Just a few months ago, I ran accross a 'universal' solvent welding product that listed 100% THF as the only ingredient on the MSDN. When they gave no info on the product other than highly toxic and flamable I knew it had to be worth looking into. They leave out the resins normally added to the material-specific welding solvents, to achieve the best possible bonding between different polymers.
I think I read somewhere that THF had just reciently been upgraded to a higher restriction profile. So if you do find it to still be available, stock up.
Either way, do be careful. THF is nasty, to breath, touch, taste, hell just remembering an hour sealed into a bathroom distilling that shit nearly triggers a gage reflex. And according to credible sources it is even more susceptable than ether in the formation of peroxides which can spontainiously explode. Sunlight, open flame and O2 exposure should be held to an absolute minimum, and don't even think about storing, transferring or using THF in any plastic container other than PTFE. If you were to drop a buick in a vat of THF, I doubt you would have much left except foam a week later.
And on the eight day, God created Meth...
... and hasn't done much of anything usefull since!
