Glass decoration is the range of techniques used to ornament glass, either while it is being formed hot or after it has cooled. Hot techniques include colouring the batch, trailing, applied prunts and threads, millefiori, casing and iridescent finishes, while cold techniques include cutting, engraving, etching, sandblasting, enamelling, gilding and painting.
Each era and region has its characteristic methods. Venetian glassmakers of the Renaissance excelled at thin, coloured and filigree glass worked at the furnace, while Bohemian and German workshops became renowned for wheel engraving and cutting in the seventeenth and eighteenth centuries. English lead crystal, introduced in the late seventeenth century, proved ideal for deep cutting, and Georgian and Regency cut glass decanters and chandeliers became famous. The nineteenth century added acid etching, pressed glass, cameo carving and transfer techniques, and Art Nouveau makers such as Gallé and Tiffany explored layered, iridescent and organic effects. When assessing decorated glass, collectors consider the skill and sharpness of the work, whether it is hand-executed or mechanical, and whether decoration is original. Later additions to plain old glass, such as engraving or enamelling, are known and can mislead the unwary.
