What is flint?

Flint is a mixture of crystalline silica (quartz) and hydrated silica (opal). Flint can vary in all shapes, sizes and colours. There are three main types used in construction: quarried flints (also known as virgin flints); field flints; and cobbles. The exact origins is still unclear though much debated. The most accepted origins is that it probably derives from the remains of minute sea organisms with a skeleton of silica.

Geology and history

Flint can be found in many places across Southern England, though is particularly prevalent in parts of Sussex and East Anglia. Found as a free and indigenous material in the Middle and Upper Chalk layers it has always been used in construction. Though since late 19th Century due to a combination of less quarrying, other alternative materials and improvement in the transportation system, less flint has been used in buildings.

Treatment and uses in construction

There are many different styles of flint work in construction, from field flints harvested from the local fields to fine well worked knapped flint. Over time structures changed from being purely functional to more decorative. Exact style and use of the flint would often reflect on the afflence of the owner or the importance or prominence of the building or structure. Often fine knapped flints would be used on the main house, with less worked field flints used on boundary walls. Most walls are either freestanding or retaining.

The flints are held in place by mortar. Traditionally this is made up of a combination of lime and sand. The exact proportions and type of aggregate and binder would vary depending on the existing mortar to be matched. Historically both would come from local sources. Most walls have been constructed by either shuttering or freehand. The latter being the much prefered style of construction. More modern methods also include flint clad concrete blocks or dyed reconstitued stone. Both methods result in poor asethetics and often poor adhesision. It is a myth that these modern methods will reduce costs.