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A

Annealing

The process of reheating a medal blank between two successive passes, so as to soften the medal hardened by the striking and to carry on the stamping until the design relied is fully brought up.

B

Brilliant Uncirculated (BU)

A special finish obtained on some collector's coins. They are struck with new dies and present a bright and perfect appearance, without any traces of damage as they have never been circulated

C

Casting

The procedure for reproduction in metal of the work sculpted by the artist: liquid metal is poured into a mould made from the original model.
See also: V-process casting, lost wax casting.

Collector's coins

Legal tender coins which however differ from circulation coins in terms of one or more physical characteristics (size, alloy, weight), or design or surface finish (proof or brilliant uncirculated quality).
 

D

Diameter

The diameter of a coin or medal after striking and cropping.

Direct Cutting

The technique whereby the artist carves the finished work directly from the material, without recourse to a preliminary model. Direct cutting generally uses the intaglio method, with the engraver inverting his drawing on a block of steel. This technique requires considerable technical mastery, since it is impossible to correct any mistakes.

E

Edge

The curved surface of a coin, which may be smooth, reeded, or lettered.

Electroplating / Galvanotype

A technique allowing articles made of appropriate materials to be coated with a metal deposit by electrolysis.
In medal making, the galvanic deposit should be quite thick and easily removable for it is used here to create a new model which is the exact replica of the model to be coated. The new model, called ""galvano"" (abbreviation for galvanotype), is employed on the reducing machine to carry out the engraving of the steel die.
A ""galvano"" may also be produced for decorative purposes, in which case an appropriate finish treatment is applied to the surface.

Enamelling

The process by which a vitrified substance is applied to the surface of objects made of appropriate materials. This substance can be either opaque or transparent and can be coloured by means of various metal oxides.
 

F

Fineness (Standard of)

The proportion of pure precious metal contained in an alloy. It is expressed in parts per 1000. For instance, 0.920 gold means that the alloy is made up of 920 parts of gold and 80 parts of other metals. Carat is a former standard of fineness for gold.

Florentine bronze

In reality a brass yellower in colour than bronze, containing 85% copper and 15% zinc.

G

Gold plating

The process of coating articles made of base metals or silver by electrolysis with a thin and adherent deposit of gold for decorative purposes.
 

H

Horn of plenty

The signature (symbol or mark) of the Monnaie de Paris since 1880.

Hubbing or Hobbing

The process of producing a master die by pressing, thereby imprinting the desired design from a steel block cut in relief (hub or punch).
 

I

Ingot

A piece of cast metal, usually rectangular and thick, from which strips are made.

Intrinsic value

Value of a coin determined by its fine metal content.

Issue year

Figure indicating the date of issue of a coin.
 

L

Lamination

The process of compressing un ingot into a thinner plate, using a rolling-mill with two cylinders turning in opposite directions. The adjustment of the distance between the rollers allows to obtain the desired thickness.

Legend

The inscription on a numismatic item. Refers mainly to words on the circular edge.

M

Master die

Intaglio engraved tool.

Mechanical reduction

See Reducing machine or Reducing Lathe

Mint mark

Letter or symbol indicating the mint where the coin was produced or identifying the mint-master or the engraver.

Mintage

The total number of copies of a product.

P

Patina

The finish given to a medal, coin or art bronze. A natural patina is the result of atmospheric corrosion, and is acquired over time. Patinas are applied artificially using oxidation to reduced shine and emphasize relief. For castings, they are applied hot to increase the reflective qualities and accentuate the forms.

Proof

The finest finish on a coin, followed by the Brilliant Uncirculated quality (BU) and the ordinary. A proof coin is a piece produced by a technique involving specially prepared dies and blanks and special striking, resulting in particular sharpness of detail and a virtually flawless surface. They are mirror-like over the field with frosted design.

Q

Quench

Rapid cooling after heating, thanks to which an alloy at the ambient temperature retains the mechanic properties of the structure acquired at a high temperature.
 

R

Reducing machine or Reducing Lathe

A machine which uses the same principle of geometrical equivalence as a pantograph, which moves through all its plans. At one end of the machine the intaglio model (about three times larger than the diameter of the medal or coin) is positioned and at the other end the steel block that will be engraved. A tracer moving from the centre out picks up all the reliefs of the model and transmits the information with the required reduction of scale to a cutting tool that engraves the steel.

Reverse

The opposite side of a coin or medal to the obverse.

Rim

Slightly raised boundary between the edge and the depressed field on the obverse and reverse of a coin. It protects the relief of both sides against wear. It also serves to pile up coins and facilitates their packing in rolls.

S

Screw press

The first machine used for stamping coins and medals. The lower die was fixed in place and the blank was positioned on top of it with a collar. The upper die was then screwed down with great pressure to stamp the piece. It first appeared in Germany towards the middle of the 16th century and its use became widespread in France under Louis XIV at the beginning of his reign.

Silver plating

The process of coating articles made of base metals by electrolysis with a thin and adherent deposit of silver for decorative purposes.

Striking

The process of imprinting the design cut in a die onto a coin or medal blank, using a press. The obverse and reverse are stamped simultaneously.

Strip

A narrow plate of metal out of which blanks are punched.