Defects Generated During Decaling Operations

Ceramic decals have been used for decades to enhance the value of ceramic products. Hand painting using colored glazes (enamels) is more expensive and the production rates are much slower. However, the ware may be more valuble than decaled ware.
Silk screening allows heavier color deposition.
The process to make a decal is to add colored oxides to drying solvents and binders to form an ink. The colors are printed or silk screened each color individually onto a special decal paper. A cover coat is applied to the printed decal sheet before the final drying of the decal sheets.
(It’s a pretty stinky process. Several color separations are used. For fine china, seven passes through the silk screening process are often required to obtain the color detail desired. Go to [http://www.ceramicindustry.com/CDA/ArticleInformation/features/BNP__Features__Item/0],2710,80851,00.html.
Decals are typically printed on large sheets. A worker cuts the sheets into individual decals and places them into water (usually with a wetting agent) where they soak until another worker slides the decal off the paper and places it on the ceramic ware.
Decaling is a low-loss process. If there is a flaw in the decal after firing the ware usually must be scrapped. Now days, enamel and or precious metal are often incorporated in decals.
If precious metal is added separately, it still saves one firing.