Editing Gunpowder (section)

== Granularity ==

=== Serpentine ===

The original dry-compounded powder used in 15th-century Europe was known as "Serpentine", either a reference to Satan{{sfn|Nolan|2006|p=365}} or to a common artillery piece that used it.{{sfn|Kelly|2004|p=58}} The ingredients were ground
together with a mortar and pestle, perhaps for 24 hours,{{sfn|Kelly|2004|p=58}} resulting in a fine flour.  Vibration during transportation could cause the components to separate again, requiring remixing in the field. Also if the quality of the saltpeter was low (for instance if it was contaminated with highly [[hygroscopic]] [[calcium nitrate]]), or if the powder was simply old (due to the mildly hygroscopic nature of potassium nitrate), in humid weather it would need to be re-dried. The dust from "repairing" powder in the field was a major hazard.

Loading cannons or [[Bombard (weapon)|bombards]] before the powder-making advances of the Renaissance was a skilled art. Fine powder loaded haphazardly or too tightly would burn incompletely or too slowly. Typically, the breech-loading powder chamber in the rear of the piece was filled only about half full, the serpentine powder neither too compressed nor too loose, a wooden bung pounded in to seal the chamber from the barrel when assembled, and the projectile placed on.  A carefully determined empty space was necessary for the charge to burn effectively. When the cannon was fired through the touchhole, turbulence from the initial surface combustion caused the rest of the powder to be rapidly exposed to the flame.{{sfn|Kelly|2004|p=58}}

The advent of much more powerful and easy to use ''corned'' powder changed this procedure, but serpentine was used with older guns into the 17th century.<ref name="Guilmartin2003">{{cite book|author=John Francis Guilmartin|title=Gunpowder & galleys: changing technology & Mediterranean warfare at sea in the 16th century|year=2003|publisher=Conway Maritime Press|isbn=978-0-85177-951-5 |pages=109–10, 298–300}}</ref>

=== Corning ===

For propellants to oxidize and burn rapidly and effectively, the combustible ingredients must be reduced to the smallest possible particle sizes, and be as thoroughly mixed as possible. Once mixed, however, for better results in a gun, makers discovered that the final product should be in the form of individual dense grains that spread the fire quickly from grain to grain, much as [[straw]] or [[twig]]s catch fire more quickly than a pile of [[sawdust]].

In late 14th century Europe and China,{{sfn|Andrade|2016|p=110}} gunpowder was improved by wet grinding; liquid such as distilled spirits{{sfn|Kelly|2004|p=61}} were added during the grinding-together of the ingredients and the moist paste dried afterwards. The principle of wet mixing to prevent the separation of dry ingredients, invented for gunpowder, is used today in the pharmaceutical industry.<ref>Molerus, Otto. "History of Civilization in the Western Hemisphere from the Point of View of Particulate Technology, Part 2," ''Advanced Powder Technology'' 7 (1996): 161–66</ref> It was discovered that if the paste was rolled into balls before drying the resulting gunpowder absorbed less water from the air during storage and traveled better. The balls were then crushed in a mortar by the gunner immediately before use, with the old problem of uneven particle size and packing causing unpredictable results. If the right size particles were chosen, however, the result was a great improvement in power.  Forming the damp paste into ''corn''-sized clumps by hand or with the use of a sieve instead of larger balls produced a product after drying that loaded much better, as each tiny piece provided its own surrounding air space that allowed much more rapid combustion than a fine powder.  This "corned" gunpowder was from 30% to 300% more powerful. An example is cited where {{convert|34|lb|kg|order=flip}} of serpentine was needed to shoot a {{convert|47|lb|kg|order=flip|adj=on}} ball, but only {{convert|18|lb|kg|order=flip}} of corned powder.{{sfn|Kelly|2004|p=61}}

Because the dry powdered ingredients must be mixed and bonded together for extrusion and cut into grains to maintain the blend, size reduction and mixing is done while the ingredients are damp, usually with water. After 1800, instead of forming grains by hand or with sieves, the damp ''mill-cake'' was pressed in molds to increase its density and extract the liquid, forming ''press-cake''. The pressing took varying amounts of time, depending on conditions such as atmospheric humidity.  The hard, dense product was broken again into tiny pieces, which were separated with sieves to produce a uniform product for each purpose: coarse powders for cannons, finer grained powders for muskets, and the finest for small hand guns and priming.<ref name="Guilmartin2003" /> Inappropriately fine-grained powder often caused cannons to burst before the projectile could move down the barrel, due to the high initial spike in pressure.<ref>T.J. Rodman (1861), ''Reports of experiments on the properties of metals for cannon and the qualities of cannon powder'', p. 270</ref> ''Mammoth'' powder with large grains, made for [[Rodman gun|Rodman's 15-inch cannon]], reduced the pressure to only 20 percent as high as ordinary cannon powder would have produced.{{sfn|Kelly|2004|p=195}}

