Blackpowder 101

As skirmishers and shooters, we all use blackpowder as a propellant in our shooting irons. But, how much do we really know about blackpowder? I wonder if, at times, we just don't take blackpowder for granted. This month, I want to take a thorough look at just what blackpowder is, how it has changed over the years, and how it works when we use it.

The Chinese are credited with having been the first to use a physical mixture of Potassium Nitrate - KNO3 - carbon and sulphur. Written records exist dating the earliest use of black powder to China circa 700 B.C. This same formula was described by the monk Marcus Graceus in his treatise Liber Ignium, first published in 848 A.D. This publication predates the exploits of Marco Polo, is sometimes credited with introducing blackpowder to Europe. Other noted publishers of information about black powder in the Middle Ages include Aderne (circa 1350), Whitehorne (c. 1560) and, later, Bishop Watson (c. 1781) and Roger Bacon. Bacon's description of the formula for blackpowder was a carefully worded anagram, for he feared that the uneducated might fall privy to the secret of the destructive power of the composition.

Early blackpowder was a coarse physical mixture that did not transport easily. Movement of blackpowder over medieval roads built with out comfort or safety standards resulted in the mixture separating itself into layers of the three components. Blackpowder was mixed for use in the immediate vicinity of the ordnance to be employed, and was meant to be used as quickly after mixing as possible. This early blackpowder (c. 13th Century) was extremely hydroscopic, however, the first improvement made to blackpowder was the discovery that coating the particles of the mixture with graphite significantly reduced this potential to absorb airborne moisture.

Metallurgy of the Middle Ages did not produce strong cannons. Probably as many cannoneers were killed by bursting of their own guns than casualties of enemy fire. Most early cannons and mortars were cast of elemental metals, not alloys. Alloys blend the strength of two elements together, resulting in better ordnance. But the artillery of the Middle Ages used such a weak method of producing black powder that strong tubes were not considered necessary at first. As the Dark Ages came to a close after the middle of the Second Millennium, experiments resulted in the production of much purer saltpeter -KNO3 - than previously possible. However, most ordnance simply could not tolerate more efficient, more powerful blackpowder.

By about 1450, most blackpowder used a standard formula of 50% saltpeter, 25% carbon and 25% sulphur, and was produced by pulverization. This mixture was, and still is, known as "Serpentine Powder." Serpentine Powder produced more than enough energy and burn at a fast enough rate for the guns of it's day. As stronger alloys began to be used in the production of ordnance, however, the limitations of Serpentine Powder became evident.

In the vicinity of Nuremburg, about 1450, an improved method of mixing the components of blackpowder developed, based on French experiments from the previous century. The basic ingredients of saltpeter, charcoal and sulphur are mixed with water to form a thick paste. The application of mechanical energy, in the form of large hammer blows or the grinding action of large wheels, results in a much more intimate mixture of the components than in Serpentine Powder. It was also discovered that the determining factor of the size of the blackpowder grains was determined by the length of the mixing time. The sheets of the mixture, when almost dry, are manipulated and crumbled into little pieces that give this type of blackpowder it's distinctive, agriculturally sounding name - Corn Powder. (NOTE: "Corn" at this time was a label given to the predominate cereal grain of a region, not maize). The dried Corn Powder was usually glazed with graphite to reduce absorption of air moisture, improve flow characteristics (Serpentine Powder had to be carefully rammed to avoid ignition!) and reduce the tendency of stored powder to cake together.

Corn Powder has several advantages over Serpentine Powder. Corn Powder burns at least twice as fast as Serpentine Powder. This meant elimination of back-venting through the barrel touch-hole, a power robbing phenomena of Serpentine Powder. Corn Powder also burns cleaner and leaves less residue that Serpentine Powder.

In spite of the chemical advantages of Corn Powder, Serpentine Powder maintained supremacy over Corn Powder for many decades. Before 1560, however, the English were experimenting with the use of Corn Powder in small arms. Gradually, better production methods of artillery meant stronger barrels and Corn Powder replaced Serpentine Powder as the propellant for ordnance.

Chemists employed by Napoleon discovered that mixing particles that were hexagonal in shape and had a central hole created greatly improved combustion characteristics of blackpowder. This design allowed slower releases of gas with out impeding combustion, creating lower pressure levels at ignition and a flatter response curve. With the flatter response curve, more powerful formulas of composition could be developed, and Modern Blackpowder was created. Modern Blackpowder has a formula of 75% KNO3, 10% sulphur and 15% carbon. Interestingly, the central hole/hexagonal shape is still employed in many smokeless powders of today.

Serpentine Powder is only 57% as powerful as Modern Blackpowder, and Corn Powder is 75% as powerful as Modern Blackpowder. All powder manufactured today closely resembles the modern formula. Blackpowder's burn characteristics are severely affected by temperature; the speed at which blackpowder burns increases as the temperature increases. In propellant charges, the temperature of blackpowder easily exceeds 2000 degrees Celsius. This rapid increase in temperature results in a time line for complete combustion of about .01 seconds. Open air combustion of identical charges is significantly slower. This rapid increase in temperature inside of our skirmishing arms also provides the cattylst for the production of harmful chemicals from the components of blackpowder. The sulphur in the blackpowder, when heat is applied, combines with moisture in the air to form H2SO4 - sulfuric acid. That is why careful cleaning of our arms is so important as soon after use as possible.

Well, that's a lot of history - 2700 years of blackpowder production and use. Soon, I'll be covering exactly how long is too long to keep blackpowder loads around, and maybe a few other interesting blackpowder topics. Until the next time, promote responsible gun ownership, shoot safe and have fun.

2000 by Tom Kelley

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