B. Commercial High Explosives

 

An explosive which supports a detonation wave.

High explosives are also defined as an explosive substance or mixture which invariably detonates when initiated, irrespective of the ambient condition of confinement (i.e. in the open).

High explosives are those materials that undergo detonation without confinement, are compounds, initiated by shock, the reaction within the product is supersonic, and has a high brisance.

1. Primary Explosives

Primary Explosive, a sensitive explosive which nearly always detonates by single ignition from such means as spark, flame, impact and other primary heat sources of appropriate magnitude.

Primary explosives can detonate by the action of a relatively weak mechanical shock or by a spark. If used in the form of blasting caps (detonator), they initiate the main explosive. They are also filled in percussion caps mixed with friction agents and other components.

An initiating explosive must be highly brisant and must have a high triggering velocity. The most important primary explosives are mercury fulminate, lead azide, lead trinitroresorcinate, silver azide, diazodinitrophenol, and tetrazene, which is used as an additive in primers. Initiating charges must be transported only if they are already pressed into capsules. The latter are usually made of aluminum, and sometimes of copper, white plastic capsules are used for special purposes.

Primary explosives, have a low deflagration to detonation transition, and go from burning to detonation very quickly. They differ as to sensitivity and the shock given off. Primary explosives are reactive to different materials, care should be taken when handling primary’s that are in the natural state. Generally speaking, they will not be found in the raw form.

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a. Lead Azide

Uses – Manufacture of detonators.

Properties:

Excellent initiating agent for high explosives, more efficient than mercury fulminate.

Generally covered with Lead Styphnate for sensitivity.

Used as intermediate charge.

Good initiator for sensitive booster charges, RDX, PETN, Tetryl

Reactive to copper in the presence of moisture. Formation of copper azide, which is extremely sensitive.

Color, white to buff with rounded aggregates.

VOD: 16,745 ft/sec.

b. Lead Styphnate

Uses – Manufacture of detonators

Properties:

Lead styphnate is a poor initiator, but it is easily ignited by fire or by a static charge.

Used as priming layer which causes lead azide to explode from a flash.

Reddish – Brown crystals.

VOD: 17,000 ft/sec

c. Mercury Fulminate

Mercury Fulminate appears to have been prepared for the first time by Hohann Kunckel von Lowenstern. (1630 - 1703) The preparation and properties of mercury fulminate were described in much detail by Edward Howard in 1800 in a paper presented to the Royal Society of London. Preparation of Mercury Fulminate is carried out by a process essentially the same as described by Howard.

Uses – Manufacture of detonators

Properties:

Used as a base charge in the past.

Not used extensively

Color is White – Grey or Light Grey with a yellow tint.

VOD: 14,780 ft/sec

d. Other Primary Initiating

There are a variety of other primary initiating explosives, however, they generally will not be found in the "raw" form due to the sensitivity of the product. They will, generally, found as components in blasting caps (detonators)

Other examples include: Lead Salts of Picric Acid, Nitrogen Sulfide, Copper Fulminate, Chlorates with Red Phosphorus, Tetrazene, and DDNP (Diazodinitrophenol)

2. Secondary High Explosives

Secondary High Explosives are those explosives which are relatively insensitive, in comparison to primary explosives and are insensitive to shock, friction, or heat. They are, however cap or booster sensitive and are classified as High Explosives.

It would not be worth taking the time to discuss Secondary High Explosives without spending some time discussing the history and the impact that Nitroglycerin and Nobel had on the development of explosives.

a. Nitroglycerin (NG)

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Nitroglycerin was first prepared late in the year 1846 or early in 1847 by the Italian chemist Ascanio Sobrero (1812 – 1888) who was at the time professor of Applied Chemistry at the University of Torino. Sobrero, was authorized to practice medicine and had studied in Paris and Giessen, returning to Torino in 1845 where he equipped a laboratory. The earliest printed account of nitroglycerin appears in a letter which Soberro wrote to Pelouze and which Pelouze caused to be published in L’Institut of February 15, 1847. In the same month Sobero presented to the Academy of Torina a paper in which he described nitroglycerin, nitromannite, and nitrated lactose. Later in the year he presented another paper before the chemistry section of the Ninth Italian Scientific Congress at Venice.

