Friday, 31 August 2012

Making textured plaster plaques for a scenic base

It's time to make a scenic base for my Pie Clown. Rather than using any pre-made moulds or ready cast pieces I decided to make my plaster scenery from scratch. I've always rather liked using plaster to create scenic bases as It's lightweight, relatively strong and very easy to carve. It is also very fast to work with. Both the pieces for this base took under an hour to texture up starting from the blank plaques. 

First of all I needed to cast up a couple of blank plaster plaques to fit onto the resin plinth I had chosen. One will form the pavement the other a wall.

I began by rolling out some plasticine to an even thickness. To do this I used a couple of pieces of balsa wood and a wooden dowel. While it isn't essential to have the plasticine all of an even thickness it does help to achieve a better result.

Using a straight edge and a scalpel (or craft knife) I cut the plasticine into four strips.

Using a piece of plasticard as a base and my plinth as a guide. I built a mold using the plasticine strips. Place the cut edges of the plasticine against the sides of the plinth one at a time and gently press them into place. 

When all four sides are done make sure the corners are sealed and then carefully remove the plinth.

Mix up your plaster as per the instructions and (on a level surface) carefully pour into the mold to the required thickness.

Once the plaster has set (be patient & dont poke it!) carefully peel away the plasticine and the plaster plaque should pop free of the plasticard. Now let the plaster dry out over night. Depending on the thickness set plaster can take a long time to fully dry out. Although you can carve it when slightly damp I'd recommend that you make sure it's fully dry before you do any gluing or painting.

The plaster plaque probably won't be perfect so carefully sand the edges to remove any flash. I then began to inscribe a brick pattern onto the plaster using a pointed stylus (in this case a piece of brass wire filed to a blunt point).

With the basic brick pattern inscribed I then added some texture and damage using a variety of tools. A stiff paintbrush is particularly useful for softening out some of the hard edges. To get an overall rough texture I placed a piece of course sandpaper rough side against the plaster and burnished it. The texture was then impressed into the plaster. I used a stone out of the garden as a texture stamp  to create some random looking chips and dents. 

It's well worth casting up a few spare plaques and trying out a variety of tools and techniques as a wide variety of finishes could be easily created.

Working with plaster can be a very messy business and sanding/carving plaster will create a lot of dust. Don't forget to follow all the usual safety precautions to protect your eyes and lungs.


  1. Hi David, can you explain the burnishing with the sandpaper? I dont understand what you do to get that wonderful texture

    1. Take a sheet of course sandpaper and place it with the rough side against your plaster. Now rub the smooth backing of the sandpaper with a burnishing tool - press hard in a circular motion. The back of a teaspoon will work as a burnishing tool in this instance. By burnishing the back of the sandpaper you are pressing the rough side into the plaster and making an impression of it's texture. Now peel off the sandpaper and clean away any loose material from the plaster with a soft brush.