> Bulge
> What is the nature of the object with bulge 10?
> Is it sustainable?

Blending adjusts the scaling of control points on either half of the blend.

In that case with a rather large scale factor (points are spaced at 10 times their normal proportions), your blended surface loops through itself, it is a self-intersecting surface.

I'm not sure what you mean by "sustainable" - but you should normally try to avoid that, surfaces that fold over themselves like this will not work well with some other commands later on like booleans.

It does look rather interesting though!

- Michael