Pressandblow

Pressandblow, also written press-and-blow, is a glassmaking technique that combines pressing and blowing to form hollow glass objects. The method integrates an initial shaping stage created by pressing molten glass into a blank mold, followed by expansion via air blowing to establish the final profile. The dual action allows controlled wall thickness and smooth exterior surfaces, enabling forms that are difficult to achieve with blowing alone.

In a typical cycle, a gob of molten glass is gathered and placed in a blank mold. A plunger or pressing tool presses the gob to form the base and interior contours. The partially formed piece is then either transferred to a blow mold or left in the blank for a second action, and air is blown through a blowpipe to expand the shape and refine the interior surfaces. The process often employs two-part molds and synchronized tooling to produce a finished hollow vessel.

Press-and-blow is commonly used with soda-lime glass, and can be applied to leaded and colored glasses in specialized production. Objects produced include bowls, vases, carafes, and other hollow ware with even thickness and a smooth exterior. Equipment combines a glass press with a blow pipe and molds, requiring skilled operation to manage temperature, timing, and mold release.

Originating in the 19th century as an evolution of traditional glassblowing, press-and-blow gained prominence in industrial glassmaking for its ability to produce consistent shapes at moderate scale. It remains in use today in studios and factories that value controlled thickness and specific decorative or functional forms, often alongside other forming methods.