Saturday 28 December 2019

Buff blue - glaze dipping to understand difference from PB103

Glazing attempt 2 - blue!

My first attempt at glazing was a single session to experiment with colour combinations and basic dip glazing techniques as dip glazing was something I'd never tried before. Those experiments were moderately successful with the blues being my favourites followed by the aubergene over green combination. For medieval ceramics through, the purple colour isn't a common one so I thought I should stick with basic colours to see if using buff clay changes much.


The first experiment was conducted on what could be my favourite little cup shape. It unfortunately developed a small crack in the base and one on the handle due to uneven drying. I hoped a solid glaze could plug any potential gaps and strengthen the cup. I had intended to put a clear glass over the matte blue however the cup slipped while I was dipping it so it absorbed too much water from the glaze and was too damp. I didn't want to add more moisture with a second layer of glaze as I was worried it wouldn't be able to be fired. Still happy with the shape as I love the little thumb divoty thing and the handle is a very pleasing size for me.
The glaze appears to have strengthened the cup and this one it nicely watertight and the handle can hold the weight of the cup full of liquid.

Experiment the second. This smallish milk jug was dipped in titanium white in the base and matte blue on the top. The inside was sealed with a transparent gloss glaze. Blue dots of 28B underglaze was added for visual appeal and to see if the older underglaze could withstand the stoneware temperatures (~1200). I am in love with this glaze blend and plan on creating a whole set of house cups for myself in this pattern.

Experiment is a success with the blue withstanding the higher firing temperatures and the buff clay body is not skewing the shades blue significantly.

Interestingly, the buff clay appears to bloom when proximal to certain types of glaze. There doesn't seem to be a significant colour change on the foot of the milk jug however there is bloom on the foot of the blue cup. The bloom is easier to see on the neck of the quatrefoil cup resulting in a pleasing reddish-brown tone. This has to be a result of a slight degassing from certain glazes interacting with the iron in the clay body as the same glazes on the PB103 do not produce this result.

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