The diorama base is a piece of 50mm thick blue foam insulation board approximately 150mm square. Unfortunately I had already carved it to a rough shape and applied plaster of paris to form the basis of the rocks before I decided to do this blog and hadn't taken any photographs.
The base was first given a coat of neat pva glue and plaster of paris was mixed with water and a dark grey acrylic paint to form a stiff mix. With the glue still wet the plaster of paris was them liberally trowelled into place with a palette knife and roughly shaped. Once the plaster of paris was nearly set. the rocks were smoothed by rubbing over with a wet finger. They were then left to dry thoroughly for 3 days.
Some shrinking aand cracking is inevitable but this can be used to advantage.
The cracks can be scraped with a sharp pointed tool such as a bradawl or in my case one of our meat scewers (shhhh! don't tell the wife) to form fissures, work in progress below.
When happy with it the whole rockface was given a coat of dark grey, almost black, making sure this got deep into the fissures and cracks. The rocks were then painted with a number of different shades of grey some with a touch of burnt umber to give an earthy tone. Finally they were given a dry brushing with a very light almost white shade to highlight and sharp edges and bumps.
Next job will be to add the static grass.