I had mixed success with a bunch of air layers I put in place last year. Half of them got shredded by godamn squirrels for starters! They were all spag moss in cling wrap. I did a bunch of Magnolia AL on my girlfriend's grandmother's HUGE tree which her husband gave her the first year they moved into the house about 60 years ago - he passed away a couple of years back and she isn't in good health. Thought it might be nice to try and get a few new plants from the tree for the family should she move into care soon. I separated 3 so waiting for spring to see if they leaf out, there's a couple more on the tree still as they hadn't developed roots at all but have new buds on the branches.
I also tried 3 on a silver birch but wind broke a couple off, the remaining one hasn't done anything since September. It's got some good swelling going on so I'm hoping as we get into spring it will pick up and start throwing out some roots. They weren't really for bonsai just more playing around.
I like the idea of using a pot around the branch - is wrapping some cling wrap around that then OK to keep some of the moisture in when I'm not able to check every couple of days? I also like the idea of using bonsai mix rather than spag moss. I bought a 50L bag of this stuff to move some of my collected material into training pots, but I reckon it would work quite well for some AL?
http://www.kaizenbonsai.com/premium-bonsai-compost-no2-new-improved-formula
Also when picking a spot to AL from, is it best to pick somewhere with a half decent amount of thinner branches with leaf growth already in place that aren't too far away from the layer? If I'm trying to air layer something with decent thickness it's likely it could be quite a long section before there are any leafy areas. If not I'm guessing AL on a thick ol' branch and then removing it, but also removing a lot of the top growth is going to really f**k with the trees balance when it's removed, and then struggle to throw out new growth from lower down.
Probably not explaining myself very well...
What I did with the Magnolia was to chop some older branches off in early spring which then threw out loads of new growth over the next couple of months. I then put air layers onto the new growth towards the end of summer when it had got to about 1/2 inch thickness. As I say these weren't for bonsai, so in theory I could do the same and then air layer behind the cut and have a loads of fresh growth on the top. Good luck interpreting what I'm badly trying to explain!
Also that's a sweet looking result Colin!