3 октября, 2015 
Malyar The use of water borne coatings on steel can, in certain instances, lead to flash rusting, which is the rapid and irreversible formation of rust. This is especially true under conditions of high humidity, where the water component of the formulation remains in contact with the metal for extended periods of time, when the evaporation is slow.
This can be remedied by increasing the pH of the paint to 8 — 8.5.
The use of slower evaporating amines, such as triethylamine or di-methyl amino ethanol, will maintain the desired pH over a greater period of time, but will significantly delay the onset of water resistance offered by the film.
Alternatively, flash rusting may be prevented by the use of ammonium benzoate, sodium nitrite or ammonium dichromate. In instances where the coating is to be applied to copper or brass, the ammonium ions in ammonium benzoate and ammonium dichromate will react with the metals, leading to dullness or discoloration. This effect can be neutralised with a small addition of benzotriazole.
Опубликовано в рубрике 