What makes a pine airlayering successful?

here is a link to an Instagram post from bonsai.kazuo.musume - https://www.instagram.com/p/B8Sv58sDhyR/. In it the bonsai professional seems to attemp a pine air layer.

I’ve been told a successful application of this technique is next to impossible for most conifers. In the video and on the surface it looks like he’s placed moss around the ringed part of the trunk but having tried to air layer conifers and failing I know it’s not that that simple.

My question is what are the key considerations for performing a successful pine air layer?

From my personal experience, training and research I believe the following comments are a fair summary.

Normal air layering practices may not be reliable and often damage the parent tree.

In other words it is possible but not consistent! I have successfully air layered JWP and JBP with traditional techniques but it is much slower. Often takes two years and can fail just as often as it succeeds. The key seems to be the age and health of the material. The younger the material and the healthier the higher success rate. Key factors are any of the variables that also affect successful rooting. A great summary of key factors can be reviewed in the section on successful rooting of cuttings. Dirr " Reference Manual of Woody Plant Propagation". After all when air layering we expose cambium and wait for it to successfully produce roots from that location.

The most successful approach to air layering pines that I am aware of is when it used to propagate young stock for Bonsai.

Key points
Air layering one year old wood which is very vigorous and healthy!
Timing - preparation begins in April
Retain only one candle!
Top must be trimmed horizontally.
Air layer must be specific distance below lowest needle bud.

In this case air layering is used to propagate specific cultivars on their own roots. Most successful on JBP due to their vigour.

If you are interested in more specifics they are contained in the following articles!
Bonsai Sekai No 169 May 1984 " Air Layering a Japanese Black Pine"
This article was followed up with practical research, duplication of the methods and reported in English by Carl Morimoto in Golden Statements March/April 2004.

I do not recommend air layering pines as a regular practice for design purposes. I do use it create special cultivars on their own roots for Bonsai cultivation.