Make Cement Terrazzo With Leftover Resin

Terrazzo objects made with colourful chips are traditionally made using jesmonite, but I'm going to show you how to fake it and use resin instead. It's a fun project for people who work with casting resin a lot and want to utilize ANY leftovers.

I've been doing a lot of projects involving casting and every time I mix a new batch of resin, I have to mix 5-10% more than needed just to be on a safe side. In the end, I have a small amount left in the cup and absolutely nothing do with it. I started adding pigments to these leftover mixtures, pouring them out onto a flat surface and letting them cure. I've been collecting them for weeks and finally have enough to use in this project.

• Resin and pigments (polyurethane or epoxy resin)
• Small sheet of cellophane
• Disposable cups and stirrers
• Kitchen scale
• Cutting pliers, hammer (optional, depends on the thickness of resin)

• Plastic or sillicone mould
• Glue gun (optional)
• Lubricant
• White or grey cement
• Cement pigments (optional)

• Sanding paper (various coarseness)
• Spray-on gloss varnish

Measure part A and part B in separate containers, add them together and colour the mixture. Pour the resin onto a sheet of cellophane and spread it out to 2-4 mm thickness. Don't pour it onto wrinkled plastic sheet or clingfilm, because the end result won't be smooth (see pic 3, resin poured over clingfilm)

Once resin is cured you can crumble it into smaller pieces. I used a hammer for some of the resin pieces, some of them were too thin for a hammer and I had to use cutting pliers and/or crumble them by hand. I made the pieces on a small side because my tray had a very thin lip and I wanted to make sure they will be able to access all tight spaces.

My moulds were 3d printed and needed some clean up before I could proceed. Pentagon moulds had to be glued to a flat surface with a glue gun since I printed them without a bottom.

I used WD-40 and a brush to lubricate my moulds.

I used water to measure the volume of each mould in order to prepare correct amount of cement and correct amount of resin chips. I used a ratio of 5 parts mixed cement to 1 part resin chips.

I mixed dry, grey cement with black pigment and added just enough water to create a thick paste. I then added my resin chips, mixed it really well and poured half into the mould. I had to pound and drop the mould onto the countertop a few times to make sure all air bubbles raised to the surface and cement mixture got into all those tight spaces. Added more cement and used a plastic ruler to smooth and level out the surface. I left it to dry for 12 hours before I unmoulded it.

I did the same with pentagon coasters, except I used white cement.

Before you unmould, use a craft knife and very coarse sanding paper to level the back of the tray. It will be easier to do it at this point because you will have the mould walls to guide you. Gently unmould in case not all parts are dry yet and, if needed, leave it to dry further for a few hours.

At this point terrazzo chips won't be visible, your objects will look like they are just solid cement.

Use a combination of different sanding paper grits (40-240) to reveal resin chips. Seal with a spray-on varnish.