Contact Us

For All Your Drilling & Blasting Needs

PO Box 125 • Bowmansville, PA 17507

(717) 484-4471 • (717) 733-0187
Fax: (717) 484-0410


Anfo A mixture composed of 94% ammonium nitrate and 6% fuel oil, by weight. Used as a blasting agent.
Arcing Malfunction of an electric blasting cap caused by excessive electrical amperage or current.
Back Break Rock broken beyond the limits of the rear row of holes in a blast pattern.
Bench The horizontal ledge in an excavation or mining operation along which holes are drilled vertically.
Binary Explosive An explosive prepared by mixing 2 non-explosive materials which when combined form a cap-sensitive explosive.
Blast The action of breaking and displacing rock by means of explosives. SHOT also means blast.
Blasting Agent A material or mixture consisting of a fuel and oxidizer used for blasting, but not classified as a high explosive, in which none of the ingredients are classified as an explosive. The finished product is not cap-sensitive.
Blasting Cap
(See Detonators)
A metallic tube closed at one end, containing a charge of one or more detonating compounds, and designed to initiate detonation.
Blast Hole A hole drilled in rock or other material for the placement of explosives.
Blasting Machine A battery-activated device designed for the purpose of energizing electric blasting caps.
Blockhole A hole drilled in rock or other material for the placement of explosives.
Booster An explosive chemical compound used for priming or intensifying an explosion.
Bridging Where the continuity of a column of explosives in a borehole is broken, either by improper explosive placement, or where some foreign matter has separated the charge in the hole.
Burden The distance in feet from an explosive charge, in the direction of relief, to the nearest free or open face.
Collar The top of a borehole.
Capacitor-Discharge A type of electric direct current blasting machine which uses batteries to activate a series of capacitors, whose stored energy is released to energize a blasting circuit.
Connector A device used as a delay in a non-electric circuit, connecting one hole in the circuit with another, or one row of holes to other rows of holes.
Cushion Blasting & Explosives Inspector The technique of firing a single row of holes along a neat excavation line to shear the web between the closely drilled holes.
Cutoff A portion of a blast which fails to detonate.
Deck A portion of a borehole loaded with explosives that is separated from other charges in the same borehole by inert material.
Delay Interval The time in milliseconds between successively detonated charges.
Density The weight or mass per unit volume of a material (i.e. grams/cc, lb./cu. ft.). The density of explosive materials may be measured in terms of specific gravity.
Detonation An explosive reaction that consists of the propagation of a shock wave through the explosive accompanied by a chemical reaction that furnishes energy to sustain the shock propagation in a stable manner, with gaseous formation and pressure expansion following shortly thereafter.
Detonating Cord A flexible cord containing a center core of a high explosive which, when detonated, will have sufficient strength to detonate cap-sensitive explosives with which it is in contact.
Detonation Velocity The rate at which the detonation wave travels through a column of explosives.
Detonators Blasting caps, electric blasting caps, delay electric blasting caps, and non-electric delay blasting caps.
Downline A length of detonating cord extending from the surface into the borehole and attached to or in contact with explosives in the borehole.
Duplex Wire Two separate insulated electric conductors enclosed in a single sleeve.
Electric Blasting Cap A blasting cap designed for and capable of detonation by means of an electric current.
Electric Blasting Circuitry

A. Bus Wire – Solid wire, used in parallel or series-in-parallel circuits, to which the legwires of electric blasting caps are connected.
B. Connecting Wire – An insulated solid wire connecting electric blasting cap leg wires to the blasting line.
C. Blasting Line – An insulated solid core duplex wire used between the blasting machine and the electric blasting cap circuit.

