A close look at crystals

The complexity of silicate chemistry is formidable. Silicates surround us. The crust of our planet is largely composed of silicate rock in its many forms. Crystalline glazes are one tiny expression of this rich universe of complexity. At the lower level they are just arrangements of atoms, at a higher level of organisation, inhabited by entities such as us with an evolved aesthetic appreciation, they dazzle and excite. A deeper understanding does not detract in my opinion. Richard Feynman, physicist, and an inspiration during my teenage years, puts it very well:

 

 

 

I have a friend who’s an artist and has sometimes taken a view which I don’t agree with very well. He’ll hold up a flower and say “look how beautiful it is,” and I’ll agree. Then he says “I as an artist can see how beautiful this is but you as a scientist take this all apart and it becomes a dull thing,” and I think that he’s kind of nutty. First of all, the beauty that he sees is available to other people and to me too, I believe, although I might not be quite as refined aesthetically as he is, I can appreciate the beauty of a flower. At the same time, I see much more about the flower than he sees. I could imagine the cells in there, the complicated actions inside, which also have a beauty. I mean it’s not just beauty at this dimension, at one centimetre; there’s also beauty at smaller dimensions, the inner structure, also the processes. The fact that the colours in the flower evolved in order to attract insects to pollinate it is interesting; it means that insects can see the colour. It adds a question: does this aesthetic sense also exist in the lower forms? Why is it aesthetic? All kinds of interesting questions which the science knowledge only adds to the excitement, the mystery and the awe of a flower. It only adds. I don’t understand how it subtracts.

Richard Feynman. BBC television interview 1981.

 

 


 

 

This is a detail from a glaze in development. It produces golden primary crystals set on a pale green opaque ground featuring a thick dusting of golden brown secondaries. The challenge is getting consistent results with both the primary and secondary. I can alter the composition to favour either but the region I’m interested in where both are developed is extremely small and the glaze is unreliable at the moment.

 

 

 

 

Detail from my gold green glaze.

 

 

 

Detail of the secondary crystals in my gold green glaze.

 

 


 

 

Crystalline glazes based on chemistries other than zinc silicate have been a recent development in my work. The glazes below include examples of my iron red, tea dust and aventurine.

 

 

 

 

Iron red.

 

 

 

A variant of my iron red using a formulation based on Alberta Slip.

 

 

 

Interaction of my tea dust glaze (left) and aventurine (running down from the top). My aventurine cannot be made from commercially available materials. I use a special frit that I make myself to get the effect.

 

 

 

Detail of iron aventurine. Approximately 3mm x 2mm. The chemistry of this glaze makes it difficult to match the thermal expansion coefficient with the body. The glaze crazes as a result.

 

 


 

 

My pale green/blue glaze has many variations – very small adjustments to the balance of fluxing oxides can transform the glaze.

 

 

 

 

Detail showing the primary crystal fringe and needle form secondaries.

 

 


 

 

My glazes occupy a niche within a niche: the large primaries are a challenge but getting them together with secondary crystal formation is on a different level of difficulty. Putting a piece through the glaze firing twice often produces additional complexity with the secondaries. I don’t often do this but sometimes a piece comes out not looking as I would like, a second firing is high risk, the failure rate high, but often brings about a spectacular transformation. Many of my favourite pieces are of this type.

 

 

 

 

Glaze fired twice, the secondary formation is especially powerful in this example.

 

 


 

 

Growth rings are achieved by varying the kiln temperature as the crystals are growing.

 

 

 

There are two variants of the secondary crystals in my mid blue purple glaze. Shown here is the fringe of one of the primaries surrounded by blue and purple secondaries.

 

 

 


 

 

 

A closeup of the secondary crystals in my mid blue purple glaze. The image represents an area of approximately 9mm x 6mm. The texture of the primary crystal can also be clearly seen,

 

 


 

 

 

Dark blue glaze. Approximately 30mm x 45mm.

 

 

 

Detail from the bottom left region. Approximately 5mm x 3mm.

 

 

 

An extreme closeup of my dark blue glaze (#3541). The image covers an area of approximately 3mm x 2mm.

 

 


 

 

 

Blue green speckled glaze. The feathery structure within the primary crystal can be seen clearly. approximately 10mm x 6mm.

 

 

 

Detail of blue green speckle. Approximately 4mm x 3mm.

 

 


 

 

 

Detail from a cup with my pale green/tan crystalline glaze. Approximately 3mm x 2mm.

 

 

 

A darker version on the pale green tan over my casting porcelain.

 

 

 

The primary fringe and two types of secondary in my pale green tan.

 

 


 

 

 

An interloper in the zinc silicate landscape, this delightful entity is 5mm wide.

 

 

 

Another of the fern-like crystals.

 

 


 

 

 

Transition between the blue and purple secondaries in my mid blue glaze. The image shows that the two colours of secondary are the same type of crystal but with different colour. There appears to be a concentration gradient of the element responsible for the colour.

 

 

 

The fern-type crystals are also present in the blue purple glaze but the contrast is lower. This image has been sharpened to bring out the structure clearly.