Soaking longer doesn't do much at all. When the bubbles stop, the wicks are full.

I think the single longest burning fuel is "B100" BioDeisel. We got a 20 minute burn out of it on the right wicks last year. Should give you a better time. But honestly, 6 minutes is a LONG time to ask of pretty much any wick, let alone a hand candle. Have you thought of switching to an actual oil lamp? Take the glass part off these and you've got a 10 hour candle:
www.y2klanterns.com/html/mini.html

Plus, you can adjust the flame height to go for bigger fire and shorter burn.

have you considered swapping out fire tools in the song. my partner and i are working on a piece that it almost four minutes and we are layering what we do. i enter with palms and dance for a number of measures, she comes on with the small fans and lights off of me and we dance together, then i exit and she dances alone a few measures, then i come back and light the sword off of her and we finish together.

as for a longer burn, on my fire fingers which have a relatively small wick, to get them to burn longer i soaked in lamp oil then did a quick dunk in white gas to make them light faster as they were lit in the performance. i'm not familiar with the "B100" Biofuel for fire dance . . .anyone want to share info???

frankly i tend to keep ALL of my dances, fire or not, to four minutes or under . .. . unless you are super excellent versatile good i think you start losing your audience after that .. . they are ready to move on to the next thing. Audacity puts out a good free music editing program that might help you cut the music down to the parts you like best for a shorter performance/burn.

n

Get palm torches
www.flammaaeterna.com/p-938-p...hes.aspx
firewhip.com/bellydance.html