The bricks used for this purpose are known as 'rubbers' [or cutters] and consist of finely sieved brick earth fired to below 900 degrees [vitrification temperature]. As a consequence rubbers are relatively soft compared to a standard brick. Rubbers may be cut by means of a bow saw or rubbed by means of a rubbing stone. Once the desired dimensions are achieved rubbers are soaked in water and dipped into a lime putty and silver sand mortar prior to being laid. By this method joints of less than 1mm can be achieved. As with stone, gauged brickwork can be carved to create beautiful embellishments. This is a highly skilled and time-consuming process.