With the papier-mache layers completed, the next step was to cover the structure with a layer of emulsion paint.
The point of this layer is to protect the underlying papier-mache structure from mold formation. The emulsion coat protects the underlying paper from moisture. We also used a wallpaper paste which contained some fungicide as additional protection against this.
Of course, emulsion paint also provides a cheap alternative to acrylic paints. It is much thicker and cannot really be used to paint detailed areas, but for large spaces like the walls of a building it is ideal. We used Dulux Almond White for the building, which gives it a slightly off-white colour. All that remains to be done is a little touching up with some acrylic paints, and perhaps some Devlan Mud to give the place a lived-in look.
Here is a view of the water-tank after painting.
The base was then covered with a layer of Cuprinol Garden Shades fence paint. This initially provided a layer that was not very smooth, and difficult to paint over with ordinary acrylic paint.
However, since the base will eventually be covered with a layer of fine sand to give it texture, this is not really a problem, as the overlying sand will then be painted and drybrushed to give the final effect.