Here are some key tips for making your own concrete Spheres! One of the most popular items at History Stones are the Sphere Molds. Especially with spring coming! Making your own concrete spheres is a great beginner project for so many people. Especially those who do not want to spend a fortune on finished spheres! From mixing the concrete to pouring you will spend less than 20 minutes on this project. ( The hardest part is waiting 24 hrs for the concrete to cure .)
Selecting your sizes:
These things can be heavy!! History Stones offers thee different sizes for our sphere molds 10″, 12″ and 15″ diameter.
Here are the finished weights for each size:
10″ 35 lbs
12″ 45 lbs
15″ 75 lbs
Tip: You can cut the weight by positioning a smaller mold in the center. This photo below shows the 12″ sphere in the 15″ sphere to create a hollow center.
A large plastic bucket is a great example for something you can use to stabilize your project. You can absolutely use anything else you have around the house to keep your sphere stable, just make sure that your sphere is not leaning to one side more than the other. ( This will keep your project level, so the two sides fit together nicely. )
Twist the inside mold 1 hr. after you pour.
About 1-2 hours after you pour your . Swivel or turn the inside sphere so that it is easier to take out once the concrete has hardened. Although you will use a release agent (any brand of cooking spray will work great!) the outside of the sphere mold has a texture that will grab onto the concrete. Every other piece will just pop right out. You can make the un-molding process easy on yourself by simply remembering to do this step, also you will be putting less strain on the mold!
It wont hurt to do this step a few times throughout the drying process.
Mortaring the two sides together:
When it comes time to put your two sphere sides together you will be faced with this question.” What type of mortar is best??” I recommend thin set. Thin set is typically used for tiling and you can find it at your local hardware store. The reason most people use thin set over mortar is because it is just as it sounds, thinner. However, in this case thin does not mean you compromise strength. While achieving a tight seam between the two sides thin stet is also a little stronger than regular mortar.
Hiding the seem:
To successfully hide the seam between the two sphere sides I recommend blending the seam with left over thin set or grout. Wait about 1 hour for the thin set that you bonded to the two sides together to dry before blending. You can use a sponge and add some water to smooth over the seam and blend into the rest of the sphere.
I have included a video below for how to use these molds.