Uniroll Wet Milling machine made by Vickers Armstrong installed 1949

This Uniroll wet milling machines was built by engineering conglomerate Vickers-Armstrong and sold in 1949 to Waterlow and Sons, a London-based engraving and printing company which operated from 1910 to 1961. The purpose of this single roll design of milling machine was to refine inks which would be used by the company to create stamps, bonds and other forms of prints.

The production of fine inks, especially in the mid-20th century, often had several stages. The first stage is always being mixing solid particles of pigment (which holds the colour) with a fluid ink vehicle (such as an oil) which the pigment dissolves or attaches to. Some types of pigment particles are too hard or large to properly mix with the fluid, and so the mixture needs to be ground down and refined into finer particles. Some inks might need several stages of progressively finer milling and grinding but will eventually be finished in a final filtration stage.

Wet milling machines such as this Uniroll design uses hydraulic pressure (via a single cylinder oil pump) to facilitate the grinding down and refining of the ink material and forces the material into a tight particle grinding and rubbing section. The refined material is retrieved from the machine in the form of a thin film which is removed via an automatic scraper. The roller which moves the material through the machine required a water-cooling system to prevent it from getting too hot.