ESDA is the leading technology for detecting indented writing on questioned documents. ESDA works by creating an invisible electrostatic image of indented writing, which is then visualised by the application of charge sensitive toners. The sensitive imaging process reacts to sites of microscopic damage to fibres at the surface of a document, which have been created by abrasive interaction with overlying surfaces during the act of handwriting.

– More sensitive than oblique lighting

– Simple to operate

– Produces permanent 1 to 1 transparencies

– Responds only to indented writing – ignores visible script

– Non-destructive – leaves documents uncontaminated