AusBonsai

It's been about 8 weeks and both top and bottom are looking ok, but there is not sign of rooting in the airlayer.
The vertical scar is from when I cut away the bark and cambium. At the time of the airlayer I'm certain it was back to bare wood.
I did a few others on other plants - olive, ficus and tilia. So far only the ficus is showing (many) roots.

Have I not waited long enough?
Can anyone read into the picture at all?

Thanks.

It has bridged the layer - that is the bit joining both on a a bit of a spiral. The tree will always try to bridge rather than have to put pout roots. Recut it and did you use a rooting hormone ?

Thanks Tony,
I'll do that tomorrow.
Yes, I used a hardwood root liquid. Yates Clonex, Red.

Should I expose fresh cambium on the upper portion?

Difficult to tell, but you have to scrape back all the cambium to stop the bridging. Recut scrape right back more hormones and try again. You could also put a tight ring of wire ( a tourniquet) to also stop bridging.
Cheers
Kirky

100% bridged as suggested by Bougy... re-scrape the area, you can re-cut the top if you wish but just cleaning it up and re-applying the root hormone to the top edge should be enough...
EDIT: Kirky beat me to it... but just to emphasise!