Lost Wax Casting

The idea of creating something formed in a negative space formed by wax that disappears fascinated me. Metal work at the time was something I had not had much experience with, so it seemed logical to spend two days in the metal studio. 

The process had many steps and required a lot of fine detail work and careful carving. I usually work with clay, the metal world is alien to me. Clay is large and requires only hands and a few wooden tools to create something special and unique. With metal this is not always the case. It needs heating and moulding and working to submit to your desires. It is also, in the case of this process small to handle and therefore fiddly. Not my forte! But it was a challenge I was looking forward to. 

In short the process would involve carving a piece of was into our desired design, attaching it to a wax sprue, covering it all in plaster, heating overnight to lose the wax and then adding molten silver to form a final design to be file and polished into a finished piece. 

It sounded quite straightforward! How did it go?

The process started by researching some ideas for what we could make. We had a 5cm square piece of wax which was approximately 1cm deep, so whatever we created would be relatively small. It would have been easy to focus on making a ring, but it was far more challenging to come up with something not necessarily jewellery related. 

My inspiration was a barrelling wave. 

The first challenge was to carve the wax into the shape we wanted using a saw and a file.

This task alone took approximately 2 hours. 

Once the shape was completed the challenge was to attach it to the sprue! 

This involved heating a softer wax and melting it onto the carved piece in order to create a 'branch' that could then be attached to the centre 'trunk' of the sprue.It is essential to know the weight of the complete wax piece in order to be able to melt enough silver to fill the void. 

The specific weight of silver is 10.4. This means that 1.5g of wax, which was the maximum weight we could have, would produce an item of silver which weighs 16g. Our total wax weight was 18.3g, meaning we needed to melt 190.32g of silver. (18.3 x 10.4 = 190.32) 

Once all pieces had been attached to the sprue tree, plaster was mixed and poured into the circular container holding the sprue.

The sprue needed to be held at a set temperature of around 600 degrees for 3 hours. The silver could be melted during this time in the casting machine.

With the silver melted the container holding the sprue was placed in the machine and tilted for the silver to pour into the space where the wax had previously been. 

After a matter of minutes the container was removed and slowly quenched in water in order to cool the silver. Once this was done the case could be removed from the plaster and the plaster mostly washed off in the water and then steam blasted to leave a solid silver tree with our artwork attached. 

The next step was to saw each piece from the central column. The central column can be melted and reused in further lost was processes. 

The silver needed to be polished in order for it to take on a shiny finish, rather than the dull finish from the heating process. 

After a couple of hours of filing and gentle sanding the pieces could be placed in the tumbler for the process to be finished. 

The two day workshop flew by. The process was full on and at the same time really relaxing and enjoyable. To create a small silver wave in just two days filled me with pride. It has encouraged me to continue working in small metals more than I have previously as I have discovered that I enjoy the methodical approach of metals. If you prepare everything and take your time, focusing on all the small details, you can produce something to be proud of.

21 views0 comments