HEAVY PHOSPHATE COATINGS

Parkerising is the treatment of iron and steel by immersion in an aqueous solution to form a heavy phosphate coating. In this case heavy means to Def. Class 1 or 2 Process or as defined by BS.3189 Class A1 or A2, and includes iron, zinc and manganese phosphate processes, such as Parker F, Parker 30 and Parker 85. The treatment is a two‐stage process, the first being the actual phosphate treatment and the second the sealing coat. The processes are so designed as to give an absorbent surface which is capable of retaining the subsequent finish to enhance the corrosion resistance.