| Cubic zirconia (CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of different colours. It should not be confused with zircon. Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia’s has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976. Its main competitor is a synthetic gemstone and more recently a cultivated material called synthetic moissanite.
The shapes we stock: Round, Square, Octagon, Baguette, Heart, Triangle & Trillion, Marquise & Cushion.
For Feb & March we will offer a 10% discount off existing stocks of CZ!
7 - 10 March 2013 STAND A36 Hope to see you there!
Casting
Most casting workshops have their special recipe derived from years of experience to get the perfect cast, some find it a difficult challenge and an uphill battle but getting the basics right is easy.
Casting is a process of making pieces that involve the pouring of liquid metal alloy into a mould. It is usually referred to as lost-wax casting because the casting mould is created using a wax model that is melted away to leave a hollow chamber in the middle of the mould. The technique has been used for thousands of years, and is still widely used today by many to make precise reproductions of original jewellery pieces.
There are three types of casting:
- Cuttlefish & Delft - Ideal for making silver jewellery at home since it is a very quick and easy way to make some basic shapes out of silver. Or delft clay a special clay system used solely for casting. Its advantage is that it can produce a better smoother surface
- Commercial Casing - This involves making a rubber mould of the item that can be repeatedly re-used
- Lost Wax Casting - Done with a single hand carved item
Below is a quick look at lost wax casting & commercial casting:
You first need to choose which option of casting- centrifugal or Vacuum casting .You can hand carve a single item out of a special jewellers wax or if you want to do mass production make a mould of your desired item by either using an RTV silicone pourable silicone that requires little to no heat, or a rubber or silicone that is used with a vulcaniser.
Once the item has set in the desired mould with a sprue, it needs to be cut open, the moulded item can then be taken out and you are ready to inject wax, there are various injections waxes depending on flexibility and size required, the wax gets put into your wax injector, heated up and with pressure gets shot into the mould. An exact replica is made out of wax. Once you have your waxes you need to build a tree like structure on a rubber sprue base- the angle is very important here of how to sprue.
Once your tree is ready you can invest, investment is a powdery substance mixed with water to create a plaster like liquid this is poured slowly into your flask, once filled it needs to be vacuumed and debubblised to get rid of all the bubbles in your mixture, then left to set. After setting it needs to go into a burn out kiln or furnace to melt the wax away- this is called lost-wax casting.
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| Once your flask has been fired for the correct amount of time and wax burnt out you put the hot flask into the vacuum casting machine chamber or centrifugal arm, put your required metal in the crucible and melt it until molten and then pour the metal |
| into the vacuum caster or allow the centrifugal spin arm loose, this then fills your flask into the hollows. Allow the metal to cool and then quench into water causing the investment to come loose, you will then be left with your metal item that can be cut off the sprue and worked off and finished. This is in short how casting works. |
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