Geez,
SWIP was so busy prattling on about what he thought might make the tetra trap more effective (boiling in H2O, filtering), that he at first didn't stop to consider what you had offered here. After satisfying himself that the boil/filter combo wasn't going to take care of the problem he came back to read again, and this time read better. He followed the steps you laid out with painstaking attention to detail, and the result was just as you suggested. Very clean pfed-hcl.
The only trouble now was that he really wanted to do a FB reaction since he has yet to be able to avail himself of rp alternatives. On that note he foolishly decided to turn his hcl back into FB, and the yeild was even worse than he expected. This started him thinking about several packages of highly gakked generic red hots he just happened to be hoarding in reserve. Ignoring your caution that the procedure you have was for 120's, he started back at it, and before long he had some nice FB crystals. (Of course this time he deviated from the procedure and performed the tetra trap with VM&P instead of xylene.)
Testing the FB with the burn test he was at first pleased. The sample melted quickly and uniformly into clear liquid, and upon further application of heat from the match, it all vaporized and left nothing at all on the foil. SWIP noticed, though, that the sample seemed to give off a burst of vapor very quickly, but then it took a little more heat to get the rest. Hard to say for sure when melting powder on foil with a match. But also, the first vapor was clearly FB but the smell of the last was different. He tried it again, watching more closely, and sure enough, right after the powder melted a puff of pfed smoke was produced, but the clear liquid remaining required additional heat before it vaporized, and did not smell as it should.
Thinking this over a bit later, SWIP thought that the delayed melting point of the unknown gak might be an advantage. He set up a coffee pot with an inverted cup that he used to sublime I2, and placed about a gram of FB. He then filled the inverted cup with ice and applied heat to the pot. As he watched the FB melted, vaporized, then crystalized on the sides of the pot and into the cup. Eventually there was a quantity of liquid that would not vaporize at this temperature, which was about the same as used for the tetra trap. SWIP didn't measure but he thinks it's right about ~100 C. He was careful because he didn't want to burn anything, or to contaminate the end product by getting the gak hot enough to vaporize. In the end he was left with some very fluffy crystals that actually resembled those you get from sublimation of I2, in form, that is. Remaining in the pot the liquid had now taken on a familiar brown color. SWIM isn't sure what it is, so for lack of an alternative he will refer to it using the scientific term, "brown shit."
Following this procedure it was clearly evident that the FB was completely clean. A small sample went up in smoke almost immediately when heat was applied, and left no trace behind. Overall SWIP has been quite pleased with this method, one drawback being the fact that the method is rather messy. (If anyone has a better method for sublimation, SWIM would love to hear about it!) The other difficulty is with yeilds, which aren't actually bad from the vaporization, but SWIP doesn't approach fifty percent yeild once he has treated with JD, xylene, VM&P and on top of that run through the tetra trap. He is careful about overheating in each step, careful about using too much H2O in the TT, but evidently has yet to develop the proper technique. (He would love to bee a fly on Shorty's shoulder during one of his extracts.)
One other detail that SWIP doesn't want to leave out is the newly revised gak list of the red hots he used. He actually tore off the list of inactives to be able to list them here, but somehow lost them before he made it to the computer. It was the worst list he's seen from the evil Gak-Mongers yet. Several items he has not previously seen listed, and which he had never heard of previously. At step beyond cross povidone, PEG, O, OII--whatever that is.
At any rate, SWIP has yet to try it, but suspects he can get similar results just by running the TT then vaporization cleaning. One other possibility is that, with careful heating, it should be possible to melt only the FB, or if not to pan it off to the side of the container, since the FB tends to seperate from the brown shit once it's melted. SWIP was going to try it with a couple of raw pills ground up with some sodium carbonate and MeOH. While he doesn't really expect that to work, you never know!
PP