Thanks grover26! Can you attest to it never hardening and staying black? Did you prime at all?
I will attempt to recall my Coal-Tar Epoxy experience from four decades ago, which is at times, at my age, is easier than to recall four hours ago...lol: It was recommended to me by a friend who did underground tank installations. I had no prior knowledge of the product. I don't recall the manufacturer, but it wasn't one of the popular paint companies. It was a marine grade product. I applied by spray using a Binks #7 gun. A pressure feed gun may have been a better choice, as I wasn't able to get much of a pattern. As stated, metal was freshly sand blasted. I applied per manufacturers instruction of no primer...direct to metal. I don't recall any softness to the coating once cured...actually very hard. I can attest to it's hardness as I got some in my hair which the only solution was the cutting out of some clumps. Over time the rich black color did turn more of a dark gray (Hot Rod) primer color, but protection was never compromised. It took a number of years for the color to fade, as any 'paint' would in time. If appearance is a concern, a top coat of enamel or urethane could be applied.
My thoughts: Being it's still around in this age of 'miracle' coatings it must work. After all, it is an epoxy, which along with urethane, is the base of most of today's auto primers and top coats. This was my only experience using Coal-Tar Epoxy. Key to my success may be that it was a marine grade coating made for salt water exposure. If I can be of further help please feel free to write.