Other bees, myself included, suggest you read Fester's "Deconstructionist Thought" thread and extract with a method that actually breaks the polymers down.
The STE isn't enough anymore. When VE posted that method it worked beautifully on my favorite white 60's. If I relied on it now with the same pills, I would have low yields, meth full intermediates, and the a/b would not be very efficient. The inactives list is the same.
Unless you incorporate an attack on the polymers in the extraction method, you are going to have less than clean pseudo and you will foul the reaction with reaction inhibitors and struggle with a/b inhibitors. Until you break those polymers, you can't separate them from the pseudo. After you break them down, you may not get all the fragments out of the pseudo.
Such is life these days. I've seen pseudo that is pretty damned clean for pseudo these days that still won't recrystallize to brad-like spikes in alcohol. You have to have clean pseudo to see those, and when you have those you know your reaction will be a great success.
I have the impression -- and it is just that, no more than a hunch-- that the Eudragit polymer that is the reaction inhibitor is the one that leaves the whitish stain. It can be broken, but the fragments that are not removed impede the a/b extraction. These will give you a brown stain on foil when you vaporize the pseudo. This is what you see when you break the polymer that leaves the whitish stain. This fragment seems to foul the a/b process. React the pseudo that leaves a whitish stain and yield is limited, break the polymer to improve yields, but you will need to do more than a simple a/b to get your yield. Sort of a choice between the devil and deep blue sea, or polymer, as the case may be. The whitish stain will give you a low yield with a clean interface, the brown one will give more yield but with trash at the interface and difficulty basing and extracting. Just some observations, no conclusions yet.
