I really liked this tree when I first saw it.  I'm not sure where I have any when-I-got-it shots, but I'll have to look for them.  The canopy was full and the trunk was thick with some interesting bends towards the top.  There were some obvious chop marks and lots of green wound sealant.  I figured I could work around those and get them healed up.

After getting it home and getting the wound sealant off of it, I determined there was a fair amount of rot hidden underneath.  After removing rotten wood, I applied minwax wood hardener then filled it with wood filler to get back to a reasonable depth.  There is considerable wood filler in this tree.  I then reinjured the scars in an effort to get it to scar over, and added a better wound sealant.  You'll notice a plethora of brownish-gray spots all throughout this tree.

I'd intended to airlayer this spring but I got some odd stuff happening in the foliage so figured I'd let it recover.  The new leaves were turning black and falling off.  The tops of the branches were too.  If I recall correctly, this one may've scorched in my greenhouse, then got moved outside right before a wet period.  After removing the affected growth, I sprayed it with safer's soap or something similar and it cleared up.

I'd be lying if I said it was thriving, but it is still alive.  I'm not sure what is going on, but it looks like the rot, coupled w/ whatever the black stuff was last spring, has killed off large sections of the trunk.

It looks a lot like it did in the pictures above.  I'm getting a lot of new growth on it lately. 

If I think about it, I'll try to get a picture and update the thread.

 :)Wayne  nice looking maple. What variety?
Art

Your first two photos of the tree did not inspire me. The knobs and the abrupt angle changes at the trunk chops, just not a coherent image to my mind. I just said to myself this is not going to ever turn into much.

BUT, ta da, with the rotten wood removed, that trunk has a whole new character. There is interest there now. Hopefully you can get it to recover, pick up vigor, and start really growing again. If you can put it into a large grow pot, or the ground, and let some escape branches extend out for a couple seasons I think the transformation will be dramatic.

But I would guess you may have been doing bonsai longer than I, so I will ask a question. I was thinking about what caused the rot, and the loss of the branches. The rot could be from water under the old green cut paste, but the loss of branches does sound like heat stress. You mentioned over heating in a greenhouse as the cause of the scorching. I looked at your location. South Carolina, zone 8, why would you ever put the tree in a greenhouse? I winter my maples outdoors here in Zone 5b. I have to mulch them, but they are happier with a sharp cold rest than they are being 'babied' in my old well house which tends to stay above freezing. Too warm in winter (my well house) they come out of dormancy before they can be put out on the benches. Got to keep them good and cold. Not knowing your specific location, I would consider just moving the tree out of the sun and out of the wind for the winter, no real need for temperature protection for winter in zone 8. Top of the bench to under the bench.   

And in summer, as you suggested, this may very well be a maple that has to stay in the shade. They are understory trees after all. 

But I don't know your situation. I could be completely off base. But it did strike me as odd, to put this tree in a greenhouse.

Definitely post photos in the future.