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  • Writer's pictureheykiddoco

How to use Jesmonite to create terrazzo

Exploding in popularity, Jesmonite has become a go-to material for creating a variety of stunning surface designs such as block colour, ombre, marbled and terrazzo. If you're unfamiliar with terrazzo, you can read my post What Is Terrazzo? to understand the basics behind this surface pattern design.

To create terrazzo home accessories, I use Jesmonite AC100. Jesmonite AC100 is incredibly versatile and can by pigmented to almost any colour - making it an ideal material to use for creating terrazzo chips. Jesmonite AC100 cures within 20-30 minutes so I recommend starting with smaller volumes of the material and working your way up to larger quantities until you're comfortable with the process.

To make a terrazzo piece, we first need to create the terrazzo aggregate or "chips". This is done by pouring out thin layers of Jesmonite onto a sheet of plastic (or similar), allowing the layer to fully dry, then crunching it up to smaller pieces and finally combining the aggregate back into the Jesmonite mixture.

I start by pigmenting the Jesmonite AC100 liquid to my desired colour. It's easier to pigment before adding powder as this is a time-sensitive process. Once the liquid and powder are combined, the clock starts ticking as their chemical reaction begins bonding. It's important to note that once the gypsum powder is added, the colour may change slightly.

Once fully mixed, I pour out the pigmented mixture onto a thick sheet of plastic (or similar), using a wooden stick or spatula to spread the Jesmonite out into a thin layer.

Spreading Jesmonite into thin layers makes it easier to to crunch up into smaller pieces. I usually use a hammer and a repurposed poppadum tub to crunch up my pieces.

A close up of terrazzo aggregate, colourful shards in shades of mint green, orange, pink, peach and yellow

Once reduced to the desired size, I mix another batch of Jesmonite, taking the terrazzo aggregate and combining it into the mixture. This is then casted into my silicone moulds, where I leave it to dry and cure overnight.

I leave the mixture to fully cure before demoulding. Jesmonite sets after around 20-30 minutes, though it is recommended to leave it in the mould for 2 hours then remove it and leave to fully cure for a further 24 hours. This allows the chemical reaction to fully bond.

It may not look like much when removing your casted piece from the mould - this is where the magic of sanding comes in! Sanding back layers and layers of Jesmonite will reveal the terrazzo pattern beneath the surface.

Circular trinket dish split diagonally in two. One side is plain white and unsanded, the other side is sanded revealing a terrazzo pattern.
Before-and-after sanding to reveal the terrazzo pattern

Terrazzo is an invested process that requires several steps (including a lot of manual labour) to create the pattern. Each pattern is completely unique every time and results in some incredible designs.



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