The reactive rust remover from Koch Chemie, 500 ml, is a neutral pH agent that removes surface rust and metal particles, including plaque dust. Gentle with all types of materials. The ingredients are coordinated to allow contact and soaking for an extended period, so that the reactive agents in the reactive rust remover from Koch Chemie efficiently dissolve dirt and rust particles. The reactive rust remover from Koch Chemie, 500 ml, changes color to purple once it begins to dissolve contaminants. The surfactants in the formulation work to coat and dissolve dirt for easier rinsing later. Instructions for use: for painted surfaces, glass, and car rims, including commercial vehicles. Check sensitive surfaces such as polished aluminum before use. Apply undiluted to the targeted surface and leave it to absorb for three to six minutes. If necessary, agitate with a brush or sponge. Rinse thoroughly.