I am planning to replicate rough-cast rendered walls on a 1/152-scale church. My first thought is to coat the surface with PVA glue, followed by an overall sprinkling of sharp sand. Once completely dry, any excess can be shaken off, and the surface primed and painted. An alternative is to use chinchilla sand, which has a much finer grain.
I would be interested to hear of any other suggestions ... maybe you have attempted a similar treatment.

Hi Paul

Perhaps a suitable grit sandpaper would do the trick?

Cheers

Chris

Yes, I have considered that option ... often used it to depict rendered walls on battle damaged buildings (and tarmac or concrete ground surfaces). However, this is not the best choice here, as the complex shapes would make it difficult to apply without ending up with noticeable seams (even after painting and weathering).
Of course, I could simply build the church using pre-textured plastic sheet, but again the joins would be difficult to conceal.
I am sure that some type of sand (sprinkled over a glued surface) is the best approach ... similar to the way non-slip surfaces are replicated on 1/35-scale modern tanks.

If you have trouble finding sand fine enough for your purpose, you might want to look at rock tumbling grit; it comes in various grit sizes (the higher the grit number, the finer the grit, just like sandpaper), so you should be able to find a grit that would give you the amount of texture that you want.

Thanks for that information ... I was aware of such a material (and its use), but never knew its actual name.