Lost Wax: Casting to Create

Here's a very brief overview of some of the steps involved in the lost wax casting process. The Applied Arts course at North Wales School of Art & Design is really hands on with teaching and practising important processes like this. Their focus is "on the high quality craft skills needed to be a professional maker".

Spruing-up with thin rods of wax makes a tree like structure which will allows the molten metal to flow into and fill the cavities.

Spruing-up with thin rods of wax makes a tree like structure which will allows the molten metal to flow into and fill the cavities.

"Spruing Up"

Taking your organic found objects or wax shapes you have made, you have to connect them to a wax tree with little wax branches called "Sprues" all pointing "Up" so that when turned upside down the metal flows down into the spaces left after the wax melts. You want the sprues to be as thin and delicate as possible when working on small scale castings as they will also be "transformed" into solid metal and you will have to cut them off where they are attached and clean up your castings. This makes "spruing up" quite fiddly and takes longer than you think! You need a steady hand and plenty of concentration when melting and applying the wax sprues.

When your tree is finished and all the parts are secure it is fitted inside a flask. Next is a crazy process which is all about precision and timing!

Plaster

You have to mix up a bucket of special investment plaster, carefully weighing up the quantities, making sure everything is clean and uncontaminated. The plaster starts to harden very quickly so processes need to be followed really carefully and quickly, so just like a TV chef you need to know the "recipe" inside out and have all of your things weighed out and everything to hand. However, instead of putting your "mixture" in the shiny oven in your glamorous chef's kitchen, the flask of plaster goes into a vacuum chamber to get rid of the air and ensures crisply defined castings. After the specified time in the vacuum, the flask goes into the kiln overnight. This will burn away the wax and organic materials leaving the cavity to then fill with molten metal.

Casting Day

Now you can prepare your casting metals. These have to be weighed out depending on the weight of the flask and how big the castings are going to be. Accurate measurements are really important. If too little metal is melted then when it's poured in, it won't fill out the cavities, meaning your one-off castings will be sad and empty or partially missing spoiling your hard work from the previous day! 

Casting grains of silver go into the crucible to melt ready to pour into the mould. 

Lovely brass for brass castings.

Brass scrap in the crucible

You can see the chopped up "sprue-trees" leftover from a previous casting to be melted and reused in this casting.

Working with hot metal is dangerous, so safety equipment and the right tools are needed to protect yourself and those around. And maybe a nice cold drink for afterwards, as it does get VERY hot! 

When ready (again, timing is everything so follow instructions and have accurate timers), the flask is plunged into a bucket of water. This causes the special plaster to fizz and bubble dramatically like a volcanic geyser so it's very exciting!

This reaction means that the plaster should dissolve and break away leaving the metal casting to be cleaned up.

It's like excavating your own fossils!

 Silver casting of wax rings by my sister Julie Mellor.

Brass casting of plant stems collected by my sister Rozanne Mellor.

Now the castings can be sawn-off by hand, cleaned up and transformed into whatever you have planned for them! I hope this shows what an exciting and involved process casting is! For more information on the facilities, Open Days and courses at North Wales School of Art & Design at Glyndwr University check out their website or message them on Twitter@NWSADAppliedArt 

Shivering Mountain

Last Thursday I went on a field trip to Castleton with Manchester Museum. The purpose of the outdoor adventure was to try out a new app which would give geology students instant access to information from experts via videos, figures and readings. I had my smart phone with me so I could see how it worked for myself. It was quite straight forward, and would be even easier if you were used to augmented reality apps although it's probably best shown on a tablet to make the most of the multi-media features.

A view of Castleton from Mam Tor

A view of Castleton from Mam Tor

Mam Tor means "Mother Mountain" possibly due to it's breast shape but also as it appeared to have "given birth" the other mini hills around it, in reality caused by landslips due to unstable layers of shale lower down. This also led to the moniker; "The Shivering Mountain".

A noble sheep

A noble sheep

One of the features was "Beneath Your Feet" showing a map of the kinds of rock making up the area around. By accessing your camera function (which does sap your phone battery so charge up!) the view in front of you appears with markers showing points of interest you could choose to click on, accessing videos, commentary and maps. This will allow instant access to localised information whilst out and about. This technology is easy to keep up to date and add to, unlike textbooks and abandoned websites. The alternative would be carrying around huge educational tomes or having to print out current figures on lots of bits of paper to faff about with (which would have been impossible on Mam Tor which was sunny but VERY WINDY). 

castleton rocks broken slab.JPG
castleton holey slab.JPG
castleton paving slabs.JPG

Beneath Your Feet: here are some of the rocky slabs that make up the steep path.

castleton stone path cross over.JPG
crack in road castleton.JPG

This old path looks quite serene and well-trodden, like a natural part of the landscape. In contrast this huge crack in the abandoned road further along our journey clearly shows the layers of tarmac of recent years in futile attempts to patch up the constant deterioration caused by the landslips aggravated by heavy lorries from the quarry.

castleton stone wall.JPG

I enjoyed getting out in the fresh air with a really nice bunch of people and the view from Mam Tor was amazing, from far and also near if you looked closely. Part of the route was interspersed with some really nice metal markers displaying it's Iron Age history as a fort.

Face of the Sun God "Lugh"

Face of the Sun God "Lugh"

Torque

Torque

Urn

Urn

castleton blue john.JPG

Here is a site featuring Blue John, a precious mineral only found in some special areas in Derbyshire. This area was originally full of sea creatures, and fossilised chrinoid specimens can be seen in the rock. Examples of chrinoids were brought along by Manchester Museum's Curator of Earth Sciences Collections, David Gelsthorpe.

Chrinoids clustered together on the left

Chrinoids clustered together on the left

Chrinoids in Castleton rock

Chrinoids in Castleton rock

The museum has many specimens from this area. It is rich with finds having been a route for animals such as bison in ancient times.  It was great to see them in the places where they could be originally found and discuss them and learn in situ. 

his trickle of oil you can see under the grass is the product of the ancient sea-life remains that would have lived here. Combined with the maternal name and visible changes and movements, it really seems as if the rocks here are alive, and I think the aim of the app will be to animate the science and information learned from them in the same way.

castleton oil ooze.JPG

 To learn more about the rocks and fossils collections of Manchester Museum (and lots of other interesting stuff), David Gelsthorpe has his own curator's blog you can check out here.  Another good blogpost on this trip can be found at MancOnlineThere's always great stuff on at the Museum, so to keep your eye out for more events like this check out their website here. If you join their mailing list too, you can be the first to know!