistening of the bore fouling. With the potassium carbonate portion of the bore fouling determining how much water could be pulled from this air.
An Important Aside.
The work on the hygroscopic nature of black powder fouling raised other issues in this work. Most importantly, after?rusting in the bore of the gun. One will see claims for patch and bullet lubes that eliminate bore fouling, eliminate rust and corrosion and black powder substitutes that are non?corrosive.
NEVER take such claims as 100% factual.
In the work on the hygroscopic properties of black powder bore fouling we see the fouling as being non?hygroscopic at 30%, or less, relative humidity. That also means that the bore fouling will be almost non?corrosive at a relative humidity level of 30% or less. If the bore fouling does not pick up moisture there can be no rust. The rusting or pit corrosion in the bore is an electrolytic corrosion which requires the presence of a minimum amount of water present in the bore fouling. So while a gun might be left with a fouled bore one time with no signs of rusting the same might not be true on another day where the humidity is high enough to cause the fouling to pick up moisture.
One will see a claim that when a black powder substitute does not contain sulfur there will be no sulfur corrosion. In actuality, sulfur is not the corrosive agent in black powder. Gun bore "corrosion" may be promoted by two chemical compounds. If the potassium nitrate used in the powder, black powder or any of its substitutes, you may see chloride pit corrosion in the bore if the potassium nitrate contained any residual potassium chloride. Potassium carbonate, in itself, will cause the formation of thin surface films of rust on unprotected ferrous metals. As long as the propellant powder uses potassium nitrate in the formulation it will produce potassium carbonate as a product of combustion. So when it comes to hygroscopic properties and the possibility of after?rusting the various black powder substitutes should be treated as one would treat the use of black powder in a gun. They all have the ability to damage a bore under the right conditions. Never leave the bore fouled for any length of time and always watch for signs of rusting on cleaning patches when setting the gun up to shoot after a period of storage. Rust is not always
red. When mixed with a patch lube the rust may well show up as a brown stain on the cleaning patch used to prepared the bore for shooting.
Part 2. Amounts of bore fouling.
The work of Noble & Abel shows that if you burn 100 grains of black powder in the bore of the gun the weight of the gases produced will be about 45% of the original charge weight while the weight of the solid particulate matter produced will be about 55% of the original charge weight.
So in dealing with bore fouling, how does this information relate to what a shooter would expect to see in regards to weight of bore fouling? When the gun is fired, some of the solid matter from powder combustion will be retained in the bore while some is ejected from the bore in the spent propelling gases that exit the bore following projectile exit.
The work of Noble & Abel shows that almost all of the solid matter produced by powder combustion are water?soluble in nature, that only a fraction of a percent are water?insoluble.
Past shooting experience had shown that if a between shot cleaning patch is wet, versus just damp, all of the residue in the bore will dissolve into the water held in the patch if the patch is run down the bore slowly, leaving the bore almost squeaky clean. This phenomenon might then be used to measure the weight of fouling found in the bore of the
gun after firing a charge of black powder.
In reviewing black powder information sources from the 19th century through to present, nothing was located that gave any data on how much bore fouling would be found in a bore shooting black powder. All of the information relative to bore fouling was subjective in nature. As was pointed out in Part 1, on one day a can of powder might well look like the worst powder ever produced and on another day, under different conditions of climate, look like a fairly good powder.
So the goal became one of quantifying the bore fouling to eliminate at least some of the subjective judgement of variations in bore fouling with different powders under different conditions of climate.
For this work, cleaning patches made from a non?woven cellulose fiber with a deep waffle embossing were selected based on their ability to retain a large amount of water, compared to other types of fabric. Trials showed that when used properly they would pick up almost all of the fouling found in the bore.
The basic test method became one of weighing 10 of these patches which were then placed in packets made from aluminum foil. After each round fired a patch would be removed from the packet, saturated with water and then used to slowly swab the bore after each round. Upon removal from the muzzle the used patch would be placed in an appropriately marked aluminum foil packet. After ten shots and ten patches, the packet was closed and placed in a baggie. Upon arrival home these foil packets would be opened and placed in the oven at 250 degrees F until constant weigh, or total dryness. Then weighed with the weight being recorded. The weight increase from the original being the amount of fouling recovered from the bore with 10 shots given an average weight of recovered bore fouling per shot. Knowing the weight of the powder charged, it is then possible to calculate the recovered fouling as a percentage of the original charge weight.
