Have you ever wondered how your porcelain is made? There are many variations in appearance, quality and production of porcelain. We here provide you with an overview of the differences and concepts. Porcelain paste is mixed from kaolin, quartz and feldspar. Depending on firing temperature and mixing ratio of the raw materials one can distinguish different types of porcelain.
Generally, it is fired and glazed twice. It first turns bright and then becomes translucent. Porcelain is acid resistant and well insulated against electricity and is a poor conductor of heat.
Hard porcelain – hard paste porcelain is fired at about 1,400 ° and consists of about 50% kaolin, 25% quartz and 25% feldspar. The high kaolin content makes it pure white. The high temperature makes it dishwasher safe and also hard.
Soft- paste porcelain is fired at about 1,280 °. However it consists of only 25% of kaolin and rather 45% quartz and 30% feldspar. Soft-paste porcelain is sensitive to temperature variations than hard porcelain and significantly impact-sensitive.
Bone china is fired at about 1,280 ° and contains a high proportion of quartz instead of bone ash with calcium phosphate. This makes the delicate and thin material tremendously dense, firm and transparent.
Bisque is unglazed hard porcelain with a matte finish.
Stoneware, earthenware – stoneware and earthenware contains kaolin clay instead. Stoneware is fired at a low temperature and, unlike stoneware, it is not waterproof, so it must be glazed.
Turning – plates and relatively shallow bowls are rotated on a plaster mold. Cups and deep bowls are fitted with rotating roller heads in a negative form. Only a few companies turn porcelain traditionally today.
Pressing – isostatic pressing process presses porcelain granules with 270-300 pressure and molds them in plate shapes. The majority of industrial plates are manufactured by this method.
Molds as cans, figures and spouts use the liquid porcelain, which are also poured into negative molds of plaster.
Foil décor – Wet color films with screen-printed motifs are applied and then baked.
Surface décor – Large monochromatic areas are applied with a spray gun.
Hand painting –
Hand-painting today also uses all gold and platinum paints and still forms a large proportion of m porcelain manufacturing. Handpainting include precious vases and collection plates. It is either painted on the glaze or on the blank porcelain, which is then glazed and fired to smoothen. Also metallic luster glazes, gold and platinum bands are often painted by hand.
Lamination – The most common and much less expensive technique to decorate porcelain is placing a very thin, wet color film. Decorative films are mainly produced by screen printing.
Stamp decors – Most gold decorations are made with punches either directly on the porcelain or color is melted over the porcelain.
High-temperature designs – High-temperature designs are applied either with color film, airbrush or hand painting on the finished baked porcelain. Many shades including gold and platinum can be added with this method as they are melted into the glaze: The porcelain is heated to 1,250 ° C, so that the decors sink into the liquefied glaze and are protected by it. Advantage: high temperature decorations are dishwasher safe and resistant to surface effects.