And now for some bowls

 

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For some reason I find throwing and turning bowls more difficult than other forms. I can never seem to get the thick clay out of the base and they tend to end up with strange ridges. The pearlescent glaze here was supposed to be a gloss white but looks like it needed more than one layer.

Page 132 The Glaze Book – Gloss white 1290C

Potash feldspar                              60
Dolomite                                         20
Quartz  (flint)                                 15
China clay                                       5
Rutile                                                5

Layered on top of another glaze the opalescent effect might work but I don’t like how watered down it looks revealing the clay underneath here.

The bowl with the oatmeal glaze is my favourite – it’s got rings of different shades of orange with a subtle texture and green tinging where it’s pooled at the base. I like the detail of the running green glaze around the rim too – a touch of Lucie Rie!

Oatmeal 1290C

Potash feldspar                             45
Dolomite                                         88
Quartz    (flint)                               16
Zirconium silicate                         11
China clay                                        6
Zinc oxide                                        2
Chrome oxide                                 1

The green bowl has a pleasant mottled antique green colour – white slip with smooth satin opaque yellow green on top applied to bisque ware. I like the visible brush marks and the colour variation where the thickness is different.

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Natural glazes

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I’ve been invited to sell my work in my local hometown and want the glazes to reflect the colours of the rural landscape of North Wales. These thrown vessels have been painted with the glazes I made at the start of the year as part of the local clay project. The bowl has been pained with a glaze made from a 2:3 ratio of Potash feldspar to my clay while the rounded pot has a 2:1 mixture of Whiting and my clay. It flows very much like an ash glaze but luckily wasn’t too runny that it stuck to the kiln shelf. I’m going to add more whiting and feldspar to these glazes because the colours are much darker than I expected.

Layering slip and glaze

Here I’ve tested to see what effects can be had when layering slips and glazes onto ash white stoneware.

  1. White slip with turquoise glaze on top produces crazing in straight lines underneath a patchy shiny green.
  2. Reversing the above with the white slip on top creates a dry, textured matte surface which doesn’t flake or peel.
  3. My favourite – yellow/green glaze with blue slip painted on top forms islands of matte dark blue over a shiny surface with a very painterly effect. I like this rough, uneven texture which might look exciting on a large scale.
  4. The same as 3 but with turquoise glaze on top – this looks like a painted landscape with lots of variations of blue and hundreds of tiny bubbles encased in the surface.

I expected the slips to run off the surface when fired but the addition of glaze works to stick the raw and bisque fired clays together.

 

Stoneware mugs

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I’m really enjoying the challenge of throwing on the wheel. I feel I’ve come a long way since beginning the course in September – I can now control the clay to a degree and make the shapes I want which is new and exciting for me. Most of my last term was spent practising to throw cylinders which was a struggle because the clay is determined to flare out at the rim (hence why most teachers encourage you not to begin with making bowls).

These mugs are slightly tapered cylinders with pulled handles (attached when the body was too dry – there are cracks at the joint).

To decorate I played with layering a couple of glazes from Stephen Murfitt’s ‘The Glaze Book’ – an opaque yellow green and pale satin grey/green. At the moment I am brushing on glazes and making up small batches (100ml) but this is causing very uneven layers of colour. I might choose a couple of glazes I really like and make up a bigger batch so I can start dipping and get a more even coverage.

I don’t feel I’m very good at harmonising form and decoration. My approach has always been ‘more is more’ but I’m going to challenge myself to spend less time decorating and see if I like the pared-down results.

Week 4 Field: Pin-hole camera challenge

Our final field lab was an introduction to using the dark room and making our very own pin hole cameras. I made a pin hole camera from a shoe-box once which worked well but this time I wanted to try something new, closer to my chosen subject area. I found a few thrown unfired clay cylinders in my studio space, stuck pin-holes in their sides then cut circles of clay from a slab and squeezed them on top. Strips of gaffer tape were placed over the holes to stop unwanted light going in. The cylinders were loaded with strips of photographic paper in the dark room then I set out with one of my group members, Alaw, to try one out.
Lucky for us, the camera worked perfectly the first time. We took it outside on campus and pointed it at some undergrowth in a shaded area, exposing the paper for 4.5 minutes, which was an estimate based on our previous experience. The negative is great – it has lots of detail and a good tonal contrast.


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For some more interesting subject matter we chose to visit Llandaff cathedral because of the wealth of medieval architecture and beautiful graveyard. We placed the pots around the midway ledges on the W D Conybeare monument, each facing different directions to get a panorama when joined together. The photos below are the results – each was exposed between 4 and 4.5 minutes, using the first photo experiment as a guide. Some of the pin holes were very tiny so only a small circle has been developed on the paper. Since the cameras were very temperamental we didn’t have much control over what exactly was captured – the focused shots on gravestones are very eerie.

Since we were using negative photographic paper, we converted the images to positive by laying them shiny side down on a fresh strip of photographic paper and used the enlarger to expose for a few seconds (between 7 and 9 worked best) before developing. These positives were cut up into squares and glued to a cardboard cube to create a kind of 360 degree panorama of the graveyard. Ingrid Murphy introduced us to a couple of apps for augmented reality called Aurasma and Augment. Our aim was to use Aurasma so that when you scanned the cube in the app it would play our recorded sound of birdsong and footsteps on the paving stones from the graveyard. Since we couldn’t upload just a sound file, we tried making videos using a number of apps but unfortunately none would work when uploaded to Aurasma. It would be great if there was some way of placing the sound inside the cube so it plays when you look at it – the inner space would become a kind of capsule for the time we spent in the graveyard.

