Kelate® has been designed so that it will react and passivate (residual) rust on CSt2-DSt2 surfaces.
Most mechanical surface treatments, such as scraping, hand brushing or power cleaning, do not remove all the rust from the cavities of the surface, and the presence of this residual rust encourages continuation of the corrosion process under paint films subsequently applied.
Blasting the surface to white metal provides an excellent substrate for paint, but a freshly blasted surface is highly reactive, and once exposed to atmospheric humidity, dew or rain, will result quickly. This means that to preserve investment in sandblasting for instance, the freshly blasted surface must be coated immediately.
Sandblasting is often ruled out due to cost, environment protection, inconvenience of rigging, dust and spark potential, limited size of areas to be cleaned, difficulty of arranging blasting/painting cycles, etc.
Acid surface pre-treatment for corroded steel surfaces have shown limited advantage in relieving the problem.
Removal of the rust is extremely difficult under temperature, concentration and application conditions of the field.
Also in many situations, residual acids or salts left in the pores of the rust have caused failure by osmotic blistering of the paint system.
Even under the best field conditions, the use of conventional phosphoric acid based pre-treatment is also unsatisfactory.
Such products do not accomplish a true passivation of the metal surface, and their reaction with the different rust layers is not homogeneous and inefficient.