Knowing these two key points air layer Japanese black pine bonsai is not difficult 

Thank you for creating this video with suggestions. Your suggestion to not close plastic too tight so that air can get in is very helpful.

I also propergate airlayered jbp,rpine & with my older trees ive airlayered i do them in the hottest times of the yr usually aftr 2nd flush ,i mix a paste with both liquid & powder & mainly use a pot with another round disc 2 support the roots from growing straight down.If the layer is going 2 take longer then 4-5wks i add an outer layer of sifted potting mix/ larva rock so that it doesnt stay 2 wet through the cold rainy season!!

How long to take root