Wednesday, 18 March 2020

Candle shades

These kinds of drapes are generically known as handkerchief drops, as they form the kind of shape that is formed by holding the cloth in the middle and letting it drape.  They can be done as small drapes over kiln posts, cocktail shakers, and much larger forms.

Two heights of new cocktail shakers

A well used cocktail shaker with kiln wash

A kiln post wrapped in preparation for firing

Two short kiln posts after firing

When preparing several drapes to be fired at one time you need to consider several factors.

Higher in the kiln is hotter.
The heat in a kiln, as in an oven, is greater the higher in the kiln is supported.  This means that taller supports will drape quicker than shorter ones. The consequence is that all the drapes should be of the same height.

A single layer that has begun to stretch at the shoulder of the former 

Larger spans fall quicker than smaller.
The more of the glass that is unsupported, the quicker it will fall, even at the same height. This is because the larger amount of unsupported glass has more mass than a smaller one and so falls quicker.  Plan for all the glass to be of similar sizes.

These two were fired at the same time. The back one is larger than the front 

Different shapes fall in different ways.
Squares and circles are the most common shapes used in a  drape. The corners of squares are points that are further away from the centre of the support than the sides.  These points begin to fall first, drawing the sides in later in the firing.  Circles form a taco shape before the ends of the “taco” begin to fall.  This deformation of the circular “taco” takes longer than a square takes.

Care needs to be taken that the glass does not thin excessively at the shoulder of the support.  There is less difficulty, if the same shapes are fired together as different heat work is required for each shape.

Observation by peeking is required to stop free drops at the right time.
As in all drapes, it is important to observe the progress of the drape at intervals.  This is best done by quick peeks to note the development of the shape and to move to the cooling segment when the drape is complete. This also requires a scheduling of a long soak and knowledge of how to advance the kiln controller to the next segment of the schedule.

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