Enamelling

In a similar way to how glaze powder is fused into glass on ceramic, enamel powders are fused onto copper. The temperature however is a lot lower, any higher than 800C and the enamel starts to discolour, as I soon found out.
Before and after shaping the copper needs annealing and then plunging in cold water to cool. Gum arabic is painted onto the back of the shape after cleaning, then backing enamel is dusted on top and the copper placed in a small kiln. When opened the kiln temperature plunges and you have to keep an eye on it as it gradually climbs back up to 799C. On the opposite surface different coloured enamels are fused on in separate firings, although the process is a bit more difficult than I expected. The colours don’t behave as planned, burning out before the kiln reaches optimum temperature or leaving speckled textures (which can look nice – a bit like a dusting of snow).
I’d like to know if these copper enamels can be used on top of bisqued or glazed clay. Alternatively, perhaps panels of enamelled copper (maybe a maker’s mark) could be inlaid into the clay after firing by being stuck on, although I’d have to contest with shrinkage.

 

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Week 2 Field: Colour

This second week field project was an introduction to colour theory and the screen-printing process, and for myself an induction into the printmaking workshop.

We started with a colour mixing task. Each person in our group of six was given one of six primary colours in acrylic paint – phthalo blue or ultramarine, cadmium yellow or lemon yellow, cadmium red or magenta then we mixed the exact complimentary of this colour. So for lemon yellow which is towards the bluer end of the spectrum we would make a purple that was more red/pink. Next we mixed the complimentary colours together to get a third shade, and to get a black mixed all three primary colours into one.

SCREEN-PRINTING
Before beginning the screens needed to be cleaned with a water jet set on high and the aid of a cleaning agent. These were then left to dry by the radiator in the darkroom. Once dry a thin layer of emulsion was scraped up to form a rectangle in the centre of the screen using a trough and was left to dry for 45 minutes.

During this waiting time we cut shapes and patterns from black sheets of paper ready to expose the emulsion in the vacuum screen printing press. The cut out shapes were arranged on top of the glass box and the emulsion covered screen was put face-down on top, with a small tube placed inside to aid the vacuum. The screen is exposed to light for 2 minutes during which time the UV light burns away any unwanted emulsion to leave the stencilled shapes. Afterwards we used masking tape to tape around the edges of the screens, leaving a rectangle the size of the paper we were to print on in the middle.

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Our acrylic colours were mixed with the same volume of printing medium and the screens attached to frames over vacuum printing beds. A taped down piece of acetate helped to gauge where to place the paper and then paint was pulled firmly through the screen using rubber squeegees held at an angle. Once we’d ran out of a colour the tape was removed and screen was washed again with the water jet (on a low setting to preserve the emulsion). We layered patterns from the two screens we’d exposed to create prints like the ones below on coloured paper…

The next step was to transform these 2D prints into 3D sculpture. We were shown a Powerpoint about how artists in the past have used colour theory and were particularly drawn to Victor Vasarely’s geometric op art forms. Our final piece is made of 8 separate components which can be seen below, together forming a space-ship shaped mobile. The placing of squares of colour on top of one another was inspired by German artist Josef Albers’s ‘Homage to the Square’ series.

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The process of screen-printing feels quite laborious but once the emulsion has been exposed the screen can be re-used thousands of times. It’s also quite a fast printing process once you get going. I struggled with the technique of pulling down the paint and my first results were very uneven but I found moving to a lower table helped. There’s scope for me to experiment with screen printing slips or glazes onto acetate which can then be transferred onto rounded forms and clay vessels. Slabs could be printed onto in the same way we printed onto paper, then cut up and re-assembled. We used coloured paper and I could even add pigment to the clay itself in the same way to see if this changes the printed surface colours.

Hot melt rubber molds

I took part in my first ‘open house’ workshop today where I learnt how to use the hot melt vinyl compound Vinamold/Gelflex to make flexible moulds. Much cheaper than silicone, it can be used to cast all sorts, from plaster to wax, resins and ceramic material.However it does have some drawbacks, namely that it shrinks over time and when used with plaster or wood they have to be soaked first in water.

The Vinamold is first cut into sugar-cube sized chunks which is a bit of a challenge but is easiest done with a stanley knife and scissors. The texture is similar to that of tough meat. Next it’s heated in the microwave to around 150C which took around 6 minutes for  a full Pyrex measuring jug, a little longer for larger quantities. It’s best to check the consistency every 3 minutes or so in case it begins to burn. The objects we wanted to make moulds of were placed onto sheets of clay with a cottle to give a gap of about two fingers width in between. When the compound was of a runny, soupy consistency it was poured into the moulds and left to set for about an hour. It was easy to release the objects from inside and every tiny detail is captured. The process is so much quicker than making a plaster mould.

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