Glossary of Terminology

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The process of using heat to relieve stresses within a metal. At a heat usually near 2/3rds of the metals melting point recrystallization occurs, creating a more flexible alignment among the crystals.


This refers to the use of a current of electricity to affect the color of the surface of a metal. It's most common usage is in aluminum anodizing or in the coloring of reactive metals such as niobium or titanium. The term comes from the negative pole of an electrical circuitry, the anode.


A solid solution of steel in which small carbon atoms are trapped within larger iron atoms. This structure is generally unstable at room temperature. It is a phase through which steel passes on the way to becoming hard martensite or soft pearlite or ferrite.

Bead Blasting:

A process where small glass beads are "sprayed" under high pressure onto a surface to produce a matte finish.


A rim of metal that surrounds and secures a gemstone.


The action of an acid when etching.

Black lip pearl:

The rarest, and probably most expensive of all the pearls (see Materials section).

Blind Hole:

A hole that does not pass right through a component.

Blood Groove:

See Fuller.


The process of applying heat and / or chemicals to metal in order to achieve a color oxidation.


Part of the handle, the metal material in back of and/or in front of the scales.


An alloy of copper and zinc.


The joining of metals with solder at a high temperature. The term is most often used to refer to the use of brass as a solder for steel.


To polish to a highly reflective shine.

"C" Scale:

This refers to the dial of a Rockwell testing machine on which is indicated the degree of penetration of a diamond point under a specific load.


The mineral that transforms iron into steel. High-carbon steel results when .5 percent or more carbon is present. Only a bare .8+ can be absorbed by the iron, the balance in extremely high carbon steel goes to add hardness.

Carbon Fiber:

A lightweight, very wear resistant material made of small, hair-sized graphite fibers, that have been woven together and fused in an epoxy resin with a three-dimensional appearance.


A method for surface hardening wrought iron by packing it in charcoal or other organic material and heating it for hours above 900*c.

Cast Iron:

An alloy containing between 2% and 4.5% carbon. It is hard and brittle.


To remove an edge or corner, to bevel.


Decorative work carried out with chasing tools on metallic or other hard surfaces: the opposite of embossing, which uses a similar technique, but from the underside of the metal being worked, to create a decorative scheme worked in relief. Embossed surfaces are frequently chased to render the design crisp.


The cut away area in front of the guard of some knives, it may be large enough to fit a finger or a very tiny cut out area, a choil is a negative, it is an area that is not there.

Clearance Drill:

Any drill bit chosen to cut a hole of slightly greater diameter than the stud, shaft or screw that will pass through it.


A chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; a freshly exposed surface has a reddish-orange color. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.

Corrosion Resistance:

The ability of a steel to resist the formation of oxides. Steels with high corrosion resistance are commonly called "stainless".


A parallel-sided depression machined into the mouth of a hole, for instance to hide a screw head.


A cone-shaped depression machined into the mouth of a hole.

Critical Temperature:

The point at which carbide particles in steel begin to dissolve into their surrounding matrix, creating the phase called austenite. The temperature range in which this austenizing, takes place is called the critical range.


Referring to a specific pattern in Titanium, where the natural crystalline grain structure has been grown to a state that it is visible to the naked eye.


The name given to pattern-welded steel, a laminated structure know for its intricate patterns. (refer to the Materials section for more information).


The technique of inlaying gold or silver into grooves gouged out of a steel surface, often favored for the decoration of sword hilts. Originated with Muslim artists of the Near East and was later adapted by Northern Italian and Spanish craftsman in the fifteenth century, from which it spread into the the rest of Europe. Steel is scored and soft gold is hammered over this area- the gold stretches into the tight recesses and undercuts made by the scoring locking the gold into place.

Decalescence Point:

In heat-treating steel, the temperature at which pearlite changes into austenite.


Commonly signifies a device for forming a male thread on a shaft or rod. Otherwise, any tool used to form metal by compression.


A CAD/CAM assisted, extremely fine metal cutting process. An electrical current jumps from a wire to the work, melting a minute part of it, which is washed away by water which is also the coolant. Wire cutting is very accurate and relatively slow.


