I recreated the tar substance while adding in some extra features of my own...
I made everything more interconnected. While fiddling around with the effects, I noticed that things look more realistic and natural when they were more interconnected. For example, the bubbles would be affected by the overall flow of the tar, stretching along with it slightly. However the overall flow would also be influenced by the bubbles -- the folds would be pushed out by a bubble perhaps. The interactivity of these effects meant that I would have nodes being connected from all over the place. To adjust to this I had to change up my organization a bit. A brick wall substance you could have the stone material, mortar material, and moss material, each with their own masks cleanly separated. Aaand of course this ends up in a disgusting node web.
However in this graph every effect connects to every other effect, resulting in a nasty web of a graph. So I decided to keep each effect in their own frame, vertically. Then when I implemented each effect with a blend node, that was spaced horizontally. In the end I had clear diagonal connections and vertical connections. The diagonal connections trace back to the effect, and the vertical connections are where each effect was influenced by another separate effect.
I added obstacles for the tar to flow around. In this case it was some boulders, perhaps a tar spill near a mountainous construction site. I liked the idea of using flow to suggest a liquid feeling to the substance, but if it was a large patch of tar the flow looked a little arbitrary. I chose to add some obstacles so the flow pattern might emerge as more natural and understandable.
I also included some wet tar, along with more the more aged tar that has a "skin" with folds in it. The wet tar is more reflective, active with more numerous but smaller bubbles. I liked that the contrast it provides so that you also get a sense of activity/change with a time aspect to the material.
An early iteration without the rocks (shows the wet tar a bit better):
Replies
An early iteration without the rocks (shows the wet tar a bit better):
The reference:
See some more variations, info about the reference, and the substance graph overview here.