Matt Glazes on Porcelain

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These are the same variations on a dolomite matt glaze as in the last glaze post. This time they’ve been fired on porcelain in oxidation 1280C. W2 (with soda feldspar) has the best white result, W1 being shinier and less brightly white while W3 has yellowish undertones. B2 is the exact kind of deep matt black I was looking for too, B1 still having a green tinge in oxidation. I’m either going to start hand building with thrown porcelain sections of covering the stoneware sculptures in porcelain slip to get these glaze results.

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Katharine Pleydell-Bouverie

Dwi di ddewis ysgrifennu post yn y Gymraeg am y tro cyntaf ers i mi gychwyn yn y brifysgol dros flwyddyn yn ôl, i weld sut mae’n teimlo i newid iaith wrth siarad am fy ngwaith.
Des i ar draws casgliad o waith cerameg Katharine Pleydell-Bouverie yn yr amgueddfa ‘Potteries’ yn Stoke, a syrthio mewn cariad hefo’i gwydreddau lludw. Roedd y gwydreddau mewn arlliwiau o las, gwyrdd a llwyd yn dibynnu ar ba fath o bren oedd wedi cael ei losgi. Yn y llyfrgell ffindiais ei rysait gwydredd lludw a chymysgais hwn hefo’r lludw oedd ar gael yn adran cerameg CSAD (dwi angen gofyn o ba goeden daeth hwn) Isod mae’r gwydredd sydd wedi cael ei danio i 1280C mewn gostyngiad.
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Rysait gwydredd afloyw syml KPB:

Lludw                          40
Feldspar potash        40
China clay                  10
Ball clay                      10
(Mae ychwanegiad o 10 gwarts yn gwneud o’n llai afloyw)

Y canlyniad ydi gwydredd gwyrdd gwelw, naturiol. Fy mwriad yw casglu lludw o gyfres o brennau gwahanol a gweld sut mae’r lliw yn newid hefo bob un. Gallaf hefyd newid y feldspar i roi effaith gwahanol (mae’r post diwethaf yn profi hyn). Dwi ddim yn sicr sut i gasglu’r prennau, gallaf brynu nhw ar-lein ond bydd y prosiect yn fwy personol os gallaf gasglu’r pren fy hun.

Dwi’n gobeithio defnyddio’r gwydreddau yma i addurno’r gyfres o jygiau dwi wedi taflu mewn clai white st Thomas. Gobeithiaf dysgu mwy am danio gostyngiad oherwydd bod y lliwiau yn fwy soffistigedig ac mae’r clai yn troi’n lliw hardd mewn awyrgylch isel mewn ocsigen. Dwi di ddod o hyd i lyfr ‘Katharine Pleydell-Bouverie: a Potter’s Life 1895-1985’ yn y llyfrgell sy’n cynnwys lluniau a ryseitiau gwydreddau wedi gwneud hefo lludw cedrwydd, cnau Ffrengig, drain, rhosyn a.y.b.. i grochenwaith caled. Er bod ei gwaith hi wedi cael ei danio hefo coed tan, dwi’n gobeithio cael effeithiau tebyg hefo tanio odyn nwy.

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Matt Glazes Cone 10.R

Thinking about the surface effects I’ve identified I liked in the past I found a Mamo Matt glaze in Jeremy Jernegan’s Dry Glazes handbook and made the following variations:

Original: MC36 (W1)
Potash feldspar                     50
Dolomite                                 20
Whiting                                   4
Calcined china clay              21
Tin oxide                                 5

W2 – Replaced feldspar with 50 Soda feldspar
W3 – Replaced feldspar with 50 Nepheline Syenite
B1 – Original recipe with 1% cobalt, 8% black iron and 3% manganese
B2 – Original recipe with 4% black glaze stain

Fired in Reduction to 1280C. It was surprising to see how just changing the feldspars could change the colour so much. The potash gives a brighter, more clinical white than soda while the nepheline syenite gives blushes of pink and orange. The manganese gives a matter, more metallic black than the stain which gave more of a dark green undertone. I like the manganese black glaze (below) a lot because of the oily way it reflects the light without being too shiny. Application is better when poured.

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Below is the piece I worked on over the weekend, throwing in sections with white st Thomas then joining them together on the wheel when leather hard. Already you can see a wide ranges of tones of light and shadow and a series of ellipses when looking through the form. I enjoyed the process of making this piece and the way the pieces slotted together like a jigsaw puzzle.  The next step is to make more of these composite forms but trying to make them less symmetrical and on a smaller scale (maquette size).

 

 

Throwing in porcelain

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Nick’s slab built box with my thrown form inside
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Distorting the inside of vessels

I’m throwing in porcelain for the first time. It’s getting easier with practice. At first I found it difficult to knead when it came from the bag but it softens up as you work it. Centering on the wheel is a challenge as it likes to come off, but perhaps this is also because I’m throwing with minimal water. Porcelain is a thirsty clay but using too much water will make it difficult to control so I’ve resorted to throwing with slip instead. I love the tones of light and dark created through these distorted inside forms but how well the light plays on them depends lots on the environment where they’re displayed.

Nick is going to create a plaster mould which we can sit these in and pour porcelain casting slip into to sit them in flat slabs. I found it more difficult to get expressive throwing rings in porcelain so had to use a stick to push them out. Unlike the stoneware bulging and rippling the porcelain wants to hold its form or just collapse completely, there is no middle ground.

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Collaborative drawing

Above are the results of our discussion with ideas for constructing a kind of porcelain igloo or box which you could go inside (or at least put your head inside). We talked about how sound might be distorted as it moves through the twisted vessel forms and how we could use boxed like the one above as bricks to construct a wall you look through. We recorded the discussions so I hope to upload those here soon.