Gold
, as a cast piece, is made from a process called vacuum casting, in which the hot metal, in a molten state, is poured into a mold then the pressure in the mold is reduced to about 2.0 atmospheres or so. This helps the metal reach into all corners, giving you the desirable perfect shape like that of the mold.
Experiences from learned craftsmen states, melting old gold to make new ornaments is not an advisable practice of jewelry making.
The reasons for doing so are:
1)
Karat gold
alloys are made with a predefined usage in mind. Jewelers and craftsmen of gold alloys pay a huge amount of money to the metallurgists to engineer their alloys for the right color and use.
While the percentage of gold remains the same, as per the current standards 14K gold is always 58.5 per cent gold and 41.5 per cent of alloy metals can be very different depending on its usage. Karat gold used for casting has zinc and sometimes silicon, added to improve the flow traits, while gold alloys used for rolling and stamping are designed for strength and workability.
2) The color of the karat gold depends on the alloy metals added. In 14K white gold, nickel is added to bleach out the yellow color of the gold, while yellow and red gold is alloyed mostly with copper and silver. The 14K rose casting gold we used for this ring contains about 25 per cent copper, hence the reddish color.
Additionally, solder joints, repairs and the uses of the gold object over the years introduce impurities into ornaments.
3) The process of casting changes the gold alloy a little bit. The zinc in the alloy starts to boil off as vapor when the gold is melted– thus, the karat of the cast gold increases. Thus, we always add at least 50 per cent new gold alloy to all of our gold castings to compensate for this imbalance.
Further, it clarifies that the gold alloy in the old jewelry might not withstand over the time. Melting pieces of old gold together and/or not adding newly refined gold creates an alloy that is unpredictable and pretty unstable.
Manufacturers further claim that making jewelry from old gold does not guarantee the quality of the product.
- Is it recommended to melt down
gold jewellery
?Typically speaking, you should not melt down your gold jewellery. It is so because when you re-melt gold, you require to add at least 50% new metal or you will see pits in the resulting casting. - How do jewellers melt gold?Gold and related jewellery that begins as a cast piece are processed using the vacuum casting. In this process, hot metal or gold, in this case, is poured in a molten state into the mold. Post-this, the pressure in the mold is lessened to approximately 2.0 atmospheres or so.
- Does melting the gold purify it?Yes. In fact, melting is the oldest method to purify gold with fire. However, since the melting temperature of gold is 1064 degrees centigrade, melting at this point leads to high risks of severe burns.
- What chemicals are utilized to melt gold?To melt gold, generally, an acid mixture aqua regia or royal water is used. This chemical dissolves gold and is used to purify scrap containing gold.
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