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We encountered a few difficulties along the way during this project – the gaffer tape wouldn’t stick very well to the dried clay which may be why some of the cameras didn’t work. We used six clay ones in total but only three of them produced consistent results, the others somehow let in light and overexposed the paper. Despite this I’ve enjoyed this field lab the most. I love the mysterious, cloudy quality of photos taken this way and developing them in the dark room is very similar to firing glazes in a kiln in that you’re never quite sure what the results will be like, only you get results much faster.

Colouring clay – pastel slips

This morning I opened test kiln no 3 that I fired to 1060C on Friday. The cone (06) bent at 1063C so the monitor was an accurate reading of the kiln’s temperature this time. These test pieces are a series of LF bowls thrown off the hump and painted in coloured slips then coated in an EW transparent glaze to an Emmanuel Cooper recipe:

High alkaline frit                            10
Standard borax frit                        50
Ball clay                                             30
Cornish stone                                  10

After admiring the work of Chloe Peytermann and Ben Fiess I painted a series of gouache abstract patterns in a similar palette of pastel colours then tried making these colours in slip to apply to clay.

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For the coloured slips I mixed Ball clay and China clay in equal parts then added 6% stain in primary colours: cobalt blue, red/orange and yellow. I’m disappointed with the results. 6% makes the colours soft but they’re no where close to the shades in the painting. The black slip (made with red clay recipe not stain) turned out brown and watered down while the pink is a sickly, fleshy colour although I can see it working nicely on sculptural forms. I feel a matte surface would complement the colours better – the shininess looks tacky.The colours didn’t mix as I expected either. The green turned out turquoise and the purple stayed pink.
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The flatness and precision of this decorating style bothers me but then again I’m tempted to cheat and just paint gouache straight onto bisqued clay, sticking two fingers up at Christopher Dresser’s principle of ‘Truth to materials’ in order to get better vibrancy of colour. I like the illustrative qualities you can get by painting slips and they can look stunning like on the domestic ware of Isabel Merrick, but the results are boringly predicable.

The only surface I’m happy with is the turquoise with the eye pattern below. Paring down to three colours looks more sophisticated and these cool, calming tones remind me of the seaside.

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Reduction Firing

Last week I had the chance to fire some work in a gas kiln for the first time and the results came out today. I don’t know much about how the firing works except that the kiln chamber is starved of oxygen so oxygen is taken away from the metal oxides, but I’d like to learn more. I’m attracted to the unpredictability of the glazes in this kind of firing.

I’d prepared two reduction glazes -the first was a Crystalline pale yellow/green semi-gloss with slight speckle (1280-1300C):

Feldspar                                 37
China clay                              18
Whiting                                   15
Quartz                                      10
Lithium carbonate               9
Titanium oxide                      9
Copper carbonate                 1
Zinc oxide                               1

The feldspar I used was potash and I added Titanium dioxide as a substitute for Titanium oxide. I’ve decided to use small thrown (off the hump) vessels or sections of discarded pots for glaze tests from now on because flat tiles can’t show how much the glaze runs.

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Crystalline yellow/green on Reduction st Thomas

The second reduction glaze I made was a Chun type pale green glaze with crazing:

Potash feldspar                                  45
Quarts                                                    25
Whiting                                                  17
China clay                                              9
Bone ash                                                 2
Dolomite                                                 2
+ Red iron oxide                                    1

The colour was subtler than expected but I like it’s fresh, quiet quality. I find the random speckles of dolomite glazes like this one attractive.

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Chun type green on Reduction st Thomas

Below: Buff stoneware. Two layers of Crystalline yellow/green glaze on outside with Duck egg blue raku glaze circles and Chun glaze inside. I like the roundness of this mug’s base in contrast to the sharper cylinder forms and the pulled handle balances it well.The ribbed texture from drawing up walls inside the form is highlighted by the way the glaze has pooled and draws attention to the way the mug was made on the wheel.

Reduction st Thomas. Duck egg blue raku inside and outside painted with crystalline yellow/green with chun type on top. Painted lines in red iron oxide. The duck egg raku glaze turned out a stunning, vibrant matt blue, I only wish I’d applied it to the outside.

Reduction st Thomas with blue slip splattered on top before bisque. Chun type green painted on outside with red iron oxide lines and turquoise spots. Inside crystalline yellow/green. I enjoy using the surface of vessels as canvases to explore abstract application of slips and glazes. This layering means I get exciting and unexpected results each time although I have to document carefully what I apply.

Buff stoneware cylinder. Inside turquoise stoneware glaze. Outside crystalline yellow/green with duck egg raku over bottom half which has created a cloudy, lichen-esque pattern. Red iron oxide details. The turquoise stoneware glaze turned an almost emerald green and had a bubbled texture.

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4 layers Transparent green stoneware glaze on RsT

 

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Chun type green over crystalline yellow/green

Update: The kiln should have fired for another hour because the cone fell over instead of bending so didn’t reach optimum temperature. The glazes have been underfired which may explain why they didn’t flow much and why the raku blue was so vibrant.