PB103 underglazes - fine detail and black oxides

This was my first experiment with firing my new underglazes at stoneware temperatures! I was running a tile test at the same time so I really really wasn't sure how these would turn out. I was on a tight timeline so I couldn't afford to wait.

This was the first large cup I ever made with PB103. I'm very happy with the shape as the lip sits comfortably in hands slightly larger than mine. The base is still a tad thick as a result of my inexperience and my desire not to end up with another basal cracking situation. This design was hand painted using green underglaze with black outlining and detail painted over it. The whole cup was then dipped in a clear coat. Note the matte base? I plonked the foot in paraffin wax prior to the clear glaze. The wax prevents the glaze from covering the base and thus stops the glaze from fusing to the kiln shelf. Unfortunately for me, the kiln shelf held some spots of iron shed from previous firings. When the kiln was loaded, the shelves weren't coating in a resist so this cup stuck to the shelf. As a result, there are a few chips in the base. This saddens me as it was intended as a gift and it is no longer perfect. On the upside, due to the thickness of the base, this cup is still viable so I'm going to gift it anyway.

The brunswick green colour came out nicely but it does emphasise how important three coats are. Each of the outer feathers received a single brushstroke of colour running from outer to inner. This meant the second and third row of feathers had the chance of double or triple colour. It provides a nice texture for the feathers as was intended but it's something to keep in mind for future decoration.

Did you know that Siren's were originally large birds with female heads? Something like a seductive version of a harpy I guess. I only found this out a few months back and I've been gleefully spreading this knowledge to as many people as I can.

My third cup in PB103 (second one will be addressed in the next post). I was so happy with this when it came out of the kiln from the bisque firing! The sides are beautifully thin because the PB103 is a bit sticky and supports its own weight really well. It's good to handle but is susceptible to becoming too squishy if too much water / slip is used. This cup is too large for my hand but will be a nice low cup for a man. Again, the base is thick, but I played around with a deliberate flare to make it easier to tie to a belt. This was made before I knew how to trim cups once they are leather hard so this was entirely done during one pass on the wheel.

This was another attempt at decorating with bunswick green and black. In this case, the black was laid down first and the green was applied later. It seems the black doesn't necessarily required two coats but it also doesn't 'come through' the over coat very strongly. This cup is a little streaky because I forgot to mix the clear glaze before applying. As a result I had to do a second dip and I think that moved some of the underglaze particles slightly resulting in the slight fuzziness to the design. Next time, unless this is an intentional feature, I must remember to mix the glaze overcoat well prior to dipping!

Over all assessment:

Black - one or two coats is sufficient. Maintains fine detail really well. Practice shading is required.
Brunswick green - one coat can end up yellowish and may provide good variation for leaves etc. Three solid coats is a good strong colour.
Clear overglaze - the steakiness of thin glaze is actually a rather pleasant effect. I think it could be used to good effect for natural scenes or perhaps humming birds.