I started the second coat of concrete on top. I had to make it level, first of all, then begin forming the bark around the edges. I had several pieces of oak firewood for reference. There is a sharp contrast between the dark bark and the heart of the tree.
I then began going down the sides. I brushed the acrylic latex compound onto the scored cement first, then began laying on the second coat. I had to use a trowel and press it on; otherwise, it would just fall of the side onto the table. I used clay-sculpting tools to make the furrows, followed by a wet brush.
You can see the first layer of scored concrete on the right, with the furrowed bark on the left. When I had done this much of it, I wrapped the stump with plastic until I come back to layer the rest of the bark. Real bark would be rougher than this. I have brushed the concrete smoother, since bark would compress or crumble, if rubbed, but rough cement would just feel prickly. It seems to me that a rough concrete piece would be undesirable. It may also be difficult to stain.