Looks like I'm going to have a white sink. I am using 1 part epoxy paint (for garage floors) over the primer. I thought from the description that the paint was a grey color, but it's pretty clear in actual use. I do wonder if I should do a top coat of a flat grey...
I found this thread searching darkroom sinks, thanks for all the great information and first person accounts! I found Joe DeMaio et al book available to download https://epdf.pub/the-new-darkroom-handbook.html