This is why we use raffia or tape
- wrapped around the branch or trunk prior to wiring,
- make sure that when you bend you ideally have wire on the outside of the bend - adds an extra layer of support to the limb and helps prevent it bursting outwards.
IMG_1186 by Jerry Norbury, on Flickr
A good stiff brush will often remove that stuff too.
It's usually a sign of two things:
- slow evaporation and the wicking effect you see mentioned (highly likely)
- made worse by a poor watering technique - really saturate the entire root surface when watering. Flood with water.
The foliage needs to be pulled in by wiring - typically white pines have compact foliage.
I find the lower trunk to be too vertical - so you could also take the opportunity to change the potting angle (rotate it clockwise) and increase the angle of the first bend to visually lower the apex.
I've been growing larches for almost 45 years - I currently have well over 150 of them.
- I've never had an airlayer work - I've also tried ground layers and they simply killed the tree. Other people assure me it's possible, but not for me.
- every single bud is sacred, they cannot be replaced...
I've also just used a Stanley knife and scraped trunks for years - but I reckon if I could do it faster and quicker, I'd probably do it more.
I buy the high quality tools because, frankly, often nobody else makes such specialised stuff. I'm not shocked at their prices - the stainless steel...
Just ordered the Masakuni airlayer rasp AND the Kaneshin saw AND the Kaneshin 121 air-layer scissors: https://bonsai-tool.com/goods_en_JPY_827.html
Not from Japan though, from Italy, here: https://www.utensilimanzanese.it/?s=mashakuni&post_type=product&dgwt_wcas=1