`Trials showed that this method produced a reasonable degree of accuracy. Considering that nothing such as this has been published to date it was considered a giant step forward in understanding black powder behavior.
The first work with this method of measuring bore fouling involved a look at 3 years production of Elephant black powder. Knowing the little differences in the formulation and processing of the three different production run there were gut feelings as to what one might find.
The test rifle selected for this work is the same rifle used to do chronograph work with 3f powders. A Tennessee Valley Manufacturing (TVM) Southern Mountain Rifle in .45 caliber with a 35.25 inch internal length barrel and a flat face breech plug. With flintlock ignition. The balls used were .440 Speer with shooting patches cut from .020" #40 cotton drill which are then lubed with Lehigh Valley Shooting Patch Lubricant.
In the first round of testing using Elephant 3Fg.
1998 production, 3.8% of the original charge weight as recovered bore fouling.
1999 production, 2.3% of the original charge weight as recovered bore fouling.
2000 production, 2.5% of the original charge weight as recovered bore fouling.
The 1998 lots of Elephant had been noted for an excessive amount of dust and fines. This excess of dust and fines contribute materially to bore fouling in the guns.
The 1999 lots of Elephant came to be known as the "factory socked" Elephant. The plant in Brazil putting a lot of effort into cleaning the powder just prior to it being packaged. They had also speeded up the burn rate from that of a musket powder to that of a rifle powder. The increased burn rate and elimination of dust and fines giving the reduction in bore fouling.
The 2000 lots of Elephant were prepared with a charcoal having a slightly higher fixed carbon content than the charcoal used in the 1999 production. As later testing showed, the 0.2% difference may reflect the slight difference in charcoal or be the level of experimental error in this type of test method. But the difference in the results shown in the 1999 versus 1998 production become clearly visible when it comes to dealing with the fouling left by the two powders.
Over the past 5 or 6 years Elephant has advertised that they were constantly making efforts to reduce bore fouling with their powder. This is simply another form of proof of that claim.
In my years of muzzleloading I have enjoyed the friendship of a number of people who are well known in muzzleloading circles. From the very beginning, Chuck Dixon was something of a mentor since I live close to his shop and purchase all of my guns and supplies through him. Over the years we have discussed various aspects of modern day muzzleloading and writings from the 19th century. Writings written in a style that often do not make sense until one digs deeply into them and what was being discussed.
Such an item brought about the next round of work.
The 19th century writings commented that when a shooter charges the gun above a certain point there will be a marked increase in the amount of felt recoil and a marked increase in the amount of bore fouling. This was there way of determining the point of diminishing returns in charge sizes with a given type of powder in a given caliber.
Using the same TVM test rifle another round of testing was set up. The 2000 production Elephant showed a point of diminishing returns at 60 grains in the .45 caliber. That means that when the charge is increased over 60 grains the gain in velocity is less than with the charge increases below 60 grains. The testing was done with an adjustable powder measure that throws 100 grains weight of water at the 100 setting. So the setting will indicate grains charged thought that would not be the exact weight of powder charged. The exact weight was taken from a graph prepared by graphing the setting verus actual weight of powder. The actual weight charged then being used in the calculations.
Measure Recovered
setting bore fouling
40 2.5% of the original charge weight as recovered bore fouling.
50 2.6% of the original charge weight as recovered bore fouling.
60 2.4% of the original charge weight as recovered bore fouling.
70 2.3% of the original charge weight as recovered bore fouling.
80 2.3% of the original charge weight as recovered bore fouling.
90 2.5% of the original charge weight as recovered bore fouling.
With 2.43% being the average. (Compared to 2.5% on another day.)
The data shows that above 60 grains (the point of diminishing returns) there was no marked increase in bore fouling. At least not by weight. But what then did the old information indicate or refer to?
