Bone China and fabric

I built up two other bowls using the same method as before but using liquid bone china instead of porcelain slip. I wanted to compare the qualities of the bone china and porcelain. In theory the two types of clay are very similar.

Porcelain is fine in texture and white and tough when fired. It can be either opaque or translucent. It is notoriously difficult to handle as it has a critical moisture range to it can easily be too soft or dry to handle. It fires to 1280-1300'c.

Bone china is prepared with special characteristics of thinness, translucency, whiteness and extreme strength. Calcined bone is added which acts like a flux to the clay body making it fuse into a tough glass-like substance at temperatures above 1240'c. It has a poor mechanical strength before firing and a limited top firing range after which it quickly loses it's shape and collapses. Because of its smoothness and whiteness it is very well suited to fine decoration. In the 1980's, the ceramicist Angela Verdon made interesting slipcast pierced and scratched forms from bone china:

 Angela Verdon 1980 Porcelain

Angela Verdon 'Paper Thin Porcelain Vase

I used the same method to weave thin strips of different fabric that had been immersed in bone china slip around a balloon:

This photo was taken after the slip had dried but before firing. I stitched a strip of organza with embroidery thread using chain stitch. I used organza because it doesn't absorb the slip very well (being man-made) whereas the stitches should work well. I wanted to make the stitches stand out visually so I painted copper oxide mixed with bone china slip onto the thread. This appears black in the above photo.

This structure is incredibly delicate, perhaps more so than those in porcelain. However, this could be because I built it more delicately than those built in porcelain. I did like how the copper oxide accentuated the chain stitch however. I think that the structure has warped just as much as the porcelain but the amount of warpage will depend on the height of the structure I guess. At the moment I am learning about the materials and what happens if I do such and such to it.

I built a second piece with bone china using some fleece material so that hopefully the structure will be a little stronger:

I also used the shaggy wool as I really like the tactile quality of this when it is fired. I stitched a long strip of organza with emroidery thread and chain stitch as above but I have added more copper oxide to it. I hope I haven't overdone it but I wanted to accentuate the light and dark parts of the structure - where the fabric strips cover others so creating shadow  and lighter sections etc. The piece was left to dry over the Christmas holidays and will hopefully be fired next week.