Hey ronrr,
Some hormones such as Test E, Deca (Nandrolone Decanoate), Boldenone, etc., do not need BB, because these hormones do not crystallize.
As far as Tren E, I have not seen it crystallized at 100mg/ml.
Even when working with hormones that do not crystallize, some people choose to use BB to make the solution thinner, so it flows through a small needle (25 gauge) easier. I don't use BB at all, even when working with hormones that tend to crystallize (Test Prop, Mast Prop). I just warm my oil before I inject to dissolve the crystal and thin out the oil.
As far as what BA and BB percentages that are commonly used:
BA: Pharmaceutical companies use 1%. Home brewers use 2%.
BB: Pharmaceutical companies use 20%
(
TESTOSTERONE CYPIONATE INJECTION, SOLUTION [WATSON LABORATORIES, INC.])
I hope that answers your questions. Let me know if you need help with any thing else.
Cheers mate.