If you are an artist or sculptor and are thinking about taking on a commission to do an outdoor piece think carefully about its vulnerability to spalling if it will experience freezing temperatures (see linked article below). The construction industry deals with this issue every day, take a cue from their experience.
Outdoor Weather Resistant Ceramics
How can you be sure that the porosity of your fired ceramic ware is low enough to prevent freeze-thaw breakdown in the winter?
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