insulated needles are perfect for doing blend. There is no problem with using them
Page 232, in Chapter 16 "The Blend Method" in the book "Milady's Hair Removal Techniques", it says in the "DO's & DON'TS" box,
"Do not use noninsulated tapered needles."
I guess I was thinking of galvanic electrolysis, and how the blend uses some galvanic current:
On page 224 of the same book, in the same type of text box, it says "Don'ts of Galvanic Electrolysis" "Do not use tapered or insulated needles."
It also says on page 164, "For this reason, insulated probes are not preferred for the galvanic modality or the blend method." This has to do with making sure the sebaceous gland is also killed (I think they may be referring to the bulge, although I've also heard that it is thought that stem cells are distributed throughout the entire follicle, not just in the bulge), because "the lye pattern differs with insulated probes".
It also says, "There may also be some question as to the durability of the insulation on the probe and whether the lye produced by the galvanic current would break it down."
I know you recommended this book in a previous post on Hairtell. I myself am not sure what to think about insulated probes being used in blend. I'm not an electrologist.