Spray process for the chemical determination of free halogen and pseudohalogen ions, in particular chlorine ions, on surfaces or fracture surfaces of materials

摘要

The invention achieves the object of detecting free halogen and pseudohalogen ions, in particular chlorine ions, on the surface or fracture surface of porous and non-porous materials. For this purpose a special spray gun made of corrosion-resistant material is used, with which silver nitrate, potassium chromate and optionally citrate buffer solution can be applied in sequence in the form of aerosols to the material surface. This results in precipitation of silver chloride in regions containing free chlorine ions. The other regions are coloured brown or reddish brown (carbonated concrete region). Subsequent action of artificial or natural UV light causes the colour of the AgCl-containing region to change to grey. The residual region changes to a black colour after a longer period of time.