Monday, 8 February 2010

Clay and Porcelain Charms

Using the laser cut plaster as a mould for the clay shapes is working reasonably well. Some particles from the plaster do come off on to the clay which is not that noticeable on the white clay or the porcelain but is on the red clay. I might look into putting a coating of wood glue or varnish over the cavity so it will keep its shape longer but not compromise the surface finish.

I am thinking of using porcelain for the charms that are not the most attractive eg: mobile phones, switches. I think it will make a good contrast between this very fragile decorative material against modern mass produced products. On the porcelain I am going to put ceramics transfers of delft patterns.

Wednesday, 3 February 2010

The Competition

Charm Research

The chain is most likely to be on over night or when some is in their home by themselves.
I need to do some more research into the types of charms I am going to make. I will need to speak to numerous people about the things that they need reminded of in the mornings when they leave the house. I found an illustration in a book about charm bracelets that shows what a woman carries in her hand bag and comparing to a woman's journey through life.

Laser Cutting Plaster

The image above shows a block of plaster that I laser cut to make a cavity that could be used to make my clay charms. The plaster cut reasonably well and has been left with a rough porous surface. Since the pewter is likely the best material for making smooth surface casts, this texture could be good on the clay charms.

Most of the work on the charms I have done is for flat 2D objects so I could possibly use the porcelain for making more 3D objects.



I have started playing with different materials on the laser cutter to see which would make beautiful charms and which ones will make good initial models of making moulds.

From this investigation I have decided that the materials for the charms should be pewter as you can get great surface detail, red clay for the colour and porcelain for its delicacy and possible transfer patterns.

Depending on the detail and surface finish required I will make the initial models from MDF or acrylic. MDF will be used for pressing in to cuttle fish to make a pewter model for silicone. When the shape is more important I will used acrylic and make a silicone mould directly.

Finishing the Pewter

The pewter may come out of the mould with slight imperfections but these should be easily tidied up with filing, sanding and polishing. These models should then be ready to use to make the silicone mould. The advantage of the silicone mould is that it is more durable and can be used to make hundreds of casts before a new one is needed. You could potentially put numerous cavities in a row and even doubled up in the same mould so that you can make batches of casts at a time.

Pewter Casting

This post is going to take you through the bits and pieces I have been doing in play.

The first thing I started with was making moulds from cuttle fish. At first this was done by pressing objects into the cuttle fish and then I moved on to making shapes on the laser cutter. The cuttle fish works well for making moulds because it is relatively soft so making impressions is easy and it gives the mould a very good surface finish.

These shapes have been cut using the laser cutter. I have made a range of sizes to see which would make the best impression in the cuttle fish and to have a physical model to see the best size for the charms. From this I have decided that I want/need larger charms so that the detail is more obvious they stand out when hanging from a door but also because they make a better impression in the cuttle fish.


This image shows the two halves of a cuttle fish mould. The mould is prepared by sanding the soft side until it is flat and sits flush with it's pair. You may need to trim the edges on the band-saw so that they are the same size.

You can now make the impression. Press your shape in with your fingers, starting with the edge and work into the middle on of the model until you get it to the depth you require. Depending on the size of you cuttle fish and your model you might be able to make two impressions on the same piece. However to make sure the molten metal does not get stuck near the top of one cavity and not make it into the second you should add extra channels as shown in the picture. These can be removed easily later. Last thing to be done is to make a funnel shaped opening at the top of the mould for filtering the molten pewter in the the cavities and clamp the two pieces together.

The cuttle fish is very brittle. The image above shows the remains of cuttle fish that broke whilst pressing a model in.

Once the mould is ready and clamped together you can start to melt the pewter. It has a relatively low melting point so it can be done in a metal pot on a camping hob. It will take about 10mins to melt the pewter, and once it has you can pour it directly into the mould. It will need about 5mins to cool but it will set within a minute.

This image shows the a close up of the impression Unfortunately when removing the cast some of the mould broke off. If it had been removed cleanly the mould could have been used again by simply pressing the model in to redefine the shape of the cavity. This cuttle fish can however be used again but it will need sanded back and the impression made again.