Vic N

I tried my hand at air layering this past summer, and although it wasn't a total failure, it still may be!! The reason it still may be is that none of my layers grew roots and I've read that the layer can be left over winter and may take the next year. On the other hand only one of my layers has totally failed, the ones that are still going (?) have all developed a callous, but no sign of roots. I may have started these a few weeks too late, but I would like some clarification on a couple of points.

An air layer as I understand, cuts through three layers of the tree:
The bark, the cambium, and the phloem.

This leaves xylem and hard wood (?)
When I did my layers it was easy to see the bark and cambium, but how do you know what the phloem is and if it has been removed? Is it a white material like the xylem/wood, or does it just come off with the other two?
Is there a process that I did not do to cause my layers to not do well?

I have seen posts that reference scraping and even using a torch. Is this something I should be doing?

Thanks in advance! Vic