Ceramic 3D printing tests 05 - Yet more...

18.06.13

Only 3 days left here in Oslo and suddenly I'm trying to work out how to fire more kilns than time allows! However, Knut who runs the ceramic workshop has asked me to use a larger kiln that has extraction. The sugars in the ceramic mix were filling the (huge) kiln room with caramelly smells (& smoke). The good thing about the larger kiln is that the cooling can be controlled and assisisted by fans, so I stand a chance to get the majority of the tests through.

Here's the results of the 1100°C firing. The only reason that the red clay bars are broken is that we (very non-scientifically) broke them to see how strong they are in the green, unfired state. The sugars actually make them fairly difficult to break, there was a certain amount of stretching, rather than a simple, clean snap. It gives you more confidence when removing pieces from the printer, though after 2 hours they are still flexible. We find that leaving them overnight is best.





Yesterday afternoon, Trine introduced me to some more tools in the modo software toolbox. I hoped to print a ceramic version of my Prtlnd Vase, an interpretation of the Portland Vase. I produced it in nylon by SLS and it was recently acquired through the Art Fund at Collect for the New Walk Gallery in Leicester.

The handles on the original CAD file are a little thin for ceramic printing and modo was a very useful for rebuilding them intuitively. The software also tidied up the mesh and considerably reduced the file size.
I was keen to build this as large as possible which meant converting all the Potclays powder to 1:1:4 which we think is the strongest of our trials. Trine had mixed some more yesterday, so that was sieved together with the rest and there was enough to completely fill the feed chamber. I had a conversation with Trond, who looks afetr the machines in D-Form. He suggested that the binder settings should be reduced as it could be the cause of the deformation in the build. He thinks they could simply be too wet. So I reduced the Shell to 85% and the Core to 70%. We will see if it has the desired effect.

After putting the build on, I mixed up a lovely lead-based clear earthenware glaze. The recipes that we have used for many years in the studio at home are Lead Sesquisilicate based, but they don't stock it at KHIO (who does?). The recipe I used is taken from 'The Potters Palette' by Christine Constant and Steve Ogden, an excellent source of some fabulous glaze recipes and shamefully out of print.

Lead Bisilicate 65
Whiting 10
Potash Felspar 15
China Clay 10

Fire to 1085°C with a 20 minute soak. A small amount of liquid calcium chloride added to the glaze prevents it from settling out and aids even glazing. But be cautious, if you add too much you can turn the glaze into the consistency of blancmange!

These pieces were popped into the kiln along with some vitreous slipped pieces. The plan for tomorrow is to slip and refire as much as possible and then glaze and fire them.

And then I'll hopefully have time to squeeze the Prtlnd Vase into a firing before my early morning flight back to the UK on Friday morning.