More tests

All PS on surface membrane, testing varying thickness to influence light transmission thru use of

• Stamps on upper layer
• painting additional thickness on both layers with PS to give tree effect, or lines
• Using stencil on lower layer

Also a tile with raw frit sandwiched between the layers

  

 

 

 

 

 

 

 

I also spread a line of glass fibre ‘end’s on a part of the tile to see what happens. I predict glittery exaggerated translucency If it doesn’t overflux:

I also created a series of 20 tiles, using the technique of additional slip between the layers for creating lines across the whole piece together with scored lines and stamps to try to create a sequence of related but apparently random decorations that will modify the light transmission. Tiles separated using a rectangular cookie cutter. Each has holes at the corners so they can be formed in to a curtain for the light to shine through

 

 

 

 

 

 

 

 

 

 

Line Blends #2

Well…..nothing’s perfect. It didn’t go as hoped. I stacked the kiln with each sheet on a kiln shelf. The shelves were separated by a button of clay at each corner to stop too much warping. But – schoolboy error- when a sheet did warp a little it stuck to the shelf above if it had a liquid on it. Like the glass frit line blend which stuck completely, had to be chiselled off, and now exists as fragments stuck to cling film with sellotape. So – here they are:

What this tells me is that the concentrations advised in the articles referred to in the previous posts are too high – at 100%, 50%, 25%, 12.5% and 6.75% for FeSO4, CuSO4, K2Cr2O3 and various combinations of these.

It has to be said, however, that this was once fired from green to porcelain at 1275c so the experiment needs to be repeated with the application at the bisque stage.

CoCo3

Nothing interesting here that I don’t know already. Again the L side ones are far too concentrated. The bottom 2 are <1%.

 

Glass frits

From L to R:

Aqua, Adventurine Blue, Mariner Blue, Moss Green, Grenadine.

Concentrations:

100%, 50%, 25%, 12.5%

Bottom line is a random mix of all the concentrations made for the tests

Each colour is in a pair –  suspended in CMC or PS.

Observations:

Each CMC part looks blobby but retains translucency. The PS parts retain a more uniform colour but are much less translucent, or not at all, depending on concentration – higher is more opaque. Moss Green goes orange in PS at high temp and in CMC at lower concentration. Grenadine is completely burnt out.

Illuminated:

metal salt 1

   

metal salt 2

 

Glass frit

 

 

 

 

 

 

 

Conclusion (sadly) – more tests!

 

Line Blends on Parian Slip

 

Several themes this week. I tried using Parian slip (PS) on surface membrane, instead of ppcs for extra whiteness. Seems strong enough as greenware without paper. Nonetheless I have made a couple of experimental thin tiles:

a) PS + ground Cellulose. Stirred in. Too small a quantity to mix with my drill attachment. Quite lumpy but flattened with rolling

b) PS + glass fibre ‘ends’. These are bits of glass fibre about 8mm long. Come in a box. Stirred in a small handful. Leave interesting fibrous appearance after painting on membrane but again disappears on rolling. Should add strength to the tile,

I made 3 Line Blends on PS, carrying on ideas raised at end of last term. I am looking for ways of using colour whilst not impairing translucency.

Surface Glass Frits for colour

This tested different concentrations of different coloured powdered glass frits, mixed with either CMC (on the left) or PS (right) under each colour

CoCo3 mixed with water

Various concentrations, placed between layers in the thin tile. Applied on blotting paper (more absorbent, burns out, leaving colour – enables clear edged shapes), or directly to slip under layer of PS before top layer of glass fibre membrane and PS applied.

Metal Salts (see color-research-on-porcelain-surfaces)

I used various concentrations of FeSO4, CuSO4, K2Cr2O7 (Potassium dichromate – toxic, requires gloves, mask and goggles) and H3PO4 ()Phosphoric acid). The first 3 were applied to the surface of the PS in reducing concentrations and also 2 of each were mixed in a fixed proportion and then in 2 dilutions. The last was applied as a drop to the centre of 2 different concentrations of the 3 salts. It will in some cases cause the salt to migrate to the edge of the patch. We’ll see. The articles referred to previously advise that the salts are applied to bisque. I didn’t have time to fire twice so I’ve just applied it to greenware. We’ll see again! It would be interesting to apply in the middle of the layers on blotting paper – another test for later.

Ideas for 2015

(1) Parian slip ….+/- paper

….+/-glass fibre ‘ends’

(2) Metal salts as used by

Arne As

John Shirley

The salts are: CuSO4, FeSO4, NiSO4, CoSO4, K(Cr02)2,HPO3 and others. alone or in combination In solution (5 – 100%). Often best fired in reduction. Applied to the bisque. Remain translucent.

See: Watercolours On Porcelain (Ceramics Today), color-research-on-porcelain-surfaces (A. Feyza Cakir Ozgundogdu)

While I’ve been away……

I’ve been doing my assignment (in on time), Christmas for endless streams of family, rugby stuff, and just recently preparing this term’s assignment – a survey of ceramic artists who use translucency, looking at emotional, perceptual and aesthetic intentions and responses to translucency. The relevant literature in semiotics and aesthetics is actually more interesting than I dared hope. That’s a sentence I never thought I’d write! I hope DB thinks it’s ok as a proposal. Then I’ll need to get some stats advice from the University and some translations. I can get German & Japanese done.

DB showed us some throwing techniques last week and I spent a fun afternoon making vessels. Not good, it’s true, but definitely better than I expected. None survived because I sliced them all to ensure the cross section was ok. Which it generally was. I would hope, at least, to use these rudimentary skills to make moulds for my layered stuff. Maybe even some proper potter’s pots.

The final event last term was a Show & Tell of our recent work. I was anxious but the group were kind.  That was the last stuff I made:

Usual technique. Also used coloured glass powder (frit), mixed with slip (ad hoc, no proportions) to see if I could include it in the layers, or use it as surface colour. Mixed with clay so it could be painted on. Recently wondered if it could be mixed with dilute gum arabic for same effect. With clay the colour is significantly diluted. Could also add colourant (oxide or fritted colour) to the mixture. In the layers it fluxes the clay til it bloats so I don’t think that will work.

Surface glass frit. Started off aquamarine!

The ‘ladder’ was made by touching the wet slip with the edge of a piece of card.

Flat piece, fired at 1270C standing on a shelf support, then inverted to make a bowl. Technique derived from glass slumping.

The fluxed glass is clear here:

Bubbles!

This didn’t work. It is a combination of fibreglass layered slip at the top with rolled ppc luted to the bottom. Attempted to achieve some consistency by carrying on the lower inclusions into the upper area with slip indented with edge of paper. The junction looks awful. Maybe some good will eventually come of it. But this isn’t it.

Tree silhouette using painted, uncoloured ppc slip

Coloured paper in the layers. At the top is a stamp mark

And so on to a new term…….

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