Sand casting and why I love it
In a lot of my work I use sand casting to create interesting textures and unique visual highlights.
Casting has been in use for millennia, the earliest evidence is from around 4000BCE casting gold, however the oldest surviving item known to be cast is a copper frog from 3200 BCE discovered in Mesopotamia (present-day Iraq), so casting is certainly an old and ancient technique.
Casting has been used for many tasks, not least making weapons throughout the Bronze and Iron Ages and religious artefacts throughout history. In the modern jewellery world most casting is done by using lost wax casting - this is carving a wax model, around which a mould of modified Plaster of Paris (investment) can then be formed and heated – a process which both hardens the shell and melts away the wax, leaving a cavity which is shaped exactly like the mould and can be filed with metal to produce an exact replica.
A further development occurred in 1936, when Danish engineer Thoger Gronborg Jungersen patented a method involving rubber moulds that could be reused to make multiple wax models without having to carve each one individually. This development allowed mass manufacture of jewellery to develop, allowing for repetitive, multiple castings of single pieces at lower costs, this is how most jewellery is made today.
Sand casting is very different
Traditionally a mould is made in damp sand which is heated to keep its structure and the metal is poured in, it is a destructive casting method as the mould is destroyed by the heat of the liquid metal, as such each piece is unique. In my casting I use Delft clay, a fine sandy clay (rather than sharp sand) with a mineral oil to help retain the structure of what is being cast, it was first developed by a Dutch goldsmith, Hans Karreman - this modern advancement means that less sand is used, reducing environmental impact. I adapt my Delft clay with other sands to add interesting textures.
A quick overview of the technique of sand casting (there are some great images of this process here):
I fill the bottom half of a casting flask with clay, press my former (ring, pendant, etc made in wax, wood or copper) into it
Attach the top half of the flask, will it with clay, open it to remove the former, make the necessary airholes, sprue and close it ready for casting
Once the mould is ready I melt the metal, and pour it in (see the top image), once the flask has cooled I remove the casting, clean and prepare it for use
The mould which was made for the casting is burnt during the process so is not useable again (as shown below):
So why do I love it?
It is genuine, it is not a technique that can be replicated on a mass market scale, as such it is the realm of the handmade artisan.
Every piece is unique, no two moulds are ever exactlythe same, if a piece contains sand cast elements, no-one else will have something the same.
It is seen as the “poor cousin” of casting as it does not produce an absolute copy, but this is its charm and attraction, beautiful textures and effects can be achieved with sand casting that lost wax will not achieve.
Casting is not an exact science and takes some skill and experience to be repetitively successful, however once the skill is learned it allows for creating of interesting and unique pieces such as those in my sand and fine collection
If you would like to know more about how this technique could be used in a bespoke design please contact me through the commissions page.