I just took this. It was split/stacked in spring of 2015....so 7 years ago. You can see a distinct line where the the previous stack that I burned this past winter was shading it. In my case the graying is from the sun. Everything (except the wood) is wet seeing it's been raining here the past couple days. You can also see why I started stacking on two pallets. It's not too bad here, but in places the pallets have pretty much sunk into the ground making them useless.
I've experimented some over the years with how I burn it. First coupla years I would burn the uncovered wood stacked outside until a snowfall came or until I couldn't get to the outside stacks due to snow or mud. Then I would switch to burning just the ash out of the crib. Usually that was Jan-Feb-Mar timeframe. I was first thinking along those lines too that I was trying to burn too cool by choking the air down too far. The next couple years I would take a few weeks worth of the crib wood wood and burn that at a hotter temp. Still ended up with same result. Now I have been just blending it all together. Take a wheel barrow load of outside wood, 2 of what I would call seasoned wood that spent 2 years outside and 1 year inside crib, and 1 wheel barrow of the unseasoned but dry ash. Seems to going better, but I still get some buildup, but not terrible.