I have had great results/utilizing the Self-etching primer. The adhesion to cast iron has never been a problem for me, so I’m sticking to what I know works.

I recommend this product specifically, but also ask if anyone has tried painting vises utilizing the ‘Automotive Primer,’ also by rust-oleum?

I have not, but was curious!
I concur. Been using Duplicolor Self Etching primer with excellent success for 5 years. From what I read, DC makes the primer for Rustoleum.
The zinc green is very light, similar to gray. As always , prep is key on vises; as you know, every nook and cranny needs scrubbing/degreased.
I put on one coat, as lightly as possible. Special attention to hitting the hard to reach spots first.
Wait 30 minutes or a tad more for it to dry, then topcoat. I try and use Duplicolor Ceramic engine aerosols exclusively: Outstanding paint.
I also have excellent results with all of Rustoleum’s Stop Rust aerosols, including their textured line. Krylon Max two in one is excellent as well, but YOU MUST put a primer underneath all of the two in one ( primer-paints in one) or the results will be less than optimal.
I did a test portion on my gray Rock Island with just the Krylon Gray…It was GHASTLY without primer. I regrouped, primed according, and the gray looks and acts like powder coat.
I did my 542-BX in a gray, and my buddies in Detroit Diesel Alpine green. Baked them in the summer sun for four hours and they look incredible. The reason I favor engine enamel is it’s designed for cast iron surfaces, and our vintage vises are obviously cast iron/steel.
The texture and every little mark shows nicely under engine enamel, plus, the final sheen looks very clean and industrial, not over the top like a vintage car restoration…I don’t enjoy my vintage tools looking “over done” or too nice.
I appreciate anyone willing to do this to their own stuff, and still admire their dedication and skill, but this type of look is not me.
Here are the two 542-BXs.
A few days ago I did a nose cap for my 1952 Dewalt GR radial arm saw in the Detroit Alpine Green (under Duplicolor self etching primer) as a test.
About 12 minutes of time primering/topcoating with a sun bake and it looks like it was done in a booth, not my driveway…Also, SEM makes an excellent ( reasonably priced as well) self etch aerosol in satin black.
Keep up the good work everyone!