Ask the Expert Question-and-Answer Archive

by Ron Joseph

November, 2004

Repairing MIL-PRF-22750 Epoxy Before Applying MIL-PRF-85285 Topcoat

Q. We painted some aluminum and composite items with the correct primer MIL-PRF-23377 and the wrong paint MIL-PRF-22750. What kind of surface preperation is necessary prior to repainting with the correct paint MIL-PRF-85285? What is the difference between MIL-PRF-85285 and MIL-C-852885?

If the epoxy MIL-PRF-22750 is still quite fresh, you should be able to apply the MIL-PRF-85285 directly over it without any surface prep. However, if the MIL-PRF-22750 has already started to age, or if is has been exposed to sunlight, I would scuff sand the entire area, wash it off with fresh water, and then apply the MIL-PRF-85285. You can even consider perfoming performing a solvent wipe with MEK, or MEK/Acetone (50%/50%) over the areas before applying the topcoat. However, before proceeding I would conduct a slew of adhesion tests on some hidden areas to insure that the intercoat adhesion is good. THIS IS YOUR To the best of my knowledge there is a difference between MIL-PRF-85285 and MIL-C-85285.

Best wishes,

Ron Joseph