Sobero found that , if concentrated nitric acid or strong mixed acid is added to glycerin, a violent reaction ensues and red fumes are evolved, but that, if syrupy glycerin is added to a mixture of sulfuric acid and nitric acid, with strict controls the results are entirely different. The glycerin dissolves, and the solution when poured into water gives an oily precipitate of nitroglycerin.

For many years Sobrero kept in his laboratory and guarded jealously a sample of the original nitroglycerin which he had prepared in 1847. In 1886 he washed this material with a dilute solution of sodium bicarbonate and took it to the Nobel-Avigliana factory, of which he was a consultant, where he gave verbal testimony of its authenticity and where it has since been stored in one of the magazines.

Nitroglycerin was the first, and is still one of the most widely produced nitrate ester. It is used in dynamites, nitroglycerine is absorbed in fine wood meal or other powdered absorbent. This process prevents the microbubbles from forming and stabilizes the liquid. The nitroglycerine is also thickened or gelantinized by the addition of a small percentage of nitrocellulose. This process assists in preventing "weeping" (exhuding) or settling out of the absorbent material. Because settling does occur, boxes of stored nongelled dynamites are turned over at regular intervals to reverse the settling flow.

Uses: Nitroglycerin is one of the most important and most frequently used components of explosive materials, together with nitroglycol, it is the major component of gelatinous industrial explosives. In combination with nitrocellulose and stabilizers, it is the principal component of powders and solid rocket propellants.

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Odor is not offensively pungent.

Color, clear, as light as possible, darker colors have impurities.

Slightly oily to the touch

Unstable and dangerous to handle.

Very sensitive to shock and when the temperature is increased it is more sensitive.

Flammable, and when heated as a result of fire it will detonate.

Vapors cause a sever and persistent headache.

Used as a Vaso dilator.

VOD: 25,000 ft/sec

b. Dynamite

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Nobel, having discovered a way to reliably initiate nitroglycerin, knew that the extreme sensitivity and difficulty in handling the liquid were very serious problems. Dynamite and the fulminate blasting cap both resulted from Alfred Nobel’s effort to make nitroglycerin more safe and more convenient to use.

Having discovered that nitroglycerin is exploded by the explosion of a small firecracker-like device filled with black powder, he tried the effect of mixing the two materials and in 1863 was granted a patent which covered the use of a liquid explosive, such as nitroglycerin or methyl or ethyl nitrate, in mixture with gunpowder in order to increase the effectiveness of the latter. The amount of the liquid was limited by the requirement that the mixtures should be dry and granular in character. The explosives were supposed to be actuated by fire, like black powder, but the liquid tended to slow down the rate of burning and they were not notably successful. The same patent also covered the possibility of substituting a part of the saltpeter with nitroglycerin. Because this substance is insoluble in water and non-hygroscopic, it acts as a protective covering for the salt and makes the use of sodium nitrate possible in the mixtures.

Nobel’s, next patent, granted in 1864, related to improvements in the manufacture of nitroglycerin and to the exploding of it by heating or by means of a detonating charge. He continued his experiments and in 1867 was granted a patent for an explosive prepared by mixing nitroglycerin with a suitable nonexplosive porous absorbent such as charcoal or siliceous earth. The resulting material was much less sensitive to shock than nitroglycerin and known as dynamite, and was manufactured and sold under the name "Nobel’s Safety Powder". The absorbent which was finally chosen as being most satisfactory was diatomaceous earth or kieselguhr. Nobel believed that dynamite could be exploded by a spark or by fire if it was contained closely, but preferred to explode it under all conditions by means of a special exploder or cap containing a strong charge of mercury fulminate, crimped tightly to the end of the fuse in order that it might detonate with more strength. He stated that the form of the cap might be varied greatly, but that its action depended upon the sudden development of an intense pressure or shock.

