Sorry to necro this very old thread but.....
First smoking kava is gross. It works but we dont know the long term effects.
Second....Isopropyl washes are safe as long as you purge the final product with heat and its recommended to use 99% iso. When you make an extract with iso or with high proof ethyl, all the active ingredient is evaporated off (alcohol) and all that is left is distilled water and your exctract. But you must make sure to let the exctract dry. Alcohol evaperates when mixed with air. The purer the solution, the faster it happens. For more info on iso evap rate check this out.
http://people.uncw.edu/lugo/MCP/DIFF_EQ/deproj/alevap/alevap.htm
DO NOT FORGET THAT ISO IS A POISON THAT CAN CAUSE BLIDNESS, KIDNEY ISSUES AND DEATH. IF YOU DO USE ISO MAKE SURE YOU KNOW WHAT YOUR DOING.
Again sorry for the necro