After 1850 manufacturers began to impress their initials, names or companies into the unfired brick.
Machine pressed bricks were a Victorian development; contemporary architects liked a standard product of a uniform colour with smooth faces and sharp arrises.
Such a brick required machine-making and kiln firing.
After 1850 this tax was rescinded and there was no motive for making a brick any larger than could be conveniently handled by a brick-layer.
Bricks slowly became thinner once more showing a slow decline to 2 5/8inch.
Several methods of scientifically dating individual bricks have been explored.
The most promising is rehydroxylation dating (RHX).Some experts believe that the moulds show enough individuality for the work of single brick-makers to be recognised.The repeating arrangement of bricks in a wall is called the ‘bonding’.A building showing Flemish Bond must be later than 1631, and effectively the arrangement dates a building to after the late 17 century to reach 3” – 3½”.To some extent this was the result of a government imposed brick tax based on the number of bricks a manufacturer produced.Secondly, any attempt to date British bricks stylistically must allow for regional variations; the size of pre-18 century bricks, and their arrangement, did not conform to any nationwide standards.