The answer to that could be seen on the recovered patches and felt when the wet cleaning patch had been run down the bore. Above 60 grains there was a noticeable increase in resistance to the passage of the wet patch down toward the breech area of the bore. The recovered wet cleaning patches began to show a buildup of powder residue that was not quickly soluble in the water held by the patch. This buildup was black versus a green?black of the previously recovered bore fouling. What was changing was the consistency, or texture, of the bore fouling which made it more difficult to remove. From the standpoint of percentage of original charge weight, the increases in weight of bore fouling remained constant. The old writings were based on subjective judgements of fouling and felt resistance to the passage of the cleaning patch, or subsequent reloading without wiping, had prompted the view of an increase in bore fouling. From the view
of ramrod feel there was a marked increase in fouling. From actual weights, the increase would be uniform.
2Fg versus 3Fg.
On the Internet black powder message groups, one will see posting regarding the use of reduced charge volumes of 3Fg, replacing larger volumes of 2Fg. The common comment being that the 3Fg will produce less bore fouling and burns cleaner than 2Fg powder.
Using the wet cleaning patch bore fouling recovery method, this was investigated.
Using the same .45 caliber TVM Southern Mountain Rifle.
3Fg Elephant, Lot 054, Date Code 25/99, 60 volume measure, 65.0 grains weight.
2.8% of the original charge weight as recovered bore fouling.
2Fg Elephant, Lot 049, Date Code 25/99, 60 volume measure, 63.9 grains weight.
2.8% of the original charge weight as recovered bore fouling.
The data shows that the amount of bore fouling does not change with a change in grain size. Any reduction in the actual weight of bore fouling is strictly a point of a reduction in the amount, or weight, of powder charged to the bore.
An interesting point is to be found in comparing the above data to the first round of testing data at the top of page 6. The data on page 6 came about in shooting on a day when the ambient air temperature was lower and the relative humidity was lower. The shooting involving the use of 2Fg versus 3Fg was done a few days later when the ambient air temperature was higher and the Relative Humidity was up in the 80 to 90% range.
In comparing test data, from the same can(s) of powder it was found that the difference in bore fouling between low humidity to high humidity averages about 0.5%. These same two cans of powder gave a recovered bore fouling percentage of 2.3% on a day with low humidity.
Powder residue distribution in the bore.
This work in measuring bore fouling weight gave the ability to look at how the powders combustion residue was distributed in the bore of the rifle being used.
Numerical data.
Muzzle to 12" into the bore, 0.35% of the original charge weight as recovered residue.
12" to 24" in from the muzzle, 0.62% of the original charge weight.
24 in from the muzzle to the face of the breech plug, 1.90% of the original charge weight.
Total for the three sections was 2.87% of the original charge weight.
Physical form of the powder residue.
In this testing it was found that on a day when the air was cool, say 30 to 40 degrees F, the bore fouling appeared to be a very finely divided powder that would be packed into a hard film by the passage of a damp, not wet, patch over it. The pressure from the cleaning patch compacting the fine powder into a hard film on the bore. At this low temperature the weight of the recovered bore fouling would range from 2.3% of the original charge weight up to about 4.0% depending upon the brand of powder used and a particular lot of a particular brand.
This work was later repeated on several days where the air temperature was in the high 80's to low 90's.
This change in ambient air temperature had a very dramatic effect on the recovered bore fouling data. A can of powder that gave a figure of 2.5 to 3.0% on a cool day would give a figure of 14 to 15% on a very hot day. The previous work showed that a difference in Relative Humidity would not create this magnitude of difference.
In the work on measuring bore fouling it was understood that black powder will yield about 55% of its original charge weight as solid particulate matter as a result of powder combustion. In other words, a 100 grain charge of black powder would be expected to give about 55 grains of solids as a result of powder combustion.
So what we are dealing with here is the difference between the amount of residue retained in the bore versus the amount ejected from the bore when the projectile and spent propelling gases exit the muzzle.
The next question that had to be addressed relates to the primary governing factor that determines the amount retained versus the amount ejected.
That answer came by examined samples of recovered bore fouling recovered intact from the bore.
A bore fouling thief was devised by modifying a ramrod ferule to act as a bore scraper collecting cup. Recovered fouling samples then quickly placed in cap tins for later examination under the computer microscope.
The bore fouling thief was made using a steel ramrod ferule modified to screw into the end of the ramrod. After firing the rifle the thief is run into the bore and the gun is turned muzzle down. Powder residue scraped from the surface of the bore falls into the cup. The residue then being transferred to a cap tin for sealed storage.
The rifle used in this test was a Lyman .50 caliber Trade Rifle and the modified ferule is a snug fit in the bore, riding on the lands of the shallow-groove rifling.