Prior to the issue of the patent for dynamite, production had begun in the San Francisco area. Within the next few years numerous plants were built, primarily concentrated in the San Francisco region in the west and New Jersey in the east. The original manufacturers were most entrepreneurial businessmen, with no prior connection to the explosives (black powder) industry. Soon, however, the dynamite industry came under the domination of the DuPont Company, but this monopoly of explosives manufacturing ended with U. S. Government ordering its breakup under the federal antitrust laws. The result was the establishment of the Atlas Powder Company and the Hercules Powder Company as competitors to DuPont.

The dynamite industry flourished until the late 1950’s when the US had 34 operating plants. At about that time, modern blasting agents came into wide usage and began to replace packaged high explosives. As of 1996, only one dynamite plant remained in operation on the North American continent.

Deteriorated Dynamites or Exhuded or Crystalline

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The nitroglycerin used in dynamites is also thickened or gelatinized by the addition of a small percentage of nitrocellulose. This helps prevent the liquid from "weeping" or separating from the absorbent. Because settling does occur, boxes of stored nongelled dynamites are turned over at regular intervals to reverse the settling flow. However, old and deteriorated dynamite may have exhuded allowing the liquid explosive to seep through the wax impregnated kraft paper.

Uses - Construction, Road Building, Quarrying, Mining, Destruction

Ingredients:

Nitroglycerine (NG), Ethylene Glycol Dinitrate (EGDN), Ammonium Nitrate (AN), Nitrocellulose (NC), Sodium Nitrate (SN), Carbonaceous Fuel (wood pulp & ground shells), Sulfur.

Types:

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(a.) Straight Dynamite: NG & EGDN

(b.) Ammonia Dynamite: NG, EGDN & AN

(c.) Gelatin Dynamite: NG, EG DN & NC

(d.) Ammonia Gelatin Dynamite: NG, EGDN, AN, & NC

(e.) Permissible Ammonia and Gelatin Dynamites: Added Salt

Properties:

Excellent water resistance, NG & EGDN pulled out by gravity, NG headache, expensive, easy to initiate, detonator sensitive, shock sensitive.

VOD: 8,000 to 22,000 ft/sec.

Packaging:

(a). Diameter - 7/8" to 3 ½"

(b). Length - 6" to 20"

(c). Weight - 2 to 6 pounds

(d). Packaging Materials:

Spiral Wound Paper Tubes

Spiral Wound Manila Paper Shells

c. Ammonium Nitrate

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J. R. Glauber first synthesized ammonium nitrate in 1659 by combining nitric acid and ammonium carbonate. Ammonium nitrate, which Glauber named "Nitrum Flammans", occurs in nature only rarely and then in very small amounts. Today this chemical compound has two widely recognized and diverese uses:

An important fertilizer for the agricultural industry

The basic ingredient of most commercial explosives, where it serves as an oxidizer.

In 1867, two Swedish chemists, C. J. Ohlsson and J. H Norrbin, patented an explosive, called ammoniakrut, which consisted of ammonium nitrate either alone or in mixture with charcoal, sawdust, naphthalene, picric acid, nitroglycerin, or nitrobenzene. Theoretical calculations had shown that large quantities of heat and gas were given off by the explosions of these mixtures. The proportions of the materials were selected in such a manner that all of the carbon should be converted to carbon dioxide and all the hydrogen to water. Some of these explosives were difficult to ignite and to initiate, but the trouble was remedied by including some nitroglycerin in their compositions and by firing them with fulminate detonators. They were used to some extent in Sweden. Nobel purchased the invention from his fellow-countrymen early in the 1870’s, and soon afterwards took out another patent in connection with it, but still found that the hygroscopicity of the ammonium nitrate created several problems. He was not able to deal satisfactorily with the problems until after the invention of gelatin dynamite.

1935, experimentation began on blasting with a mixture of prilled fertilizer grade ammonium nitrate (FGAN) and carbon black or cold dust at a surface coal mine in Indiana. The mixture was packaged in large tubes and was primed with 20 pound charges of dynamite. It is popularly believed that this product was developed because of publicity about the 1947 Texas City disaster in which two ships laden with ammonium nitrate fertilizer blew up. In actuality, that explosion occurred with grained AN, not prilled, and in 1947 the time was not correct for a new blasting material. The success of the Indiana experiments was that prills had become commonly available (all fertilizer production in the US having converted to prilling by 1948), and that dry drilling of large diameter blastholes in the surface mines was becoming the norm. The person responsible for the product was Bob Akre of the Maumee Collieries, and the product was called Akremite. Within a very short period of time after the May 1955 experiment other mines began using prills mixed with common #2 diesel fuel, and the name ANFO was soon applied.

