Characteristics
Soft-paste made with little clay is not very plastic and shaping it on the potter's wheel is difficult. Those pastes with more clay (now more commonly referred to as "bodies"), such as electrical porcelain, are extremely plastic and can be shaped by methods such as jolleying and turning. It was called "soft" because of its inability to hold rigid under high temperatures compared to hard-paste porcelain. The feldspathic formulations are, however, more resilient and suffer less pyroplastic deformation. Soft-paste is fired at lower temperatures than hard-paste porcelain, typically around 1100oC for the frit based compositions and 1200 to 1250oC for those using feldspars or nepheline syenites as the primary flux. The lower firing temperature gives artists and manufacturers some benefits, including a wider palette of colours for decoration and reduced fuel consumption. The body of soft-paste is more granular than hard-paste porcelain, less glass being formed in the firing process.
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