Stewart Systems EkoPoxy Primer/Sealer is a high quality water based Epoxy primer for use on many substrates. Stewart Systems EkoPoxy can be used on interior and exterior surfaces where there is more chance of corrosion from the environment. Excellent adhesion to bare metals, resists flash rusting which can occur with latex based primers. Stewart Systems EkoPoxy has superior chemical resistance, is fast drying and mar resistant. Stewart Systems EkoPoxy is low in VOCs and compatible with a wide range of top coats including EkoPoly Top coat. Nonhazardous, nonflammable and water cleanup, Stewart Systems EkoPoxy is your best choice for Primer.
I have used this on my last project and like it very much.
I have previously been using a self etch zinc phosphate primer, and now that temperatures are warm enough, I have switched to using EkoPoxy. It is way less pungent (my etch primer stinks days after application) and seems to apply well (I am using it as a primer on interior components. Appears to adhere better than the etch primer (doesnt marr readily when riveting), and can be applied with a small touch up gun (0.5mm nozzle) if you add more water (+50%) to thin it (although the manufacturer recommends only applying with a 1.5-1.8mm nozzle). Only time will tell its true corrosion resisting potential. All said, Im very impressed, and its so nice not to have pungent VOCs around you the whole time (but still wear good respiratory equipment).
Per the supplier: It is compatible, but the surface must be prepared properly, and be sure the existing primer was properly applied.