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When I get an idea in my head I am so determined to make it work that I sometimes wonder if it will ‘kill’ me first! This was one of those ideas… I was on a mission to create another orb design; but not just a typical one, I have to be super unique! With the help of a volcano and ingenious thinking see how I managed to make these DIY Rock and Concrete Orbs work.

The Spherical Mold:

I wanted to create a casting from the inside of a mold, a sphere of course. Well, if you have ever tried to find a perfect sphere it’s not easy! I bought ball after ball and cut them open. Nope, not smooth enough. Basket balls have wierd seam lines inside. Other balls shrink to a limp skin. Plastic orbs are next to impossible to find… Soooo, I had to do what I usually do; make one.

My ‘Go-To’ method of making a mold always seems to save me.

What you need to make DIY Rock and Concrete Orbs

  • One box of corn starch
  • One tube of 100% Silicone Caulking
  • Old bowl
  • Gloves and good ventilation (super smelly stuff!)
  • Caulking gun, knife to cut it open
  • A smooth well inflated ball (cheap kids play-ball)

Have your ‘master’ ball ready by sitting on a bowl for stability.

Squeeze the entire tube into the bottom of the bowl that is well filled with the corn starch. The intention is to keep it suspended in the starch so that it does not start to stick on the sides. Keep it in one mass, tossing and working in more starch  so to get less and less sticky.

Try to keep a layer of starch between it and your fingers as well.

Turn and toss carefully incorporating more starch  and it will become less sticky.

After it absorbs more and more starch it will start to become moldable as it won’t stick to the fingers as much. This is so much like making a dough (I guess my years working at a bakery helped!).

Roll in your hands to make a ball of even consistency.

Flatten the ‘dough’ on a flat surface that has a dusting of corn starch to about 1/4″ thick.

The mix starts to set pretty quickly so immediately place it over your form ball and smooth it out. Do not worry about the edges or excess. I was aiming to have a good 1/2 of the ball or bit more covered.

It will usually set with in 30 minutes I find. When you you poke it and it feels like rubber then it is set. It popped off easily and I finally had my sphere mold. It is flexible but also keeps it’s shape well – perfect!

The Rock:

As you know by now, I love rock! It has to have some character, I’ve always marvelled at the way that lava rock is made, cooled lava from a real volcano. It is available as the internal rock for BBQ’s and also as a landscape type mulch. I used both types, but the bagged lava rock was larger and more colourful.

Which Concrete Mix to use:

I am always trying to get so much done (life of a blogger & maker) so I am happiest if I can use one of my quickset concrete mixes. I used the Quikrete Fastset Allcrete on this project but the Rapidset Cementall will also work here (it ends up lighter colour)

Both these mixes can work at various consistencies. I did try a few variations and the results were all great.

If you would rather not see the any of the stones in the final form you can mix a very fluid mix and let it run between the rocks that line the mold. If you want to see more of the rocks you can use it more as a thicker mortar and just have it between the rocks.

You should experiment… I did realize that it is strong and holds the rocks together even if there are some empty voids.

The Method:

This is not a perfection type of orb, it has a lot of character and will be quite unique. There is somewhat of an element of magic here as to how it turns out; but that is what makes it so refreshingly different.

The ingenious thing about a sphere is that you can work in partial portions. Gravity is something that will work against you so working in smaller sections is better.

Once one section is set (about 1 hour if it’s warm) you can move it up the side to then work another bottom section next to it.

Place that set section on one side and then add more in the bottom. Slightly mist the existing set concrete to have better adhesion.

Add rocks by letting the mix run in between or ‘mortar’ the individual rocks where you’d like them. You are in charge here.

You can continually adjust position to ‘fill’ as much of the form as you like after each addition is set. My vision in my mind was to resemble some type of ‘carved-out-of-rock’ orb. The hollow void will be great for the other ideas I have!

I love the flexibility of this mold! It does tend to stick but can be worked lose with a bit of manipulation. I do not really like the gunk that builds up when using a spray release like ‘Pam’.

The Reveal:

Once you pull it out of the mold you will be amazed… Isn’t that so interesting?! So many elements of design, form, texture, shape and colour! Yes, colour! You can add some concrete colour to the mix to have some variations of colour.

Ta-Da! So unique and a perfect accent to the natural landscape of a garden.

Each one will turn out with it’s own unique pattern.

The motto here; don’t give up, there will be some way of achieving what you want if you persevere!

Place these DIY Rock and Concrete Orbs in the garden or anywhere that needs a bit of natural interest. ‘But just wait to see what these will become… another vision has popped into my head!

Happy concreting!

barbmaker

I'm an artist & I make things... all kinds of things.

This Post Has 13 Comments
  1. I have been trying to figure out how to achieve this effect and you nailed it! Thank you Thank you Thank you;-) Now off to try this piece of art.

  2. I have collected glass globes for a one time use.. just make sure you can get your hand inside to put in the cement/ rock. I love all the things that you do , especially the geode lamp.. haven’t gotten to do any of your ideas yet. We are building a new shop on the property so I can do projects…. Can’t wait to get some made …. I”ll share pictures We have been doing pendants… Mostly using combination of resin/ jewelry/ driftwood .I”ll send pictures another time.

  3. Love your concrete ideas. Living on a social security check but would love to try some concrete art while I can. I missed saving the one for trellises.

  4. I saw the comment by Rose Marie about the trellis and thought of the orb you made with fleece. You could use that like a trellis and grow ivy on it ! I have made an orb but not the fleece one yet. Love your work. I have several smiling rocks.

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