There are loads of tutorials online for making concrete letters, but most of the letters are made out of cement rather than concrete. (Cement is an ingredient of concrete.)
While we wanted to use concrete, we didn’t want to use quick-setting concrete because we wanted a smooth and even finish. So, we decided we would achieve a finer consistency by mixing the concrete ourselves. Another reason we chose to mix our own concrete was so we could work at a comfortable speed and take our time getting it into the molds before it started setting up.
After a bit of experimenting, we came up with the following project.
Tools & Materials List:
- Mask and gloves (You should always wear protection when working with concrete, as you don’t want to inhale any toxic concrete dust.)
- Letter molds (We used cardboard letters, also called “papier-mâché” letters.)
- Craft knife
- Sand (We used children’s play sand because it’s extremely fine.)
- Sieve, optional
- Concrete plasticizer additive (This enables you to put less water in the mixture. The more water you have in the mixture, the more it will shrink.)
- PVA glue
- Sandpaper, optional
1. Prepare the molds by carefully cutting away the backs of the letters using a craft knife, and then removing anything inside.
2. Put on a mask and gloves. Spray the inside of the molds with WD-40 to help keep the concrete from sticking to them.
3. Continuing to wear the mask and gloves, weigh out the ingredients as precisely as possible. The ratio of sand to cement should be 60 percent to 40 percent. Then add plasticizer (2 percent), PVA glue (2 percent), and water.
Start by combining the sand and cement. We sieved the cement to make sure the mixture was free of lumps.
In a separate container, combine the plasticizer, PVA, and some water.
Combine the two mixtures, adding more water as needed, and mix well.
You want the mixture to be quite stiff and not too sloppy. The plasticizer allows you to use less water than would normally be necessary. If the mixture is too sloppy, it’ll soften the cardboard letters, and the mold will warp.
4.Spray the molds again with WD-40.
5. Using a trowel, fill the first mold with the concrete mixture, making sure to pack it tightly and get it into all of the corners. When the mold is about half full, tap it on a hard surface to remove any air bubbles and to make sure the mixture is distributed evenly. Continue adding more concrete mixture until the mold is full. Then use the trowel to smooth the surface. Repeat with remaining molds.
6. The concrete needs to be shaken well to remove any air bubbles. Since we don’t have a professional concrete-vibrating tool, we put the molds on the washing machine during the spin cycle. It sounds bonkers, but it works!
7. Let the molds set, undisturbed, for at least 48 hours; 60 hours is ideal. Don’t touch them, or the concrete will crack. After 48 to 60 hours, peel away the cardboard molds. (The WD-40 should help the cardboard come off easily, but if not, wet the cardboard molds to soften them, and then peel them off.)
8. If you want a smooth texture on your concrete bookends, sand them. Otherwise, leave them as-is.
This project is courtesy of Christine and Jan, ©Little House on the Corner.