My Sphere Mold

Ball mold cut into hemispheres.

Last blog post I wrote about trying to figure out a way to make a better sphere.  I make mosaic gazing balls.  The balls need a sturdy base to support the weight of the glass and grout.  I have been experimenting to find a way to make a base for the bowling balls that fit the following criteria.  It needs to be relatively inexpensive, easy to make, and sturdy enough to hold up in outdoor conditions.  To that end, I keep experimenting to see what is out there that will facilitate my crafting while staying on a budget.  I am still looking for an easier way to make spheres. 

Interior of the mold.

Before the mold was cut open.

For new readers, a quick recap of what I have done over the last few years in my quest to create mosaic gazing balls.  Detailed directions for crafting the objects are available in earlier blog posts.  I have used bowling balls as a base, cast spheres in Hypertufa, and even figured out how to create a papier mache' sphere that was covered in Portland Cement as a base.  The bowling balls were easy to use as they were already manufactured, but they are not easy to come by.  Mixing Hypertufa was a lot of work.  I was casting in a half-sphere mold because full sphere ball molds are expensive.  Mixing the Hypertufa and joining the hemispheres was messy work.  Plus the Portland Cement was only available in fifty pound bags at the hardware store.  It was a lot more than I needed.  Creating with Hypertufa was only affordable because we already had the concrete mixing trough from doing some home repairs.  The papier mache' base was had to be covered with layers of wire mesh and covered in Portland Cement.    Getting the sphere to retain its shape while covered with wire mesh was difficult, but the project has been able to stay outside summer and winter for the last two years.  All of the projects worked, but all had a degree of difficulty or expense. 

Yes, there are mold making materials available, but silicone mold materials for something the size of a ball would be expensive.  Plus a silicon mold would need to be reinforced so that it would retain its shape when filled.  Casting plaster around a ball would require cutting the mold open with some sort of power tool, creating a lot of plaster dust.  Still, that option is on the table for experimentation at some point in the future.  What I really want is something I can work with in the studio without creating a lot of mess.  Or at least made with only a minimal mess even if I have to work outside.  So this time I set out to try to create a spherical mold that I could use multiple times with inexpensive materials.

I decided to attempt to make a mold using what materials I had around the house.  I did not know for certain that it would work, but I strongly suspected that it would.  In doing some research on papier mache' I learned that people used to make small boats out of paper and glue.  It is hard to imagine what it was like to have the courage to attempt that.  However, small paper and glue boats were a way of life only a few generations ago.  If you could make paper and glue into a rigid, impermeable object, why not cloth?   If it failed, the main thing I was loosing was the time involved.

I used some scrap flannel and glue.  I purchase glue in gallon bottles at the hardware store because that is the least expensive way to buy it provided that you plan on making lots of projects that involve glue.  My mold project only took about two cups of glue total.  The flannel was left over from another project.  In fact, the flannel used in the last project was left over from a previous project.  So getting some of this old material out of my fabric stash was a win in any case.  My real question was how many layers of fabric was it going to take to make the mold rigid enough that it would not collapse when the ball was removed.   When working with my papier mache' ball base I learned the hard way that it would take more layers than I thought to make the structure retain its shape.

Sometimes you just have to guess.  (Note: to see the detailed instructions for creating the mold for see the blog post for Thursday, March 17, 2016.)  I decided to try three layers.  It was an arbitrary decision made solely upon that was how much scrap flannel I had available without cutting more from a larger piece.  It seemed quite rigid, so I decided to give cut the sphere in half and see what happened.  It worked better than I would have thought.  In fact it was so rigid, I had trouble cutting it open with a utility knife.  If I make another one, I will use a cutting blade with the Dremel tool. 

The inside was smooth, although you can see where the pieces of flannel are lying next to each other.  I am not sure how much those lines will appear in a cast object.  For my current ideas of application, I don't think it is going to matter.  In some places it was still slick from the mold release, but that will not be a problem.  I will be adding more mold release when I use it in the future.  In theory, this mold should be waterproof.  I guess I will find out about that as things progress. 

The outside of the mold is not a thing of great beauty, but for this mold, I was not particularly worried about what the outside looked like.  If I make future molds, I may keep that it in mind to make a smoother exterior.  I have a few ideas about how to use my new-found mold.  I will be blogging about them soon.  I have to make a trip to the hardware store before I use the mold.  I think I will be able to show you my first cast ball by the Thursday blog post.  Either that, or I will be blogging about the failure of the experiment.

Check back Thursday for the latest on the ball mold experiment.  Once that has been completed, I will begin working on the small version of the sheep/lamb.