A technical process in which a matrix is suspended in a bath of free metal ions, that are then influenced to attach themselves because of the creation of a flow of electricity, generally from a rectifier.


The decoration of metal sheet by hammering it up in relief from the inside.

End Mill:

A cylindrical milling cutter with cutting faces on its end and usually on its sides as well.


The application of ornament to metal by cutting the pattern directly into the surface with special tools such as the burin and graver.

Epoxy Resin:

An adhesive consisting of two viscous constituents which, when mixed together, react to form a solid mass.


A shield or plate set into the handle to be engraved with the owners name or initials.


The decorative technique most commonly used on arms and armor. The process consists of tracing a design into the metal with an etching needle through a previously applied acid-resistant substance like varnish. The application of acid "bites" into the exposed surface, leaving a permanent pattern which can be blackened or gilded after the varnish is removed.


The lowest solidification temperature of an alloy or a metal. Also defined as the point at which metal goes most directly from liquid to a solid.

Female Thread:

A thread formed on the inside face of a hollow, cylindrical component. For example the thread on a nut.

Fence or Fencing:

The art of sword-fighting.

Ferric Chloride:

A corrosive salt substance used to etch copper and brass and often used to bring out the pattern in damascus steel. Used as a liquid and diluted with distilled water.


A relatively soft solid solution in which carbon atoms are trapped between body-centered cubic iron crystals.


Literally "of iron", a metal, the main constituent of which is iron.


Decorative patterns created by selective removal of small areas of metal with a needle file. In knife-making this usually refers to small-scale ornamentation on edges.


Refractory bricks made specifically for use in high temperature applications such as to line the inside of kilns and ovens or to solder upon.


An oxide of copper that forms within sterling and gold alloys when heated, particularly in the presence of free oxygen. It appears as a purple to black stain.

Flat Ground:

The surface of the blade is flat from, or near the spine of the blade tapering to the cutting edge bevel.


Straight or spiral grooves between the cutting faces of a tap, reamer or drill bit. The flutes provide for the clearance of removed material.


A chemical substance used to absorb oxides and prevent them from forming on metal. Used during hard soldering, melting metal for preparation in casting, and in forging. In soldering it is used to ensure that the solder flows. Any oxide present on the metal tends to prevent the solder from flowing. The flux is applied to the parts to be soldered and prevents air from reaching them. As a result, no oxide is formed, so the solder is able to flow and join the metal.


To shape and form metal while it is red-hot with blows by a press or hammer. This term also refers to the hearth on which a fire is maintained for the purpose of heating metal.


A workplace where cast components are produced as well as large-scale steel fabrication.


A style of knife construction in which the steel of the blade extends through the full shape of the handle.


A rounded or beveled groove or slot that reduces the weight of the blade of a sword or dagger without weakening it. Also the act of the creation of a fuller shape for decorative use. Many blades use fullers, even when they are so short that the physical effect is negligible, keeping them only as aesthetic features. The fuller is also called a blood groove, since it appears as if the blood runs into it when puncturing flesh.


The mounts of a weapon, usually metal. The term is most frequently used in connection with Japanese swords.


Plating with a thin layer of gold.


In metallurgy, a cluster of crystals with a common orientation. Grain size is important to knife-makers because grain size affects the strength of a metal. A large-grain structure, because it has fewer grain boundaries, is not as strong as small-grained material.


A chemical element with the symbol Au and an atomic number of 79. It has been a highly sought-after precious metal for coinage, jewelry, and other arts since the beginning of recorded history. The native metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Gold metal is dense, soft, shiny and the most malleable and ductile pure metal known. Pure gold has a bright yellow color and luster, which it maintains without oxidizing in air or water. Gold is one of the coinage metals and has served as a symbol of wealth and a store of value throughout history. Gold standards have provided a basis for monetary policies. It also has been linked to a variety of symbolisms and ideologies. Although primarily used as a store of value, gold has many modern industrial uses including dentistry and electronics. Gold has traditionally found use because of its good resistance to oxidative corrosion and excellent quality as a conductor of electricity.

