Question about Brush Stiffness

There was a question about brush stiffness in one of The Shave Den forum postings about floppy and brush stiffness in general.

The questions were:

1.) Is there a difference between Floppiness and Lack of Stiffness?

2.) Does grade affect stiffness (pure, best, silver/super)?

3.) Which manufacturers or models are stiffer and which are less so?

I posted the following answer:

"All good questions. There are many variables in brush stiffness. Type of hair, loft of brush, density of brush and so on. Some rules of thumb would be Silvertip is softer (less stiff) then regular badger, shorter loft is stiffer than longer loft and finally denser brushes (read how many hairs packed per square cm). Floppy just means when you wet the brush the hairs spread out all over the place indicating a lack of stiffness or backbone to a brush. As far as manufacturers go, that's a research project all it's own. I know, I'm generalizing here but even between the same brush what's floppy to you may not be floppy to someone else or maybe the manufacturer happened to pack the brush a little denser. "

As a an added note, I consider floppy to have very little backbone so when the brush spreads out it has very little spring back. An ideal brush for me would be one that was packed very densely, a loft around 50-55mm, a knot of about 23-24mm and a high end grade "best badger" that has fairly stiff bristles with soft tips.