Etching results in a fine, sand-textured surface that resembles limestone or sandstone and where the cement paste and sand are the predominant elements visible on the surface. The finish has been referred to, as being not dissimilar to a sugar cube.
A very good off-form surface finish with a minimum of voids – enabled by the high quality moulds that are used to manufacture precast – is required to successfully apply this finish.
An etched finish is achieved in the precast factory by washing the element with an acid solution and then scrubbing the surface to remove the outer skin, about a week after the element is removed from the mould.
The advanced manufacturing techniques which are engaged in precast concrete manufacture ensure that chloride penetration to the reinforcement is not a risk in etched precast elements.