Backyard Aquaponics
A place to discuss aquaponics

why does it matter if there are flat spots? My substrate doesnt have to be a perfect sphere.. or even spherical.

brian

Flat spotting wouldnt matter too much, but are you going to roll all those balls by hand?
I dont know how the professionals do it, but i would mix my combustible material with my clay, have it runny enough to be easily extruded and chopped at the right size (homemade rig would be used for this, like a spaghetti maker, but single strand), but also thick enough that it isnt liquid, in this state it may settle too much if not rolled for the first part of the drying process.

Any further progress on this idea? I'm thinking you could start with a dry blend of clay dust and wood sawdust. Slowly sprinkle with water as it rotates in a cement mixer. However, it would need to be a smooth one, no paddles. Like what they use to make candy. With just the right amount of water, it should start to ball up. If you continue to run the drum, it should start to dry out on the surface. Add a little fine sawdust to coat them and then they should not stick together at all. Let them dry in the sun and pop them in a kiln.

You could dust them with something to stop them sticking together during the firing process, even fine sawdust that would burn off during the process might work.

Here is my (completely untested) theoretical method:

1) Start with wet clay. As a bonus, mix in some EM-1 or EM-A (dunno which would be more appropriate for this), so that your end product will effectively be "EM ceramics".

2) Make pellets significantly smaller than what you want as the end result - wet a piece of hydroton about the size you're looking for and put it on a scale opposite the wet clay pellet if you really want to be exact.

3) Use a pressure cooker that will go over 200 psi and has a quick release (if such a thing exists), or something similar to the "cannons" used for making puffed rice.

4) Based on the size ratio of clay to hydroton (again determined with the scale method), fill the pressure cooker partially with your clay pellets, along with an undetermined amount of water (hey, I'm just making this up here).

5) Cook until you're at 200psi and let 'er rip. The superheated water in the clay will convert to steam once the pressure is released, expanding the entire pellet.

6) Now move the batch to your kiln and fire it up. Voila!, expanded clay.



... if anyone tries this, for the love of all that is fishy know what you're doing with your equipment and use sensible safety precautions.

Mmmmm steaming hot clay fountain Have you ever knocked the weights off a pressure

Don't know enough about pottery, From what I've seen in the past a Kiln is a closed environment in which heat is added (gas or other fuel) if we made the Kiln round, like a 200 litre drum, and add a spiral track from top to bottom wouldn't we be able to roll the clay ball made in the cement mixer through the kiln and out the other end.
They would not have flat spots ( no big issue for our use if they did)
There are only small issues with blockages, what if a ball breaks or cracks?
Would they be in the kiln long enough to get them hot enough?
If any bod in Brissy area in interested in trying this ... I'd be keen to have a crack at it, but need more knowledge on the kiln side and the clay ball part.

If you get your system working you could create a specialty product.
Light reflecting expandable clay balls by using white clay and a lot of mica. For those who want to get the most out of an indoor setup.