I use charcoal too for my orchids. I combine it with coconut husks and broken clay.
Charcoal is common here as a medium for orchids. It is actually burned wood chunks and they are cheap and orchids grow well with them.
Coming from where I am, we have plenty of coconut trees here. I usually collect fallen coconuts around my neighbourhood park after rain. It is moist and makes it easy for me to pull the husks out.
As for clay, I usually keep all my broken clay pots and break is someone into small pieces as a medium. I love this part of breaking the clay pots as a form of de-stress
. Seriously, I sometimes drive up across the causeway to Malaysia to buy cheap claypots there due to our exchange rate. I use the claypots as my medium mix for my orchids.
That's how I have been using all these years for my potted orchids.