31.08.2009, 04:16
Oast houses were designed to dry hops (Humulus lupulus L.), the climbing plants whose dried female flowers became a vital ingredient in the brewing of beer, which overtook traditional ale (brewed with just malt) in popularity following the introduction of hops in the 17th century. Hops add flavour and aroma to beer, making it clearer and less perishable. Thanks to hops the modern British drink of 'bitter' was born.
Once picked, the hops needed to be dried on the day of harvest, and this explains the proliferation of oast houses in the main hop growing areas. An oast consists of a 'barn' section, together with the distinctive 'kiln' or 'roundel.' In the barn fresh hops from the gardens were unloaded, and dried hops were cooled on the upper floor before being packed and pressed into large Hessian sacks, called pockets. The upper floor of the kiln consisted of a latticed floor of wood and wire onto which the green hops were laid. A fire was lit below and the air channelled through the floor to dry the hops. In the 19th century fires were usually fueled by coal or coke, but later gas and oil-fired burners took over. The humid air driven off the crop was channelled up the conical roof of the kiln and out through the distinctive wooden cowl. These were usually designed with a vane, which swung round with the wind and ensured a good draught to feed the fire. Maintaining the right amount of heat at the right time was another skilful job, and specialist 'Oasties' were employed for the hopping season.
Oast kilns began as square towers which were easier to build. Around 1840 it was decided that the heat distribution was better in round kilns and so this became the predominant design. However, as science advanced it was proved that square kilns were more efficient after all. As a result, square kilns regained their popularity in the 1890s. Most kilns are topped with the familiar white-painted cowl and weather vane, but some, especially those along the Kent and Sussex border, have a simpler, squatter, wooden chimney-type of vent.
Once picked, the hops needed to be dried on the day of harvest, and this explains the proliferation of oast houses in the main hop growing areas. An oast consists of a 'barn' section, together with the distinctive 'kiln' or 'roundel.' In the barn fresh hops from the gardens were unloaded, and dried hops were cooled on the upper floor before being packed and pressed into large Hessian sacks, called pockets. The upper floor of the kiln consisted of a latticed floor of wood and wire onto which the green hops were laid. A fire was lit below and the air channelled through the floor to dry the hops. In the 19th century fires were usually fueled by coal or coke, but later gas and oil-fired burners took over. The humid air driven off the crop was channelled up the conical roof of the kiln and out through the distinctive wooden cowl. These were usually designed with a vane, which swung round with the wind and ensured a good draught to feed the fire. Maintaining the right amount of heat at the right time was another skilful job, and specialist 'Oasties' were employed for the hopping season.
Oast kilns began as square towers which were easier to build. Around 1840 it was decided that the heat distribution was better in round kilns and so this became the predominant design. However, as science advanced it was proved that square kilns were more efficient after all. As a result, square kilns regained their popularity in the 1890s. Most kilns are topped with the familiar white-painted cowl and weather vane, but some, especially those along the Kent and Sussex border, have a simpler, squatter, wooden chimney-type of vent.