Fullers Earth is a stiff clay with a waxy appearance and it can be either blue, grey or yellow in colour. Like most clays, it is mostly made up of silicon and aluminium but it has traces of many other minerals. Its most useful property is that it is an efficient absorber in powder form. It gets the name from ‘Fulling’, which is the process of removing grease from woollen cloth. Kent used to be an important wool producer in the 17th century and Fullers Earth was required in great quantities by the Fulling Mills which processed the cloth. It was so valuable once that a law was passed banning its export and a London merchant was heavily fined in 1630 for sending some to Holland. It is now used in face care cosmetics, cat litter and to absorb agents used in Chemical Warfare.
The Kent industry was centred on Maidstone with deposits occurring in an area 9 miles long and 3 miles wide, from West Mailing to Leeds. There were once 13 Fulling Mills on the River Loose alone but by 1776 this had been reduced to only 1. The sites of these mills can be traced with a little research and one on the River Len has given its name to Fulling Mill Farm near Leeds. In this area, the Fullers Earth was found in beds up to 7ft thick but it was at a depth of 30ft, being underneath other strata. This made opencast quarrying uneconomical because a vast amount of material would have to be removed first and a large area would be required for the spoil tips. The method employed was to sink wide shafts down to the deposits which, after the Fullers Earth had been extracted, were abandoned. It is not known if horizontal workings led off from the shaft since the roof would require strong support and it was easier to sink another shaft. Underground mining for Fullers Earth did take place in Surrey, however, and it is possible that this was the local practice as well. The whole area would have been pitted with abandoned shafts and a report in 1790 (when the mining had almost died out) stated ‘ . . . there is a pit in work near Maidstone where a large space of ground has been worked over’. There was a brief period of reworking this century near Leeds and Grove Green but these were opencast sites.
In view of the age of the workings, present day remains are scant and consist only of hummocky ground where the shafts have been infilled and planted with trees. Near Barming, such areas occur at Oaken Wood and Fullingpits Wood. Near Grove Green, they can be found at Lower Fullingpits Wood and there were also others at Upper Fullingpits Wood until it was recently built upon. There are probably many more yet to be found. Grove Green was a much-worked area and the actual word ‘Grove’ was an old term for a mine. Much of the area is being built upon and sites are becoming obscured.