I just got into some wood that was leftover from in the shed from last year, red oak. Mind you this wood is 4 year css and in the shed totally protected since August of 2017. Decent sized splits, not monsters by any means but not kindling sticks either. I just put 5 pieces in my stove and they still sizzled and bubbled a little on the bottom. Unreal.
There's still water in your firewood no matter what. If your wood is at 20%, 1/6 of the weight that you put in your stove is water. At 10% its 1/11. I also see a bit of steaming out the edges on 4 summers dry red oak when I relight my stove. For whatever reason, oak seems to be able to hiss when other species don't. No matter what species you are burning, the water is there and you are steaming it off.
BeechNut I'm sure you know already, but if you can place any amount of that wood inside for a few days (week) before you use it, you'd see a difference in the amount of sizzling/bubbling.
I've been using quite a bit of Ash this year that I'm pretty sure I got back in '16 (css) and I find some that sizzles and other splits that don't burn really well, but no sizzle. Very interesting.
I still see the sizzle on wood that has stacked, top covered for years sometimes. It is what it is I guess.
