Ask the Expert Question-and-Answer Archive

by Ron Joseph

July, 2008

Which Wash Primer to Use?

Q: I'm not clear on the difference between MIL-C-8514 and DOD-P-15328 Wash Primers. Which is the preferred to use? What are the benefits/drawbacks of each?

Attached is MIL-C-8514C with Amend 1. This specification is listed as still current. I am finding GSA provided Military products indicating that they are compliant with either MIL-C-8514C or DOD-P-15328. My challenge is to pick the best/correct product for our application which is to apply a Wash Primer after blasting to Military trailers. Both are being referred to to as 'metal pretreatment coating compounds'. I appreciate your assistance in this matter.

A: The two wash primers look very similar to each other and I cannot discern a difference unless I spend more time comparing the ingredients and their respective percentages. MIL-C-8514C is intended for aircraft metal; namely predominantly aluminum alloys, whereas DOD-P-15328 is predominantly used on steels. It is possible that MIL-C-8514C contains less acid to insure that when it is applied to aluminum one does not have excess unreacted acid remaining on the surface. When I worked for a military contractor I always recommended that when DOD-P-15328 was applied to aluminum the painters were to dilute the wash primer with alcohol to reduce the acid concentration.

Hence my recommendation is as follows:
For aluminum surfaces apply MIL-P-8514C; for steel surfaces apply DOD-P-15328. I urge you to call the paint suppliers form whom you intend to purchase the coatings and ask the chemist in the laboratory to confirm this or to offer another recommendation.

Regards,

Ron Joseph