Gold leaf:

Gold that has been hammered into extremely thin sheets and is often used for gilding. Gold leaf is available in a wide variety of karats and shades. 22-karat yellow gold is the most commonly used.


A cross-piece that separates the handle from the blade of a knife or sword and protects the users hand. In swords this is also called the hilt.


To cause a change in the crystal structure of steel that increases its wear resistance and toughness. This is commonly done through quenching the steel when it has reached a specific temperature, the critical temperature.


The ability of a material to resist penetration.

Heat Sink:

A material used to absorb or draw heat away. In tempering for instance, a scrap of steel could be laid across a thin section of a blade to protect it from over-heating.

High-Speed Steel:

A special alloy tool steel which retains its hardness and cutting edge at relatively high temperatures.

Hollow Ground Blade:

A blade in which the cross-section incorporates concave facets, requiring very skilled forging and grinding. It potentially offers a very sharp edge. It is done by grinding the blade on a round surface (face of a wheel) with a sanding belt on it and forming a concave hollow above the cutting edge and below the top edge of the blade. Especially effective for showing the most potential in the pattern twisted Damascus.


Small decorative material generally set flush with a surface and locked in place via undercuts and sometimes adhesives.


A unit of purity for gold alloys. Karat purity is measured as 24 times the purity by mass. Therefore, 24-Carat gold is fine (99.9% Au w/w), 18-Carat gold is 18 parts gold 6 parts another metal (forming an alloy), 12-Carat gold is 12 parts gold (12 parts another metal), and so forth.


A high temperature oven with many available uses.

Laminated Steel:

See San Mai.


The technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, appearance or other properties from the use of differing materials. A laminate is usually permanently assembled by heat, pressure, welding, or adhesives.


To arrange or draw the pieces. There is an important distinction between this and designing. Designing is a conceptual activity. Once it has been done, the pieces of the design can be laid out.

Lay-out Dye:

An alcohol-based paint used to facilitate marking on metal. This paint, often blue, is brushed onto steel where it dries quickly. A sharp point, like a scribe, will leave a bright, highly visible line when scratched through.


Thin sheets of metal between the frame and handle material.

Liver of Sulfur:

Potassium sulfide- a compound dissolved in water to create a patina on sterling and copper.

Male Thread:

A thread on the outside of a cylindrical component, for example, the thread on a bolt.


The property, usually of a metal, of being easily worked without fracturing.


A phase of hardened metal. In the case of steel it is formed by quenching the material when it is heated to the critical range. The result is a tough, brittle material that when viewed under a microscope, resembles a pile of straw.


a natural object originating in outer space that survives impact with the Earth's surface. A meteorite's size can range from small to extremely large. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids. When a meteoroid enters the atmosphere, frictional, pressure, and chemical interactions with the atmospheric gasses cause the body to heat up and emit light, thus forming a fireball, also known as a meteor or shooting/falling star. Meteorites have traditionally been divided into three broad categories: stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites are largely composed of metallic iron-nickel; and, stony-iron meteorites contain large amounts of both metallic and rocky material.


A method of removing metal in which the workpiece is brought into contact with a tool mounted on a rotating spindle.

Moh's Scale:

A system of relative hardness between substances. This scale was devised for mineral identification and uses ten minerals to demarcate points on a continuum that runs from talc (#1) to diamond (#10). Annealed steel is about 5 on the scale. Hardened steel is about 6 1/2.


A technique in which multiple layers of non-ferrous metals of contrasting color are fused together and distorted to reveal a patterned material. In most cases the resulting material can be treated like any other metal.

Needle Files:

Small files between 3 & 6 inches long. They are available in many shapes and several degrees of coarseness. Needle files are measured by their whole length, while other files are measured by the tooth section.


A decorative black inlay used to best effect on a surface of silver or gold. A compound of sulphur combined with silver, lead and a small quantity of copper. It is fixed in place by heat.