Prills: Prills denote the ammonium nitrate pellets obtained by cooling free falling droplets of the molten salt in so called prill towers. By special processing, they can be porous and capable of absorbing a certain percentage of liquid hydrocarbons. Under the same name, "Prills" also the ready made ANFO – explosive marketed.

Uses: Ammonium nitrate is the most important raw material in the manufacture of industrial explosives. It serves also as constituent in rocket propellants, in the capacity of a totally gasifiable oxygen carrier.

Properties

Hygroscopic and very soluble in water.

Product shows great tendency to cake.

Marketed as dense prills and as porous prills.

Colorless crystals

d. ANFO (Ammonium Nitrate and Fuel Oil)

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Ammonium nitrate explosives are mixtures of ammonium nitrate with carbon carries such as wood meal, oils or coal and sensitizers such as nitroglycol or TNT and dintroluene. They also may contain aluminum powder to improve the strength. Such mixtures can be cap-sensitive. The non-cap-sensitive’s are classified as blasting agents.

Mixtures of porous ammonium nitrate prills with liquid hydrocarbons, loaded un-cartridged by free pouring or by means of air loaders, are extensively used under the name NAFO Blasting Agents.

Uses - Construction, Road Building, Quarrying

Ingredients: Prilled Ammonium Nitrate and Fuel Oil

Properties:

A blasting agent which requires a booster for initiation. Very hygroscopic.

Available in bulk or in bags. Requires simplistic facilities for production and easily improvised for illegal/terrorist application.

VOD: 12,000 - 15,000 ft/sec.

Packaging: Usually in 50 pound paper/plastic bags.

e. PETN (Pentaerythrite Tetranitrate)

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1901, PETN is the most stable and least reactive of the explosive nitric esters. It is also one of the most powerful and brisant explosive, with good stability.

Uses: It is used in high-efficiency detonators, detonating cords, and to produce boosters. PETN can also be incorporated into gelatinous, industrial explosives.

Properties

White to light gray in color.

May be exploded if subjected to severe shock. A shock from a carpenters hammer on a floor or other solid object may cause initiation.

Insoluble in water, sparingly soluble in alcohol, ether, and benzene, and soluble in acetone and methyl acetate.

VOD 27,200 ft/sec.

f. RDX (Clclotrimethylenetrinitramine, Cyclonite)

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The name cyclonite was given to this explosive by Clarence J. Bain because of its cyclic structure and its cyclonic nature. The Germans call it Hexogen, the Italians T4.

Today, Cyclonite is probably the most important high brisance explosive. Its brisant power is high, owning to its high density and high detonation velocity. It is relatively insensitive as compared to PETN which has similar strength.

RDX is also used as a medicine, under the name of methenamine, used for the control of urinary tract infections, also used in the manufacturer of plastics, and as an accelerator for the vulcanization of rubber.

Uses: Manufacture of boosters, detonating cord, detonators, and placed in a plastic binder.

Properties

White crystalline solid or red depending on use. If used in detonating cord it will be red to pink.

High brisance

VOD 27,394 ft/sed

g. Pentolite

Pentolite is a mixture of 50% PETN and 50% TNT.

Uses:

Manufacture of cast boosters.

VOD 24,600 ft/sec

h. Binary Explosives

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Binary or two component explosives are blasting explosives that are formed by mixing or combining two commercially manufactured, prepackaged chemical ingredients, consisting of oxidizers, flammable liquids or solids, or similar ingredients which individually are not classified as explosives but which are when mixed or combined, form a detonable mixture.

The unmixed ingredients of this type of explosive are generally not subject to the transportation requirements applicable to explosives, thus they may be transported in less than required quantities without a placard.

