Methods of producing ceramic piggy banks
- On the potter’s wheel: This is modelling a piggy bank like a pot on a potter’s wheel. Potters are not too keen on making piggy banks this way.
- Free modelling: ‘Free modelling’ is an artistic method. The results are fantastic, but very few potters do it this way.
- Moulding: Most frequently used is moulding. Inside the mould you find the ‘negative’ image of the piggy bank. Slip clay is poured into the mould, water is soaked up in the absorbent mould. All is left to dry for a small period and then the rest of the slip clay is poured out again. To pour out the slip a piggy bank needs to have a hole. That’s probably one of the reasons modern piggybanks have stoppers. Makers of old fashioned piggy banks used creative means to let the slip go: a hole where the tail later was put on, or through one or more legs. The traditional opening for the coins is cut in the raw material before firing. See my blog (2015/12/01).
A second moulding method for making piggy banks is to use two halves of a mould, and to glue the raw forms together with slip. When done professionally no ‘seam’ is to be seen. Old and antique piggy banks often do show this seam. An identifying mark! The result of both methods is a piggy bank that has to dry further and then to be fired in the oven. When fired it’s called ‘biscuit’.
- Folding: An obsolete method because of the labour intensity. Nowadays used bij potters on fairs. See my blog called "Folding" (2018/01/01).
Terms connected with earthenware
- 'Bisque' of 'biscuit' earthenware is simply the once-fired body without the addition of glaze. Green ware is unfired pottery, ready to be bisque fired.
- Terracotta: Unglazed porous earthenware, mostly red.
- Slip (liquefied clay) is used in casting and to decorate earthenware.
- Carving: Like woodcarving removing areas of clay in the raw model, to create a raised design. After carving the object is baked and then glazed.
- Plaster: Used to make moulds but was also used (especially in France) to create figurines and piggy banks. The process is the same as clay slip in moulds. There is no baking process, the plaster dries in the air and is painted after drying.
- Stoneware: It became known in northern Europe after the Renaissance. Probably the majority of current glazed stoneware are salt glazed (part of the baking process).
- Siderolith: White or colored volcanic clay, baked as stoneware. But Siderolith does not form a glass layer on top as stoneware does. It is finished with copper varnish. Production between 1880 and 1930. Much wanted by collectors!
- Glaze: A thin coating of glass. An impervious silicate coating, which develops in clay ware by the fusion under heat of inorganic materials. Applied to porcelain or pottery body to make it waterproof and enhance colour. Glazes may be clear, opaque or coloured to various degrees.
- Lead glaze: transparent glassy glaze using lead oxide, colour green. Due to EC regulations forbidden for household use, because it is poisonous.
- Tin-based glaze is white, glossy and opaque, normally applied to red or buff earthenware. The opacity and whiteness of tin glaze make it valued by the ability to decorate it with colour.
- Painting: paint over tin-based glaze or plaster.
- Lustre: A type of decoration originally developed in Persia that leaves a thin layer of metal on the decorated portions of pottery.