I have always assumed that BP comes from:
BP - blended fur and polypropylene- a blend of stippled hare fur and seal (for the body)
with a polypropylene rib I assume
What do you use for the rib?
In an earlier thread zonnkers used the following mix for the body:
50/% Hare back fur and 50% Natural seals fur with maybe a pinch of bright Red Seals fur, this is used on most of my "Hares ear" nymphs and dries , I find the proper Hares ear fur to short and end up with most of it on the bench and not in the dubbing.