Collectable coins antiqued and gilded to perfection
In recent years, collectable coins featuring antiqued or gilded highlights have become particularly popular. In fact, The Perth Mint can claim some of the credit for this trend, being one of the world’s first mints to pioneer these innovations.
As a result, the coining team has unprecedented experience in the application of such finishes, using electroplating techniques to enhance selected areas of the design with a layer of 24-carat gold, or using specialised processes to add an antique finish.
Here, we explain how our coins are antiqued and gilded to perfection.
How are coins antiqued?
When it comes to antiquing silver coins it’s a detailed and time-consuming process to ensure each coin passes the final inspection and is considered coin collector ready.
The first step of the process is to place the fully designed coins upright and slightly apart in basket jigs. The basket of coins is then immersed in a tank of warm oxidising solution, which blacken the whole coin.
After only one minute, the basket is removed from the solution and the residual oxidation is rinsed off with demineralised water.
The basket of coins is then placed into a degreasing solution to further clean the coins before they are dried with compressed air.
Once dry, each coin is placed flat in holding trays, each one facing the same direction. The coin’s surface is then scoured which removes the blackened coating from the raised areas, leaving the deeper parts of the design black. When the desired finish is achieved the coins are turned over and the process repeated.
Lastly, the coins are brushed clean, lacquered and dried before they’re inspected and packaged, ready for sale.
How are coins gilded?
To gild (or selective plate) coins at The Perth Mint we use a small workstation unit which comprises of three tanks and an electrical current. The first tank is filled with a gold solution, while the other two tanks are filled with demineralised water ready for the rinsing process that follows.
Once the coins have been made and are ready to be gilded, a mask is aligned precisely over the design and face of the coin.
Each mask attached to the coin seals the areas which aren’t to be plated in gold, meaning only the exposed areas of the coin, usually the raised design, will be gilded. The opposite is true when we create reverse gilded coins.
Once the mask is aligned and clamped, the coin is lowered into the gold solution and an electrical current is passed through the coin, causing the gold solution to be attracted and attach to the coin.
The duration of this current flow determines how many microns of gold is applied to each coin.
After plating, the coin is rinsed thoroughly with demineralised water, the masks are removed, before the coin is steam cleaned and placed back on a coin tray ready for inspection.
A pioneer of 24-carat gilding in modern numismatics, The Perth Mint is noted for releases featuring this selective application on the central design motif.
The coining department’s ultimate responsibilities lie in the final inspection and primary packaging of all the Mint’s coins.
Inspection is an exhaustive process that takes nothing for granted and follows a strict set of guidelines. Even though blanks may have passed earlier testing, a sample of finished coins is fully re-tested to ensure the specifications, including weight, diameter, and thickness, are accurate.
For optimal quality assurance, a visual examination is required of all coins, and in no case is this more significant than for proof quality collectables. As our elite releases, they feature a shiny, mirror-like table (background) and delicately frosted motifs. Because these coins are presented as flawless, the tiniest imperfection results in rejection.
Having passed every testing procedure, The Perth Mint’s precious metal coins (with a few exceptions) are hand-placed in acrylic capsules providing perfect protection for a lifetime of enjoyment by our collectors.
From an innovative role in antiquing and gilding techniques to casting our world record breaking One Tonne Gold Coin, we’ve never shied away from pushing the boundaries in numismatics.
In recent years, collectable pieces featuring antiqued or gilded focal points have become particularly popular.
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