The art of coin design is a unique challenge. The elements of the design must be perfectly balanced to accommodate the round shape and small size of the finished coin. Two-dimensional sketches and paintings must have qualities that will translate to three dimensions on a finished coin. Drawing and painting become sculpture through the skill of our engravers.
The Ottawa Mint specializes in the production of hand-crafted medals and commemorative coins. Unlike the high-volume turnover of the Winnipeg facility, the Ottawa operation produces an average of just 8000 collector coins per eight-hour shift. Each piece is treated as an individual work of art.
How do we mint collector coins? Read on to discover the process that transforms precious metal into precious coins...
1. CONCASTING This is where the life of a numismatic coin begins. Silver is melted down into bars for the production of collector coins. The cutter chops these large bars into smaller, easier to melt pieces. The newly poured bars of silver slowly move out of the furnace and through a series of cooling boxes before proceeding to the saw, which cuts the bars into pieces approximately two feet long. Next, the planer removes a thin layer of silver in order to expose the shiny, unoxidized interior.
2. ROLLING The bar is rolled to thin it, then blanks are produced. At the Roughing Mill, bars are passed through two steel rollers. The Roughing Mill produces gold bars that are 4mm thick and silver bars that are 8mm thick.
Annealing In the annealing procedure, silver is heated in a furnace - gold bars are not heated as they are much softer and more pliable. The temperature of the annealing furnace reaches a white-hot 700 degrees Celsius in this 6 to 7 hour process. Annealed silver bars are then rolled again by the Finishing Mill.
Finishing Bars are then passed through the Finishing Mill to reduce their thickness a second time, to the desired dimensions. Skilled workers measure each bar to ensure total precision.
Blanking The Blanking Press is used to cut blanks - coins without any image - out of rolled metal sheets. These blanks are punched out with a special die the size of a coin, powered by 40 tons of pressure per square inch. The leftover material, called Scissel, is sent back to the refinery for recycling.
3. RIMMING & BURNISHING At this stage, coins are prepared for striking. There are many steps a blank must undergo before a design is committed to its surface. Each stage is necessary to ensure longevity, precision and appearance.
The Rimming Machine This process removes the rough edge left by the blanking press, and adds a raised rim prior to striking. That way, when the coin is struck, the detail from the die will transfer flawlessly. A rim can add 10 to 15 years to a coin's life.
The Burnishing Machine Blanks are cleaned or "burnished" by tumbling with stainless steel beads of various sizes that wash and polish their surface. This can take up to six hours, as the procedure is repeated several times over. Each tumbler is used for a specific alloy to prevent cross-contamination. Blanks are then spread out evenly and hand-dried with towels. This ensures that no scratching occurs and that each blank is thoroughly dried.
Degreasing After burnishing and prior to striking, the blanks go through a final inspection and cleaning. Degreasing is done using the Finsonic process: blanks are dipped in alcohol and heated water (50-60 degrees Celsius) for about 15 minutes. Imperfect coins are sent back to the concasting room and re-melted.
4. STRIKING Coins produced at the Ottawa Mint are unique works of art. The painstaking care involved in making numismatic coins represents a commitment to the highest standards of minting.
Press Room Blanks are transformed into coins in either the Automatic Press room or the Manual Press room, where images are added to both sides. Automatic presses are mainly used to strike coins made of non-precious metals (nickel, copper, etc.), but occasionally strike more precious pieces such as gold bullion and investment coins. In an Automatic Machine, the dies will strike an average of 2000-5000 hits before they are changed. Manual presses are used to strike blanks made of precious metals (gold, silver, platinum) to create collector or numismatic coins. Most proof coins are struck twice or even three times. Tool steel dies, placed inside each press, are used to imprint the desired design on the coin's surface.
5. ENGRAVING The Mint's engravers execute the meticulous designs that grace finished coins. Each design is carefully translated from paper to die, and examined for quality at each step of the way.
Design All coin designs start with an original artist's drawing. Designs are created by artists from the Mint or by noted Canadian artists. Contributions from the general public are not uncommon. All designs must be approved by the Government of Canada.
Etched to Perfection Everything from the original design is carved onto discs much larger than coins - this is done in order to retain as much detail as possible. The discs are then copied and reduced to the appropriate size.
Displays A plaster copy of the coin design is transferred onto a rubber disc, producing a positive image. It is then transferred onto an epoxy resin disc to produce a negative impression of the original design.
Die Making Dies used to strike coins are copied from the reduced original design. A Reducing Machine works like a key cutter. It copies the epoxy disc to a brass plate, following the contours of the original disc in order to engrave them at a smaller scale on the copy.
A second Reducing Machine takes the brass plate and shrinks all of the information onto a steel die called The Matrix. This process can take up to 48 hours. The Matrix is technically the "original" die, and is copied to produce the Master Punch (this process is called hobbing).
The Master Punch is then hobbed onto another blank die to produce Working Dies, which are used in presses to make coins. Proof Dies are capable of striking coins and leaving a frosted image on top of a mirror-like background.
HAND-CRAFTED PRODUCTION