Month: February 2022

The excavation at an ancient Roman fort in Germany in the 1940s shows how far back coating metals with phosphates goes. Several iron items were found in remarkably good condition, with their surfaces converted into a blue iron phosphate coating that resisted corrosion remarkably well over the millennia. The widespread use of phosphate coatings in modern society did not begin until the mid-19th century, however, with the discovery that hot iron treated with coal dust and potassium phosphate resisted corrosion. From 1869, a variety of methods for coating metals with phosphates to protect iron and steel from corrosion were patented, and the process became increasingly widespread. Zinc and manganese phosphate coatings – the two most common types of phosphate coatings – are now widely used for a number of industrial purposes. Continue Reading