When I started, I was getting a lot of alternators which I'd separate into Cast Aluminum, Irony Aluminum and #1 Copper. Getting the copper wire from the alternator armature meant getting out the cardboard that held the wire in. For quite a while, I used needle-nose pliers to grab all those pieces of cardboard and pull. Very labor-intensive and didn't always work, so I'd use a small punch (like a leather-work punch) to work it out. Even more labor-intensive to the point that it wasn't cost effective. I'd also tried using a chisel to widen the spaces so the cardboard would fall out..
I'd been told about throwing the armatures in a fire to burn the cardboard so I tried it in a bonfire. I'd done this in winter, so after they got real hot, I fished them out of the fire and threw them into the snow to cool. All I got for my efforts was charcoal that was even harder to deal with than the cardboard.
Then one night I got a BFO (Brilliant Flash of the Obvious). I'd been loading the woodstove, so I got a real good bed of coal, threw in five armatures, completely covered them with the coals, threw in a couple pieces of oak on top of that and left them for about 15 minutes. When I came back and fished them out with the poker; the armatures were cherry-red, the wire was even redder and the cardboard was completely burned away. Threw the armatures in a bucket water (listen to the LOUD hiss and watch the steam) to cool down. Now the wire practically falls out.