I've just got some xylene and am excited to try it this time. I've been cooking the bark in a high-pressure cooker, and the water has come out way darker, so I'm hoping this is a good sign! I'll keep doing it until the liquid fades in colour. Thanks for your advice; I'm going to try xylene and heptane.

Is narrow phyllode acuminate better than root bark? I can get either; I wasn't sure what the difference was.

Thanks again for the great advice!