What is Phosphate?

Phosphate is a type of conversion coating used to produce a heavily crystalline structure on steel parts. This coating provides improved resistance to wear and when coupled with a Chromic Dip and Oiling process will also improve the corrosion protection of the parts. Like other conversion coatings this is a chemical process and is a good pretreatment for paint. Both coatings, as supplied by Anoplate, have a dark grey appearance prior to any oiling.  

What Specification is most commonly used? 

While Anoplate is NADCAP Accredited for MIL-DTL-16232, AMS 2481, & TT-C-490 we most commonly see demand for the MIL-DTL-16232 specification. 

There are 2 types of Phosphate commonly used, both of which are available here at Anoplate. 

  1. Manganese Phosphate – The harder of the two coatings. This is used to improve wear resistance, corrosion resistance, and lubricity for steel parts in a variety of applications. Manganese Phosphate (Type M) has a minimum coating weight of 16 g/m^2, making it the “heavier” of the two coatings as well. 
  2. Zinc Phosphate – Lighter and softer than Type M, Type Z is generally used more as a pretreatment for paints to help promote adhesion as well as to prevent rust. Minimum coating weight for Type Z is 11 g/m^2. 


Some common industries that use Phosphate; 

  • Aerospace 
  • Defense 
  • Firearms 
  • Automotive 
  • Commercial 


If you have any questions about this or any other service we offer, please contact us today!