Interesting Experimentation! As far as making a straight cut on the scion and rootstock, the block plane sounds good, but I'm finding the technique difficult to envision. At the HOS grafting classes
this spring I did notice a problem with knives. It was suggested every participant bring their own, and there were a number of loaners - very
sharp "paring knives." Most participants were having difficulty achieving straight cuts. I tried several knives and quickly discovered the problem. Their thin steel blades allowed them to flex, causing a concaved cut. Never clean or smooth, the torn edges on both scion & stock weren't looking good...
What did work were our "real" grafting knives
- ridged stainless steel blades, sharpened from only one side (though mine came tapered from both?). I've heard that a "good grafter" can make the cut in one slice - I'm getting better... But I've found that careful "whittling" can bring them to precision! But no tongue?
It's a mechanical measure that maintains the critical alignment of at least one side of the cambial layers. With a scion and rootstock of identical diameter, "just taping" might work fine, but size discrepancy is generally our greatest problem.
And Electrical Tape... the debate continues
~ I use it for top-working all the time; but for bench-grafting delicate scions... it's primitive
. Modern budding-bands are best: they give controlled tension at the joint; shed rain; exclude air & moisture; allow for expansion; and eventually decay from sunlight. What more could you ask? (just get the "Big ones
!") Other than dabbing on a drop of grafting seal to the top of the scion (to keep it from drying out), you're set!
My concerns without bands, or tongues: a shifting of scion alignment; bending, twisting, or pulling away - and if you've bound it extremely tight; a restriction of the natural expansion. And with grafting "wax" over the electrician tape you've formed a very hard "cast."
I've never noticed an "unsightly" union caused by the "tongue" of a whip? Eventual burls are due to a slight incompatibility, or a vigorous scion with too restrictive a rootstock. But one thing about avoiding a "tongue" - that's where the bloody