Lime-Based Decorative Powdered Plaster For Exteriors Powderstone is a natural, lime-based plaster that is sold in a powder form. It's one of our most practical materials, as it offers a breathable, rich application with only a single coat. Despite the thickness of the material, it still maintains a great level of flexibility, ensuring a considerable resistance to cracking. It's ideal for highly textured, earthy finishes, as well as simple semi-smooth applications. It can also be covered using different metallic paints or colour washes, to achieve different decorative finishes.