Bleiglasuren

Bleiglasur is a glaze used in ceramics that contains lead oxide as a flux. The lead lowers the glaze’s melting point and promotes a smooth, glassy surface, often with a bright, transparent or luminous finish. It is commonly applied to earthenware and porcelain and tends to mature at relatively low firing temperatures compared with many lead-free glazes.

Composition and properties: A typical Bleiglasur combines silica and alumina with lead oxide, sometimes together with other fluxes or stabilizers. Colorants such as copper, cobalt, manganese or iron can be added to create greens, blues, yellows or reds. The lead-based matrix yields good gloss, strong adhesion to porous bodies, and clear or bright visual effects at low to mid-range temperatures.

Historical usage: Lead glazes have a long history in European ceramics, especially in faience and majolica. They enabled vibrant colors and a durable, glassy surface on relatively porous wares and were a standard option before the widespread availability of lead-free alternatives.

Safety and regulation: Lead-containing glazes pose a risk of lead leaching, particularly with food or drink contact or if the glaze is damaged. As a result, many jurisdictions restrict their use for functional wares. Decorative objects may be glazed with lead-containing formulations, but modern practice increasingly favors lead-free frit-based glazes, especially for any ware intended to contact food.

Contemporary status: Bleiglasur remains of historical and artistic interest and is still used by some artisans for decorative pieces. In modern production, its use is often limited and tightly regulated due to safety concerns, with lead-free alternatives preferred for functional ceramics.