by Yun-Han Lin
Terrazzo is commonly used in traditional wall and floor treatments in Taiwan. In recent years, there have been changes in colors in this composite material from Italy used in modern architecture. We have studied the traditional approach for using terrazzo surfaces and come up with the versions suitable for hand-made small objects!
The traditional ways
- Terrazzo: composite material where the matrix of chips of marbles are poured with a cementitious binder. The cement and pebbles on the surface are ground, waxed, and polished using a polisher after drying. The surface is flat and smooth which come in irregular patterns. Commonly used for indoor floors.
- Pebble dashing with a rustic finish: a type of terrazzo topping where the matrix is applied evenly to the floor or wall. Upon drying up to 70%, the cement is wiped off a bit with a sponge, so as to expose the tips of the pebbles without destroying the bond between pebbles and matrix. Commonly used for outdoor floors, walls, and slopes.
- Pebble dashing with a wash finish: similar to that with a rustic finish, while the matrix is recessed by washing. More matrix is washed away, and the pebbles are exposed almost entirely. the surface is basically formed by densely applied pebbles upon completion. Commonly used for outdoor floors and slopes.
- Terrazzo with surface cutting: the surface is cut and scratched with all kinds of choppers after drying, so as to form long cut marks. This method is the most labor-intensive and time-consuming among the four.
Terrazzo made of cement
With reference to both the traditional methods and innovative ones on the Internet, we decided to use cement and concrete pigment by Lotos to imitate the colorful terrazzo that has been quite popular in recent years.
Material: white cement and concrete pigment by Lotos; silicone mold; mixing container; mixing rod, water, plastic bag
- Step 1. Silicone molds
We wanted to make a calf-shaped mold, which is about the size of a coaster. Silicone molds can be bought from the Internet. Terrazzo topping usually requires a larger surface for grinding, so the size of the project is recommended to be at least as big as a coaster.
- Step 2. Colored cement pieces
Place a piece of plastic on the table, and pour the mixed colored cement on the plastic. After drying, you will have a whole piece of cement in an irregular shape. Break it into small pieces randomly. The color and darkness can be customized through the mixture.
- Step 3. Molding
Mix a bowl of white cement and pour it into the silicone mold with the colored cement pieces. Wait for it to dry before demolding. We tried the series of steps in 3 different ways and the finished product all ended up different. The following are the details for your reference.
1. Mix the colored cement pieces into the white cement and pour the mixture into the silicone mold all at once. After demolding, the colored pieces will end up at the on the bottom of the mold, and the whole pattern appears more random, which makes it harder to place the colored pieces as intended.
2. Soak the colored pieces in water first, so as to squeeze out the air bubbles in the pieces. Next, place them on the bottom of the silicone mold where you prefer. Pour the white cement gently into the mold, or the colored pieces will be washed away from the positions intended. The colored pieces will end up at the the bottom of the mold.
3. Pour the white cement mixture into the mold first. Place the colored pieces, after soaking them in the water, on the mixture and press them gently to the level where they are aligned with the surface. In this way, it is easier to control the positions of the colored pieces. Yet, the surface can be uneven after demolding, so it takes more time to grind the surface afterwards.
- Step 4. Grinding:
Grind the white cement on the surface with the color pattern by 0.5 ~ 2mm, so that the color pieces can be exposed.