DERUSTING AND RUST-PREVENTIVE AGENT AND METHOD OF DERUSTING WITH THE SAME

摘要

The invention aims at derusting rusty metal articles completely only by immersing the articles in one solution (a derusting and rust-preventive agent) or applying the solution to the rust on the surfaces of the articles and enabling the resulting derusted metal articles to dispense with after-treatment such as washing; at enabling derusted metal articles to exert rustproofness for a long period both in doors and out of doors only by subjecting metal articles taken out of a derusting and rust-preventive agent to spontaneous drying or wiping without water washing; and at enabling one solution to exert two functions, i.e., derusting and rust-preventive functions. The invention relates to a derusting and rust-preventive agent which contains about 50 to 600g of orthophosphoric acid and about 0.2 to 2g of DL-malic acid per kilogram of the agent with the balance being water. A rusty metal article is derusted with the agent and spontaneously dried or wiped, whereby a phosphate coat is formed on the surface of the article to exert a rust-preventive effect.