Generally, this type of explosive is used for intermittent or limited usage due to mixing and time requirements.

Kine-Pak and Kine-Stick are a mixture of ammonium nitrate and nitro methane.

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Uses: Booster, Rock Buster, Demolition

Ingredients: Crushed Ammonium Nitrate and Nitromethane (dyed red)

VOD: 14,000 ft/sec.

Packaging:

2 pound to 1 pound clear & colored plastic tubes & cylindrical containers

Some manufacturers may pre-mix ingredients

Manufacturers

XPLO Corporation Atlas Powder Company

i. Boosters

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The development of non-cap sensitive and insensitive explosives for civilian and military use created the need for compact high detonation pressure boosters. NG based versions of boosters were available, but were in less-than-convenient packages and did not fit the overall trend toward bore holes containing non-nitroglycerin based explosives.

During the 50’s and 60’s there was an availability of low cost military high explosives that had been released to the commercial market. The availability of these products and the need for non-NG based boosters prompted the development of the cast booster.

There are several forms of boosters available and they have varying properties and sensitivities.

Cast Boosters are cap-sensitive explosives that typically contain the high explosive trintotoluene (TNT) as the casting material. Different molecular explosives are mixed into the melted TNT and impart additional energy and/or sensitivity to the booster. Molecular explosives are energetic materials that contain all of the elements for a detonation reaction in the molecules of the explosives.

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Pentolite Boosters

A mixture of PETN and TNT.

Composition B Boosters

Boosters that contain the military explosive composition "B" (RDX), and TNT with wax added to the mixture. Many of the boosters that are generically given this name are diluted with additional amounts of TNT.

Torpex Boosters

Mixture of RDX, TNT, and aluminum.

Amatol/Sodatol Booster

Pentolite or Composition "B" boosters that contain amounts of ammonium nitrate or sodium nitrate. These are called amatol or sodatol, respectively.

Tetryl or Tetrytol

Sensitive mixtures of tetryl or tetryl and TNT.

Cast boosters can be initiated by a detonator or detonating cord.

Uses - To initiate blasting agents

Ingredients:

(1.) TNT

(2.) PETN

(3.) Binary

(4.) Pentolite (TNT & PETN)

Properties:

Used to amplify the effects of a detonator or detonating cord to a degree that it will initiate a less sensitive explosive, usually a blasting agent.

Three forms are available: Cast, pliable and binary. Normally cylindrical in shape and designed to be initiated with a detonator or detonating cord.

VOD: 16,000 - 24,000 ft/sec.

Packaging:

(1.) Diameter - 2" to 5"

(2.) Length - 1 2" to over 5"

(3.) Weight - 1 oz. to 2 pounds

Packaging Materials:

Heavy paper tubes of various colors

Plastic tubes of various colors

Slip on boosters, which are pliable, require no packaging

Metal tube

j. Detonating Cord

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Detonating cords, all detonate, with the primary use is as a link.

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In nonelectric blasting, detonating cord was developed after safety fuse. A variety of detonating cord had a military application in Europe in the 1870’s. A civilian application introduced in 1902 when Cordeau, in Europe, introduced a tin tube filled with picric acid as an initiation system for mining. A different type of Cordeau, with a lead tube and TNT, was introduced in the US in 1913. Today’s detonating cord, PETN in a fabric braid was introduced in 1938.

In electric blasting, the first cords were virtually instantaneous (detonation rate of the cord and the length provided the delay); delay connectors were introduced in the 1950’s. Additional delays were developed subsequently.

a. Uses - To link multiple shots, initiate boosters and shock tube, and demolition.

    Det Cord Video

b. Ingredients:

To identify the type of explosive that is used, look at the cross section.

(1.) PETN - White in color

(2.) RDX - Dyed pink

(3.) HMX - Dyed pink in color

c. Properties:

Detonating cord is strong, flexible "cord " with a high explosive core. The strength (explosive force) is determined by the type/quantity of explosive contained in the core load which is measured in grains per foot (gn/ft). The core load ranges from 4 gn/ft to 400 gn/ft in well over 100 different brands/types. Initiated with a detonator, other detonating cord or main charge explosives.

