This Weeks Ceramics

Well since having both moulds made this weeks session was spent casting. I am loving the fact that I can now just keep churning out more and more ceramics from my moulds, it feels such a relief after the struggle of making the moulds in the first place.
I seem to have overcome my initial problem with my second mould. The one I cast from it last week was a bit of a flop... literally; the sides got warped by me trying to get the damn thing off the hump of the mould. To rectify this I have decided to use talc as a release agent, therefore before I cast from my second mould I lightly brush on some talc to the inner part. However I found this wasn't quite enough. 
The best way I have now found to get it off, along with the talc, is to use a slight bit of compressed air, very gently, once I have removed the other mould sections. This process needs two people, one to ease the piece upwards while one uses the air to help it release. Although not an ideal way to remove it (as me holding it could distort the shape), this methods seems to be working, although I need to be very careful in the release not to totally squash the piece.


Anyway enough of that, on Thursday I had quite a productive little day, I managed to get a successful piece out of mould 2 (after figuring the above out) and get quite a few bits and bobs done, including a tutorial with Jane about glazing. As you can see below, this is the shape of the second piece of my interlocking form brief. 

This has a hollow inside that the fist shape perfectly fits into. I'm really happy with how this has turned out and the fluid like quality of the casts and shapes I have created. I am starting to get some ideas of glazing possibilities (and will put up some sketchbook pages soon). 

On Thursday I also managed to make some test tiles for testing various glazes on. To ensure the test tiles show me how the glaze will look on these slip cast pieces, I used casting slip and poured little amounts onto a flat plaster bat. This means both the material (semi-porcelain casting slip) and the surface quality (smooth) are the same as my casts.

I love this swirled effect on the surface due to drizzling the slip on, however this unfortunately is lost in firing as the whole thing turns white. This has though given me a couple of ideas. One is to use two different coloured slips and drizzle the independently to give a marbled effect. The other is to do this with glazes, however this could be quite hard to accomplish due to the rapid drying time of glazes. I think I am going to do some tests with dyed slips to see if I can get some nice effects onto a plaster bat. 

I managed to get into the casting studio today too (Friday) and get two more of my base unit done. I also managed to get another three of the inner piece made. I decided to shorten the casting times today. This meant that the base unit it would cast thinner and the two walls wouldn't meet at various points, pulling them together and distorting the sides.

Because of making the clay walls thinner, this meant that the hollow was now bigger than the wall thickness. This meant I needed to put a little pin hole in the bottom of each piece to ensure it doesn't explode in the kiln. I also decreased the casting time on the inner pieces, making them look thinner and more refined. This did mean that I had to be extra careful taking them out to make sure they didn't distort. 

Overall another productive day. meaning I now have about 12 inner pieces and 4 base pieces.

Next week I am going to have a go at making some porcelain slip and casting some thin porcelain versions. I think this will look good as the light will be able to penetrate the thin walls of the ceramic, adding a different element to the work.

Even more Slip Casting

Happy New Year everyone =]
I'm sorry that I've not posted for about a month but here we go, quite a big post today to make up for it...
I just managed to finish my second mould at the end of last term. After a session on glazes and how to make/apply them on our first ceramics session of this year, I went into the slip casting workshop and started to produce some casts from both of my moulds. 

This is my second mould. As you can see this is a three part mould that has a spare. The spare is the bottom of the object however the entire thing is cast upside down. This was the hardest mould to make and I feel the fact that it has a part that will be inside what I'm casting means it could be a little tricky to get the mould off. 

This picture is of my first mould filled with slip. The slip we use is a semi-porcelain earthenware slip which has an agent called 'deflocculant' in it. This helps to keep the clay particles in the slip mixture suspended so they don't separate and settle (basically keeping the mixture runny). 

This is a drop out mould and therefore has no spare/plug. All I need to do is simply fill up the mould with slip, leave it for 25 minutes and pour the excess away. The idea is that the plaster (being very porous) draws the water out of the slip, drying the clay in contact with the plaster mould wall. 

This is how it looks when the top part of the drop out mould is removed and the excess clay cut off. To give a good edge at the top you cut the excess off carefully in one direction then sponge back carefully in the other direction. To then get this still slightly plastic piece of clay out of the mould I turn the mould upside down on a wooden board and let gravity pull it out. This means that I do not touch the clay itself, therefore not distorting the shape...

These above are two fired pieces from the first model. To get to this stage I let the clay out of the moulds dry until it is bone dry and then use a process called fettling (basically scraping and sponging) to remove any imperfections. It's easier to smooth the piece off at the bone dry stage as you can hold it without distorting the shape and leaving big finger marks all over it. 

I love this process because once the mould is made you can reproduce the finished piece as many times as you want. Now all I need to do is start thinking about how I want to glaze these pieces. I'm thinking of contrasts so that the two interlocking parts play off each other.