The microscope photo of the recovered powder residue is one of a number of samples where increasing charge volumes were shot.
The photo shows a mixture of white beads and clear beads along with dark beads. This sample was collected after having fired an 80 grain charge of 3Fg behind a patched ball.
This work, the combination of shooting and recovered bore fouling photos, showed how ambient temperature plays a part in the amount of bore fouling in a black powder gun.
Going back to the chemical compounds found in black powder combustion residue. The major portion of the solid particulate matter being potassium carbonate.
Working in the 1860's, in England, Nobel and Abel found that the maximum combustion temperature of a cannon powder was about 1800 degrees C. The maximum combustion temperature of a sporting powder being about 2200 degrees C. Musket and rifle burn rate powders would be below that of a sporting powder and higher than that of a cannon powder. The theoretical combustion temperature of black powder is usually shown as 2350 degrees C.
Potassium carbonate, forming the major portion of the powder residue has a melting temperature of about 1630 degrees C.
The potassium carbonate is formed in the gases that surround the burning grains of powder when the charge is ignited and burns. The temperature of the gases behind the projectile will determine the particle size of the potassium carbonate found in the powder residue. At low ambient temperatures, and cool barrels, the particle size of the potassium carbonate is very small. Giving the finely divided powder residue seen during low temperature shooting.
As the temperature of the gases behind the projectile rise above a certain level there will be an agglomeration, or joining, of these particles. These massive agglomerations are seen as white beads in the microscope photo on page 10. Given a sufficiently high heat, the particles of potassium carbonate are melted and fused together forming glass-clear beads.
Working with the recovered bore fouling samples from different charge volumes a pattern was seen. As the charge volume was increased the predominance of white beads changed to a predominance of clear beads. Eventually, as charge volumes were further increased, the recovered residue looked like fused foundry slag. Very glassy in appearance and the entire mass fused.
This change in physical properties could be felt with the ramrod when swabbing the gun between shots when not recovering residue samples. A point was reached where the feeling was one of a gritty powder residue. Which then changed to a very hard ring of fouling in the breech. Same can of powder in the same gun at widely varying charge volumes (weights). The change in residue being related to the change in gas temperatures brought about by the change in charge volumes(weights).
Relating this to the difference in amounts of bore fouling found at low ambient temperatures versus high ambient temperatures.
When the gun is fired the projectile moves away from the powder charge shortly after the charge is ignited. As the projectile begins to move up the bore the hot gases produced by the burning powder are exposed to an ever increasing amount of bore surface. That results in some cooling of the gases and heating of the barrel.
In dealing with heat transfer from the gases to the bore wall metal. The rate of heat transfer is governed in part by the difference in temperature between the metal and the gases. The gases will not cool as quickly if the bore walls are hot. The temperature of the gases determining the particle size of the bore fouling and the extent of fusion in the mass of fouling.
The particle size of the fouling and the degree of fusion of the mass then determines the amount of solid particulate matter that is retained in the bore versus the amount that will be ejected from the bore with the spent propelling gases that exit the barrel once the projectile clears the muzzle. The larger particles simply cannot remain suspended in the gases long enough to be blown out of the barrel.
Part of this work involved comparing different brands of powder in the same rifle on the same day under identical shooting conditions. In terms of percentage of charge volume retained in the bore, there was no significant differences found from one brand to the next. The major differences seen involved the texture or consistency of the bore fouling and how it felt when running a damp patch down the bore between shots.
Baked fouling and bore cleaning.
The black powder combustion residue left in the bore is soluble in water and about 99% of the residue is in fact water-soluble.
The physical form of the powder residue will determine how easily it is removed from the bore.
When the powder combustion residue is in the form of a finely divided powder it will dissolve very quickly in water.
When the powder combustion residue is baked in the bore, or heat fused, it is still highly soluble in water but it is in a form with a minimum of surface area exposed to the water and it therefor becomes very slow in dissolving in the water. Patches of fouling that become fused on the surface of the bore are rather difficult to remove because the patches are bonded to the surface of the metal and will rarely slide off the metal with pressure. Removal of the baked on patches of fouling require hot water and mechanical agitation of water in the bore. This is why one time the bore will clean very quickly and easily and another time be a real chore.
January 2003
William Knight
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