Yay! Much Better!
I had to zoom into the reference and paint over it in order to understand it best. As well as paint the mortar as though it was individual pieces.
There are a few layers here…
1: Basic forms, the large stones, and the tinier stones for the cracked mortar
2: The lighting values for the above forms (light from the top left)
3: Underneath those, is the darkened layer for the cracks, which also hold light information
3.5: I then painted in some basic cracks with the dark value, and then added the light value.
4: I then tried to duplicate some of the texture information using photoshop filters, sponge painting and angled strokes.
5: I finished it with (or tried to) some water painted edges on the bigger stones. I’ll get this better next time.
I think the most important tip I can say to use is… Black for your dark value, and white for your light value, both with a soft light blend mode. No matter than color you’re using underneath. This way, no matter what color you use, it will look good. This also gives you the flexibility to change it later. Really I wonder if the whole process could be done in black and white and change the colors later… or if this would look totally washed out since green next to red makes it pop out.
Another thing is to use photoshop smart objects before you apply your filters. In ps cc, if you convert your layer to a smart object, and then apply the filter, you can edit the filter later. Yay more non-destructive workflows!
Great! Happy Handpainting! Now… Someone turn this workflow into a tileable texture… Oh wait, that’s me! …And for attempt 3…or 5 if I want to try more things.