I wanted to pass on a little knowledge here.
First, I baked a batch of Fina today, 45 minutes at 250 degrees, and I did not vent (which some say could increase oxidization and thus degradation). The key is to suck all the air out, or all that you can, with your syringe.
Secondly, someone hypothesized that the Tren gook in the vial one frequently gets is from not enough BA/BB. That very well could be. I recently made two batches of Fina. Both were baked, both were placed in the fridge immediately afterwards, but one had significantly more BB (since I don’t like increasing BA), than the other. The one that had more BB did not get Tren gook.