Sanding is the most involved part of working with Jesmonite. It's manually intensive, time consuming and often requires multiple grades of sandpaper grit. However, do you always need to sand the items you make with Jesmonite?
No, you don't always need to sand Jesmonite
Depending on what visual style you're making, you may not always need to sand Jesmonite. Terrazzo is one of the most popular applications for Jesmonite. The process for making terrazzo generally requires sanding in order to reveal the terrazzo patterns beneath the surface.
If you are working with block colours, ombre or marbled designs you may not need to sand your cast at all!
However, if your cast has sharp edges or an uneven base, you may wish to lightly sand the surface to make it level or safer to handle.
Why do we sand Jesmonite?
There are multiple reasons to sand Jesmonite. When working with terrazzo patterns, it is primarily to reveal designs or inserts beneath the surface. When the cast is first removed from the mould, it looks relatively plain. However, sanding back layers of Jesmonite will remove the surface layer to reveal the aggregate inside.
For any casts that don't contain an aggregate, it is not necessary to sand them unless you want to alter the surface.
Surface texture
Sanding can help provide different surface textures. Working with coarser sandpapers wil
l create a rougher surface, whereas finer sandpapers will provide a smoother surface.
Depending on the texture you want to achieve, you may wish to create a rough, textured surface or a smooth, polished surface.
Altering the shape
Sanding a surface can lead to altering the shape. When sanding Jesmonite, we are removing layers of the material. This can be beneficial if we have an uneven surface; sanding can help to flatten the area.
Additionally, if you overfilled your mould you can sand it back to the correct dimensions.
Always be cautious when sanding not to alter the shape too much. Applying too much pressure can easily cause dents and undulated surfaces.
Removing hard edges
In the majority of cases, when Jesmonite is removed from the mould it will have a fairly sharp edge where the material meets the mould. These can be very easily sanded away with a finer grit sandpaper and help make your casts safer to handle.
As a terrazzo artist, sanding is a primary part of my process. You can see the work I produce and purchase my products on Etsy @HeyKiddoUK.