Extraneous Electricity Any undesirable electric energy, (i.e., stray current, static electricity, lightning, current induced by radio frequency energy or high voltage power lines).
Fragmentation The extent to which rock is broken by blasting.
Free Face The surface which is uncovered to provide room for expansion and movement when detonation occurs.
Fume Characteristic Measure of the amount of toxic gases produced by detonation of an explosive. The U. S. Bureau of Mines fume classes are based on the cubic feet of poisonous gases produced by a 1 ¼" x 8" cartridge.
Fumes The toxic oxides of nitrogen produced by a detonation.
Fuse Lighters Special devices for the purpose of igniting safety fuse.
Galvanometer An electrical instrument designed expressly for the purpose of measuring resistance and monitoring continuity of an electrical blasting circuit.
Ground Vibration A wave transmitted through the ground that causes the surface particles of ground to oscillate as it passes.
Hang Fire The partial burning of a charge that may eventually result in an explosion.
Ignitacord Thin wire-bound fuse with one foot markings. Its core burns with a very hot external flame at a rate of eight to twenty seconds per foot.
Initiation The act of starting the detonation of explosive material.
Lift Shot A blast which is confined on all sides and has no free face to provide relief.
Loading Factor Weight of explosive per foot in a borehole.
Mat Used to cover a blast to hold down ejected debris usually made of woven wire cable or rope.
Millisecond 1/1000th of a second
Misfire A charge, or part of a charge, which has failed to fire as planned. All misfires are to be considered extremely dangerous until the cause of the misfire has been determined.
Magazine Any building or structure, used for the storage of explosive materials.
Mud-Capping (sometimes know as "bulldozing," "adobe blasting", or "dobying"). The breaking of bounders by placing a quantity of explosives against a rock or boulder without confining the explosives in a drill hole.
Multiple Priming Two or more cartridges containing initiating devices, placed in the same borehole.
Overburden The material to be shot overlying the materials being mined, (e.g., shale overlying limestone, or sandstone overlying coal).
Pattern An arrangement of boreholes laid out in a blast area, expressed in terms of burden and spacing measured in feet.
Permissible Explosives approved by the U. S. Bureau of Mines for use in gassy underground mines. Determining factors are the volume, temperature, and duration of flames produced during detonation.
Powder A generic term describing any explosive.
Powder Column A continuous length of explosives loaded into a borehole.
Powder Factor The ratio of weight of explosive to tons or cubic yards of material blasted.
Pre-Blasting Survey An inspection and documentation of the condition of a structure prior to blasting.
Pre-Splitting Stress relief involving a single row of holes drilled along a neat excavation line, where detonation of explosives in the holes causes shearing of the web or rock between the holes. Pre-split holes may be fired in advance of production holes.
Prill Small porous pellet or bead of ammonium nitrate.
Primary Blasting The blasting operation by which the original rock formation is dislodged from its natural locations.
Primer A cartridge or container of high explosives into which a detonator is properly inserted or detonating cord if properly attached.
Propagation The detonation of a charge by shock or pressure from an adjacent explosion.
Quarry Cord Burns with an external flame at a rate of one and one-half feet per second, and is used for firing multiple charges simultaneously.
Round A group or set of blast holes constituting a complete cut or shot.
Safety Fuse A flexible cord containing an internal burning medium by which fire is conveyed at a continuous and uniform rate for the purpose of firing a blasting cap.
Scaled Distance The ratio calculated by dividing the actual distance in feet, from the blast site to the nearest structure, by the square root of the maximum weight of an explosive charge per millisecond delay period.
Secondary Blasting The reduction of over size material by the use of explosives to a size required for handling. May be accomplished by mudcapping and blockholing.
Seismograph An instrument that measures and may furnish a permanent record of earthborne vibrations and air overpressure induced by blasting.
Sensitiveness A measure of the propagating ability of explosives.
Sensitivity A measure of the ease with which an explosive can be initiated. Various types of sensitivity are expressed as: cap sensitivity, impact sensitivity, bullet sensitivity.
Sequential Blasting Machine A machine for supplying electrical energy to separate series of circuits at precise time intervals. Use of the delays between circuits within the machine enables an increase in the number of delay intervals available.
Shunt A piece of metal connecting the stripped ends of electric cap legwires to prevent stray currents from causing accidental detonation of the cap. The act of deliberately shorting any portion of an electrical blasting circuit.
Simplex Wire Single electrical conductor enclosed in an insulating sleeve.
Slurry or Water Gel Explosive materials containing substantial amounts of water and high proportions of ammonium nitrate, some of which is in water solution. May be a high explosive or a blasting agent depending on sensitizing materials used. May be loaded in bulk or tube type cartridges.
Spacing Distance in feet between boreholes in a row measured perpendicular to the burden and parallel to the free face.
Specific Gravity The ratio of the density of a material to the density of water, (e.g., specific gravity of free-flowing ANFO is approximately equal to 0.85). Specific gravities less than 1.0 are lighter than water; specific gravities greater than 1.0 are heavier than water.
Spring May be referred to as CHAMBERING. The creation of a pocket in the bottom of a drill hole by detonating an unconfined quantity of explosives in order that larger quantities of explosives may be loaded after the hole has cooled.
Stemming An inert material used to confine or separate explosives in a borehole.
Strength The measure of the energy content of an explosive in relation to nitroglycerine dynamite.
Sub-Drill To drill boreholes below the planned grade lines or below quarry floor level.
Tamping The process of packing stemming or explosive in a blasthole.
Toe Distance between the borehole and the vertical free face at the base of a bench.
Trunkline A length of detonating cord on the surface connecting downlines extending into each borehole.
Water Resistance The ability of an explosive to resist deterioration or loss of efficiency when exposed to water in a borehole.
J. Roy's Inc.
PO Box 125, Bowmansville, PA 17507
(717) 484-4471 | Fax (717) 484-0410
Email: jroys@dejazzd.com