Rocks and rubble for 28mm terrain

For one of my terrain projects (a ruined roman villa) I needed a large amount to brick building rubble.  There are commercial scale model bricks available but they are much too expensive for the amount of rubble that I would need.  I remembered that left over plaster of paris when broken up looked a bit rock like so I decided to do some trials.

I mixed up some plaster of paris and then spread it very thinly on some plastic takeaway lids.  Once dry I could easily break off the plaster and smash it up to for rubble.  My wife then mentioned that most of the rubble (for the roman villa) would be brick, not white plaster.  So I made some more plaster of paris and did a trial colouring it.  First I tried inks but they didn't really get the colour dark enough and I didn't want to use any more of the expensive inks to try.  So I swapped to cheap acrylic craft paint and mixed some of that in.  A key thing to remember is that the plaster is white so it's like mixing in with white paint.  Once I had the colour I wanted (a red/brown brick like colour) I spread out the plaster as usual and waited for it to dry.  Plaster of paris normally takes approx 1 hour to dry.  The plaster with the paint took 12+ hours to dry.  However the wait was worth it as now I had a pile of brick rubble and plaster rubble.

Plain white and brick colour rubble

On a "don't try this at home" note don't break up the plaster on a wooden bench with a hammer.  You end up with plaster rubble and a nicely dimpled bench top.  This was even with the plaster wrapped in a rag to cushion the bench top.  Better to use a sacrificial lump of wood or plastic chopping board underneath.