What is this around the hair please? Gingers often, greys sometimes, never black

Hello lovelies , Thanks in advance for reading.
My little salon has been going well thanks for your help.
My question I have relates to transgendered clients that I have with ginger and grey hairs. It doesnt happen with black.
The hairs can be real stubborn, I get good lye and thermo treatment to the follicle but they give a heck of a struggle when i tweeze them.
Attached is a pic, sorry its not real clear but it shows the sheath stuff around the ginger hair that was treated. Is this normal or common?
Many thanks Maddy


Always the bottom line is that the client shouldn’t feel the hair being taken out. If they are then you are not applying enough current or your insertion is no accurate.