EspritDeLaNature I'm not surprised to see this; benzoin melts on a coal which leads me to assume it doesn't contain much gum, and when I tried washing some opoponax, it was a sticky hellscape.
Interestingly, the opoponax also took on water, swelling up until it looked like a porridge. I tried using a buchner filter to separate the solids from the water, but it clogged it up so firmly that I gave up and wound up using a giant colander and cheesecloth, which still took ages. It then took an eternity to dry, and it still sticks together when ground. The washed opoponax resin is notably darker than the unwashed resin, which is interesting. I haven't burned any yet. I'll have to give that a go soon and report back!