The secret of the
Gravestones at Abney Park

Interesting details on the gravestones in Abney Park Cemetery in Stoke Newington, London. The letters look as if they were applied to the gravestones, their appearance resembles letterpress printing plates.

The secret behind it? Some of the inscriptions were chiseled and then poured or hammered with lead. The abrasion of the sandstone over the centuries made the letters appear three-dimensional. 

The Lead Lettering Index (LLI)
is used to determine
the degree of erosion
of the sandstone:
W = (f (s, t (M, E, P, F))

 The weathering
observed on gravestones
is a product of four factors:
material (M), environment (E),
process (P) and shape (F).

They can be spatially (s)
as well as in time (t).

Source: envf.port.ac.uk