Some Final Experiment Results from the Sphere Mold

Waterproof plumbing tape sticks where other tape peeled off.

I had a few final thoughts and a final experiment on my sphere mold.  My goal was to create a low cost sphere that could be used as a base for making mosaic gazing balls.  The sphere had to be able to stand up to the weight of glass and grout, and be able to withstand outdoor weather conditions.  I had hoped to create a mold that could be used to cast numerous balls.  As I blogged last time, trying to create a sphere with expanding foam was futile.  However, I don't consider it a waste of time.  As Thomas Edison is quoted as saying about the light bulb, "I have not failed.  I have found 10,000 ways that won't work."  I will continue to experiment until I find what does work.  I merely have to rethink the situation. 

In the last blog post showing the still wet, sticky foam that remained inside the sphere mold.  I had left it to dry wondering whether the foam could be removed from the mold.  I had coated the mold liberally with mold release.  Once dry, the foam did not release from the mold.  I guess that was wishful thinking on my part.  After all, the product is designed to stick in cracks and not come out.  However, that started me thinking in a new direction.  Suppose that each mold was a one off mold rather than a reusable mold.  What if I sprayed foam to fill each half of the sphere mold.  When the foam was dry,  maybe use a saw to saw the foam level with the top of the mold.  Then glue the hemispheres together with construction adhesive.  That might possibly work.  I guess I will have to experiment. 

My next question is whether the mold itself would be waterproof enough.  It is raining this morning.  I am going to toss the mold pieces outside to see how they hold up outside over time.  I have seen papier mache' pieces designed to be kept outside.  The glue made them waterproof.  So I have some hope of the mold lasting in outdoor conditions.  Whether my method works or not remains to be seen.

Another experiment was to find out if a different tape made a difference. As I blogged last time, the mold was highly resistant to both masking tape and duct tape.  Both tapes tended to curl off from the mold.  Long time readers know that I generally wrap my sphere base in a reflective, waterproof plumbing tape before gluing on the glass and grouting the ball.  It may not matter if the mold is completely waterproof if it is covered in two additional layers of materials.  The waterproof tape has a very thick, sticky adhesive.  It is much stickier than either of the other tapes. I tried the waterproof tape.  It worked.   The waterproof tape is not peeling up off the ball.  So maybe, if I made taped foam filled hemispheres together I would not even have to purchase some construction adhesive.  Hmmmm......It sounds like another experiment is in the cards.

(Note:  the reflective, waterproof tape is not the reflective tape that is used to tape dryer ducts and air conditioning vents.  Its shiny exterior looks the same, but the adhesive is different.  Make sure the tape is marked waterproof.)

Now that I know the waterproof tape will stick to the ball, I also had another thought.  Suppose I had made the mold as I have blogged about.  Then I cut a hole large enough to remove the ball.  Then I filled the ball with sand or gravel.  Then glued the piece of the mold I had removed to extract the ball back in place.  That ball would be as solid as could be.  The waterproof tape, silicone used to glue on the glass, the stained glass, the grout, and the sealer for the grout would pretty much make that ball impermeable. It sounds like another experiment is in the cards.

I am sure the everyone wonders why I persist with trying to make spheres out of ridiculous materials.  The main reason is that I like to make gazing balls, but they are expensive to make.  I like to keep my hobby costs down.  For the mold I was making for these blog posts, the costs came to roughly $1.74 cents worth of glue. $3.38 for the spray foam, and some scrap flannel.  Playground sand - $3.99 for a fifty pound bag.  Or aquarium gravel is $2.09 for a five pound bag.  Child's ball to use as a mold - $1.99.  So about $11.10 for this project.  (Cost figured using the figure for playground sand.)  I have not checked to figure out volume, so it could take two bags of aquarium gravel.  I count the flannel at no cost the costs for the material had already been absorbed in other projects.  It would have been thrown out if I had not used it for this project.  I expect that many people  have some old flannel shirts or an old flannel blanket that have seen better days and could be used in a project.  Roughly eleven dollars is a lot less expensive than some of my options.  Sometimes I can find a bowling ball for free, but many sell for as much as $35.00. 

The costs for Hypertufa in round numbers:  concrete mixing tub, $12.00, portland cement $11.00, pete moss $10.50, vermiculite $12.00.  That comes to $45.50.  This is presuming that you already have a hoe and a trowel.  A half-sphere mold can run $20.00 to $35.00.  If you have a lot of patience, you can get by with a single mold and cast the half spheres sequentially to get two hemispheres to glue together to make a ball.  Otherwise the costs for the mold doubles.  The other problem with casting Hypertufa is that the materials are generally sold in large batches.  For example the portland cement comes in ninty-four pound bags.  Sometimes you can find them in fifty pound bags if you are lucky.  That is a lot of cement compared to what is needed to make a ball.  And once you open the bag, the clock starts ticking on the shelf-life of the product.  A Styrofoam ball at the craft store can run about $17.00.  Larger ones can cost much more.  So perhaps you can understand my quest for a less expensive option. 

Sooner or later I will get around to experimenting on spheres again.  I am planning to put my current project outside to check to see just how waterproof the mold really is.  Other than that, I will begin working on the toy-sized lamb project.  It may take a few days to get started, but I should have some photos soon.  I also have a couple of other projects to blog about.  Check back on Thursday for the latest.