derrically

A little while ago I featured Bartek Mejor’s work here and was very impressed with how technically well executed his pieces are. I sent him some questions and he was kind enough to reply. If you like to get some pointers to how to make good ceramic cast like his work, read on!

The cast you made was very thin, how is it not slumping during the fire, especially a cone 10 fire?

There are several reasons for this. At the preparation stage, I’m adding fine molochite grog to the porcelain slip (about 5% - 10%), which makes the body stronger. Also, for the few largest pieces, I have used a semi-porcelain slip, which doesn’t have the same whiteness, but is much stronger than porcelain. During the firing, I’m using so-called “setters” for all pieces with any openings. They are cast in porcelain and act like lids that prevent the distortion of the openings. I’m also using silica sand and kiln fibre to support the pieces in the kiln. All porcelain pieces are fired to 1260ºC. Apart from that, it’s a bit of a hit-or-miss game with firing porcelain, and there is a high percentage of losses in a firing. The pieces displayed in my portfolio are the ’survivors’…

Is it a commercial slip you are using?

I’m mixing my own slip from commercial porcelain (clay) sold in the UK as AB porcelain. It’s simply cheaper to mix it from clay rather than buy a ready-made slip. The mix is porcelain clay, sodium silicate, dispex and water (in the right proportions).

I am impressed by how solid and even the glazes are on your work, especially the thin ones. again is it a commercial glaze or just paint?

I’m using both commercial glazes (as on the red piece) and self-mixed glazes (as on the black piece), that have been air-brushed in layers on a bisque-fired piece. On my earlier works (the more colourful ones), I have used colour porcelain slips, (porcelain slip + commercial glaze stain) that have been sprayed into the mould using stencils. After making the pattern, the mould was filled with slip to obtain the cast. This creates a pattern that is embedded in the surface of the piece. I usually fired these porcelain pieces without a layer of transparent glaze to get a crisp, matt colour. I’ve never used paint… :)
There you have it, some good pointers to make your life of slip-casting that much easier. You can check out his portfolio to see more works. If you have any questions, you can either leave a comment here, or send them to Bartek through Coroflot’s message system.

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