In the mid-19th century, measurements were made determining that the burning rate within a grain of black powder (or a tightly packed mass) is about 6&nbsp;cm/s (0.20 feet/s), while the rate of ignition propagation from grain to grain is around 9&nbsp;m/s (30 feet/s), over two orders of magnitude faster.<ref name="Guilmartin2003" />

=== Modern types ===
[[File:Hexagonal Gunpowder.png|thumb|upright|Hexagonal gunpowder for large artillery]]

Modern corning first compresses the fine black powder meal into blocks with a fixed density (1.7&nbsp;g/cm<sup>3</sup>).<ref>{{cite book|author1=Tenney L. Davis|title=The Chemistry of Powder and Explosives|date=1943|page=139|publisher=Pickle Partners |url=https://books.google.com/books?id=iKb2CwAAQBAJ |isbn=978-1-78625-896-0}}</ref> In the United States, gunpowder grains were designated F (for fine) or C (for coarse). Grain diameter decreased with a larger number of Fs and increased with a larger number of Cs, ranging from about {{convert|2|mm|in|frac=16|abbr=on}} for 7F to {{convert|15|mm|in|frac=16|abbr=on}} for 7C. Even larger grains were produced for artillery bore diameters greater than about {{convert|17|cm|in|abbr=on}}. The standard DuPont ''Mammoth'' powder developed by Thomas Rodman and [[Lammot du Pont]] for use during the [[American Civil War]] had grains averaging {{convert|0.6|in|mm|abbr=on|order=flip}} in diameter with edges rounded in a glazing barrel.{{sfn|Kelly|2004|p=195}} Other versions had grains the size of golf and tennis balls for use in {{convert|20|in|cm|adj=on}} [[Rodman gun]]s.<ref name="brown">Brown, G.I. (1998) ''The Big Bang: A history of Explosives'' Sutton Publishing pp. 22, 32 {{ISBN|0-7509-1878-0}}</ref> In 1875 DuPont introduced ''Hexagonal'' powder for large artillery, which was pressed using shaped plates with a small center core—about {{convert|1+1/2|in|mm|0|abbr=on|order=flip}} diameter, like a wagon wheel nut, the center hole widened as the grain burned.{{sfn|Kelly|2004|p=224}} By 1882 German makers also produced hexagonal grained powders of a similar size for artillery.{{sfn|Kelly|2004|p=224}}

By the late 19th century manufacturing focused on standard grades of black powder from Fg used in large bore rifles and shotguns, through FFg (medium and small-bore arms such as muskets and fusils), FFFg (small-bore rifles and pistols), and FFFFg (extreme small bore, short pistols and most commonly for priming [[flintlock]]s).<ref name="James2011" /> A coarser grade for use in military artillery [[blank (cartridge)|blanks]] was designated A-1. These grades were sorted on a system of screens with oversize retained on a mesh of 6 wires per inch, A-1 retained on 10 wires per inch, Fg retained on 14, FFg on 24, FFFg on 46, and FFFFg on 60. Fines designated FFFFFg were usually reprocessed to minimize explosive dust hazards.<ref>Sharpe, Philip B. (1953) ''Complete Guide to Handloading'' Funk & Wagnalls p. 137</ref> In the [[United Kingdom]], the main service gunpowders were classified RFG (rifle grained fine) with diameter of one or two millimeters and RLG (rifle grained large) for grain diameters between two and six millimeters.<ref name="brown" /> Gunpowder grains can alternatively be categorized by mesh size: the BSS [[Mesh (scale)|sieve mesh size]], being the smallest mesh size, which retains no grains. Recognized grain sizes are Gunpowder G 7, G 20, G 40, and G 90.

Owing to the large market of antique and replica black-powder firearms in the US, modern [[black powder substitute]]s like [[Pyrodex]], Triple Seven and Black Mag3<ref name=Wakeman>{{cite web |last1=Wakeman |first1=Randy |title=Blackpowder to Pyrodex and Beyond |url=http://www.chuckhawks.com/blackpowder_pyrodex.htm |access-date=31 August 2014}}</ref> pellets have been developed since the 1970s. These products, which should not be confused with smokeless powders, aim to produce less fouling (solid residue), while maintaining the traditional volumetric measurement system for charges. Claims of less corrosiveness of these products have been controversial however. New cleaning products for black-powder guns have also been developed for this market.<ref name="James2011">{{cite book|author=Rodney James|title=The ABCs of Reloading: The Definitive Guide for Novice to Expert|year=2011|edition=9|publisher=Krause Publications|isbn=978-1-4402-1396-0|pages=53–59}}</ref>