The process used to relieve stresses in steel. The material is heated to about 100 degrees above its critical temperature and allowed to cool in air. This creates an even grain pattern and a malleable steel.


The penile bone of a walrus, large enough to make knife handles out of.


The process in which oxygen combines with elements to create new compounds called oxides. These are detrimental to metal and should be avoided.


A style of knife construction in which the tang extends partway into the handle. The tang can be a narrow shaft that is enclosed in the handle or as wide as the handle.


Any of hundreds of surface films on metals to provide a desired color or surface finish.

Pattern-welded steel (Damascus):

A method of blade manufacture involving the forging and hammer welding of both iron and steel together to form a specifically patterned homogenous metal. The pattern is revealed through polishing and acid etching. (For more info please refer to the Materials section).

Pave setting:

A style of setting in which many stones are set very close together, covering the metal like miniature paving.


The relatively soft phase of annealed steel made up of ferrite and cementite.


An acid or detergent type substance used to clean flux and oxides from metal after heating- for example after soldering. Commonly used in hot liquid form.


A precious silvery-white metal, the chemical element of atomic number 78. It is one of the rarest elements in the Earth's crust, and is generally non-reactive. It exhibits a remarkable resistance to corrosion, even at high temperatures, and as such is considered a noble metal. Because only a few hundred tonnes are produced annually, it is a scarce material, and is highly valuable and is a major precious metal commodity.

Plug tap:

A tap for cutting a female thread right to the bottom of a blind hole.


Traditionally a spherical knob, often highly ornate serving as a counter-weight at the opposite end of a sword to the point. The end of the sword tang above the grip.


To plunge heated steal into a medium such as oil to cool it. The more rapid the quenching the harder the steel becomes.


The crossbar on the hilt (guard) of a sword that extends out.


A sword originally worn with civilian dress, distinguished by its long straight blade and complex guard. With the development of fencing techniques, the rapier became a fashionable thrusting weapon.

Reactive Metals:

Any of the six metals in groups 4B or 5B of the periodic table. They are characterized by light weight, low malleability, and the ability to form a consistent and durable oxide film.Titanium is the most commonly known of the reactive metals.


A tool for fine-finishing a hole to accurate dimensions and shape.


The acid-proof material used to protect metal when etching. For strong acids a common resist is asphaltum. For a weaker substance like ferric chloride, nail polish can be used as a resist.


The process by which a metal changes from a liquid to a solid state.


The usually flat area of a blade generally above and, or behind the grind of the blade.

Rockwell Test:

A test used to determine the hardness of a sample. A machine called a Rockwell Hardness Tester drops a diamond point onto a sample at a given load and measures the depth of penetration. The disadvantage of this test for knife-makers is that it measures only hardness, not toughness or wear-resistance.


A curved, single-edged cutting sword used exclusively by cavalry.

San Mai:

A three layer sandwich consisting of a very hard tool steel core, the outer sides are of softer material that gives great strength, forge-welded together. Can also be of a solid or Damascus core, with a contrasting damascus pattern on the outside.

Sanding Stick:

A simple tool consisting of abrasive sand paper wrapped around a narrow, flat board. Sanding sticks increase leverage and control when using sandpaper.


Also called a sheath. The protective outer casing for an edged weapon, particularly swords and daggers. The term scabbard is generally used for swords, and sheath for smaller blades such as knives or daggers.


The handle parts on each side of a full tang straight knife or the parts on the sides of a pocket knife or folder.


A pointed metal instrument used for making lines on work.


Using a needle or knife point to scratch or cut designs on whalebone or ivory, then applying ink; similar to the process of tattooing.


The trade name for a 3M product for a scratchy plastic material used to make scouring pads. These pads are handy for cleaning oxidized metal. They also create an attractive frosted finish.

Silicone Carbide:

A very hard man-made substance used in making coated abrasives (sandpaper).

Silver (Hard) Solder:

An alloy of more than 90% silver used to join metal at temperatures over 1300*F. This is a confusing term because there is a soft solder that contains a small amount of silver and is also called silver solder. To make matters more confusing, there is one particular alloy of silver solder called hard solder. Other popular grades of silver solder are known as easy and medium. These types of solder are used in jewelry applications and are available in gold and platinum versions as well.


