the shop i blast for uses CRE, its a heavy/fill type epoxy primer,,, sands pretty good with 180, and fills pitted areas very well. good for frames, and suspention parts etc,,
i used this for the first time on this 37 packard frame,, its nice

you can fill/spray up to 3-4 coats, (3:1:1) back to back, on heavily pitted areas, wait till it drys, sand 180, shoot base, chassis coat black,

or cut it with zylene (3:1:1.5)to matte the cre down, respray as final coat. Also lacquer will flatten it out, he told me.. i ve got pics somewhere.. i am really happy with results,,

the shop uses the slicksand also... i think spray up to 2mm-3mm? if i remember, then block, block..