You have a chance to compact and high-fire anything you want, what do you choose/why?

[youngsai]

So, I speak with the vice-president of a chemical company who sells substrate to a lot of hydroponics companies, farmers & different companies of that nature, and they have been sending me samples of different hydroponics substrates to see if I could use them in my soil. We talk often trying to figure out cheap substrates I can use for my soil.

Today they offered me an opportunity to choose a substrate which they will compact under high pressure (and high temperature if I want), inasmuch I first thought of a humus and peat combo, to perhaps play a similar role to Akadama. But thinking about it more, I wondered if there is not a better choice of humate substance that would be more suited to compact to make a soil component.

So I wanted to get everyone's opinion on this- If you could choose a particle to pressurize and compact for use in bonsai soil, what would you choose and why?

Please help me on this, I'm very excited about this and want to make a good informed decision, I was also thinking worm castings or something like that, but that would spike the price until I started making it for myself, so I'm kind of at the end of my own ideas. I invite any open minded conversation on this topic, not just the questions I asked...

 

[armetisius]

Pack and bake

Sand: because under heat and pressure it may form something akin to low grade quartzite but in pebbles the right size without the aching arm to go with using it.