Textured concrete methods

Hello R/concrete

I'm struggling to get the right texture on my mold casts.

(Disregarding colour) I'm trying to get a sandstone texture on my casts alike in this picture. But I've tried a few in-cast coating of sand etc, but they made the concrete worse, and didn't allow me to compact it very well.

I'm thinking of using washing techniques, alike when you want exposed clean aggregates on a wall. But I have little experience with a washed concrete cover. I'd do this after removal from the mold. There is always at least one side not covered so I can just lather it on as desired whilst it is stable.

Textured molds are possible, but not preferred (due to construction costs)

Does anyone have any experience or tips?