Another name for scales, the flat pieces that are used for the outside handle of a knife.

Soft Solder:

Any of a number of alloys used to join metals. Soft solders have lead and/or tin as a principal ingredient, and melt between 400* & 600*F. A popular variation is made of 96% tin and 4% silver. This is a strong and bright colored solder, but it is not as strong as silver (hard) solder. Soft solder is used in plumbing and electronic applications.


The process of joining metal using an alloy called solder. The solder is designed to melt at a temperature lower than the metal it is intended to join. The work and solder are coated with flux and are heated until the solder melts. On cooling, it solidifies to form a firm joint. The terms easy, medium, and hard solder describe solders with progressively higher melting points. Thus, some joints can be made at a relatively low temperature without melting earlier joints made with a higher-melting point solder.


A metallurgical technique that uses controlled heating to convert irregularly shaped crystals in steel into ball-shaped particles.


A process where a substance is added to prevent unwanted changes in the state of another substance, which results in material that is resistant to temperature changes, humidity extremes, UV rays and saltwater, as well as many acids and solvents commonly encountered in day-in-day-out use.

Stainless Steel:

Stainless steel does not readily corrode, rust or stain with water as ordinary steel does, but despite the name it is not fully stain-proof, most notably under low oxygen, high salinity, or poor circulation environments. Stainless steel differs from carbon steel by the amount of chromium present. The only stainless that will not rust is used in sinks and hospital fittings. Any stainless that will hold an edge will be subject to humidity, salt and acid fluids. (Stainless means just that when applied to knives, it stains less.)


An alloy of wrought iron and carbon, capable of being hardened by heating and quenching (rapid cooling) in oil. This hardening process could cause embrittlement; gently re-heating (tempering) increases the metals resilience.

Sterling silver:

An alloy of silver containing 92.5% by mass of silver and 7.5% by mass of other metals, usually copper. (Fine silver is 99.9% pure and is generally too soft for producing functional objects; therefore, the silver is usually alloyed with copper to give it strength while preserving the ductility and beauty of the precious metal).


A dagger with a very slim blade intended for thrusting.

Stock Removal:

A general term for the process of shaping knives by selective grinding/filing away of material. It is an alternate method to forging, though stock removal is often used after forging as well.

Super Conductor:

Remnant copper/Titanium/Niobium conductive wire from the super-collider project, built, but later abandoned before completion by the US Government in the 90's. Made from a matrix of 47% Titanium/ 52% Niobium wires pulled thru a copper core, superconductor was (going to be) used to move electricity in the particle accelerator.


A generally short beveled grind opposite the main cutting edge, running from the tip of the blade, back.


The part of the Blade that is fastened between scales to make the handle, or goes through a hole in the handle material.


A style of construction in which a metal slab usually of contrasting metal to the blade, often titanium, (the same thickness as the blade material and its partial tang) wraps around the partial tang on three sides. The tang-wrap is connected internally via hidden screws to the blade and partial tang. The handle is then built via slab construction on both sides of the core of the tang and tang-wrap. The transition seams can be covered by inlays.


A cutting tool for forming a female thread inside a hole. Also the process of cutting threads.


To soften hard, brittle steel by heating and holding it to a specific temperature without greatly diminishing the toughness and wear resistance of steel.


Timascus consists of two or more titanium alloys laminated and patterned resembling steel damascus. The various alloys color differently through the use of heat or anodizing. Each type of titanium alloy has the potential for a new color combination.


The ability of a metal to resist breaking.

Vernier Gauge:

A precision measuring device of the caliper type.

Wear Resistance:

The ability of a metal to resist abrasion.

Wire EDM:

See EDM.


The hardening of a metal caused by hammering or bending, which often makes the metal too hard to work with until it has been softened by annealing.

Wrought Iron:

Pure iron which does not contain any carbon to turn it into steel. Wrought iron is very malleable and easily worked, but can only be hardened by "case-hardening".