This centrifuge was designed and built in around 1900 by the Scottish-based Watson Laidlaw and Company and was installed at the Colas company tar distillery in Tonbridge, Kent during the early 20th century.

This equipment is approximately 2.5 metres tall, 1,6 metres wide, 3 metres long and roughly weighed 3 tonnes. The centrifuge has two main parts, the cylindrical chamber where the ‘fractionation’ spinning process takes places, and a larger motor and frame attached behind the chamber. The majority of the centrifuge, including its attached motor and coal tar hopper was painted a light green.

This centrifuge was built approximately in 1900 by Watson Laidlaw and Co, a Scottish engineering company which specialised in the development and manufacturing of centrifugal machines, hydro-extractors and separators. These machines were crucial pieces of equipment in the sugar, dairy, chemical, laundry and textile industries.

Before the Second World War, the petrochemical industry was still relatively small in scale, and so the primary source of organic chemicals came from smaller businesses like tar distilleries which would distil coal tar to produce crucial raw materials.

This particular centrifuge was used at the Colas company tar distillery in Tonbridge, Kent to extract naphthalene from coal tar, which itself is a by-product of the distillation of coal into coke. Naphthalene is a very simple hydrocarbon which takes the form of a strong-smelling white crystalline solid and is an important organic chemical most often used as a raw material for the manufacturing of other substances, notably phthalic anhydride which was a crucial chemical in the making of dyestuffs, and as a plasticiser in the burgeoning plastics industry.

The centrifuge works by separating coal tar into over a dozen other compounds, the most abundant of which being naphthalene, through a process called ‘fractionation’ in which the centrifuge spins the coal tar mixture at fast speeds.

Collections Review assessment drawing on tech files, and secondary sources.