To positively identify if in fact you have detonating cord or safety fuse, look at the cross section. If it is white or pink, then it is detonating cord. If it is black or gray, then it is safety fuse.

d. VOD: 22,000 - 27,000 ft/sec. or about 4 miles/sec.

e. Construction:

Detonating cord is constructed with various types/quantities and colors of natural and man made fibers and plastic. It can usually be identified as to its manufacturer, brand and core load from the colors and manufacturing characteristics observed on the exterior of each length of cord. However, with the use of colored plastics as the final covering, some detonating cords can be improperly identified.

C. Military Explosives

1. TNT Demolition Blocks

TNT, was first prepared by Wilbrand in 1863 and on an industrial scale in Germany in 1891. Beginning in 1901 Germany started to manufacture TNT on a commercial scale, and in about 1902 the German Army adopted it as standard filling for shells. Other countries slowly followed the German example.

TNT’s stability, which permits melt-pour loading into munitions, stability in storage under all temperature conditions, and use in other explosive mixtures has made it the most widely used military explosive.

Uses: Used in all types of military ammunition including aircraft bombs, artillery projectiles, mines, grenades, etc.

Properties:

a. Light Yellow in color also to light gray.

b. It is one of the least sensitive explosives and in the form of demolition blocks, it is virtually bullet safe.

c. Not affected by moisture or sea water.

d. When the flame of a match is applied, TNT will burn. It will not normally detonate unless very large quantities are burned in one pile and at one time.

VOD: 22,637 ft/sec.

Packaging:

a. ¼, ½, and 1 pound blocks.

b. ¼ pound block is cylindrical, within a cardboard tube with metal ends, OD Green with a single yellow stripe in the middle of the container.

c. ½ pound and 1 pound is rectangular, cardboard wrapped with metal ends, OD Green.

d. Containers come with a predrilled cap well.

2. Composition C4

During World War II, the British used a plastic demolition explosive that could be shaped by hand and had great shattering power. As standardized by the US, it was designated as composition C and contained 88.3 percent RDX and 11.7 of a nonexplosive oily plasticizer.

Composition C was replaced by C-2, which contained 80 percent RDX and 20 percent explosive plasticizer. This explosive plasticizer was composed of mononitrotoluene.

C-2 was replaced by C-3, which contains 77% (+/- 2%) RDX and 23% (+/- 2%) explosive plasticizer.

C-3 has been replaced by C-4 because of its hardening, volatility, and its hygroscopicity. C-4 contains, RDX, Polyisobutylene, Motor Oil, and Di (2-ethylhexyl) sebacate.

Uses: M5A1 Block Demolition Charge as well as other charges (see below)

Properties: Non-odorous white to light brown, putty-like material.

VOD: 26,377 ft/sec.

3. M112 Demolition Block

Block demolition charge M112 is plastic explosive. This charge is ideally suited for cutting charges, as the adhesive backing allows the charge to be attached to any relatively flat, dry surface above freezing (32 degrees F.) The explosive may also be cut and/or removed from the mylar wrapper and hand formed as desired to suit the target.

Uses: Cutting charge.

Explosive: Composition C4

Packaging

Gray or OD with yellow markings

1 ¼ pound block

Mylar film used for covering.

Adhesive backing

4. Sheet Explosive

Detasheet (DuPont) is a flexible high explosive developed by DuPont. Sheet explosives have both military and commercial applications. It is composed of integral mixture of PETN and a binder. This explosive is flexible over a wide range of temperatures It is waterproof and available in a variety of extruded shapes and in sheets and cords.

Detasheet

Detasheet "A", the commercial form is 85% PETN is red and detonator sensitive.

Flex-X

Flex-X, (Detasheet "B") is the military variety and is colored OD green for identification and contains 63% PETN. However, it should be noted that some manufacturers will use RDX as the explosive material.

Use:

Sheet explosives are designed for use as a cutting, breaching, or cratering charge, and especially for use against steel targets. The sheets of explosives may be quickly applied to irregular and curved surfaces, and are easily cut to any desired dimension.

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