Look up blunger in Wiktionary, the free dictionary.
A blunger is a machine commonly used in the pottery industry for mixing clay and water. A blunger usually consists of a round or octagonal tank with a mixer. Clay is added to the water-filled blunger and then mixed into a slurry, which is also called slip. This slip can be then sieved and magnetted as it is emptied from the blunger.
In the potbanks around Stoke-on-Trent the blunger was fed by the "sliphouse blunger charger" who was often assisted by the "sliphouse blunger charger's mate". Different types and amounts of clay and marl had to be shovelled in manually to be mixed with water.
Blungers are often used in the kaolin mining industry to mix certain grades of kaolin clay with water.