Question regarding Van De Graff generator Belt I have made a VDG generator with a rubber band as the belt and a glass roller. It doesnt seem to work because I think the rubber band may be conductive.
I was thinking of using other materials for the band and the roller. Please tell me which pairs may work out.
Roller-           Band
1.Glass-           Rubber from a baloon
2.Glass-           Strip from a plastic bag
3.Human Hair-      Rubber from a baloon
4.Glass-           Silk
5.Glass-           Felt
 A: A wide rubber band should work fine.  Both the belt and the roller must be extremely clean.  EXTREMELY extremely clean.  A single fingerprint can be enough to mess things up, since the contamination distributes itself all over as the motor runs.   If your belt and roller aren't clean, then oil film is touching oil film, and no rubber actually touches any glass.
Clean the rubber in soap and water.  Then wear rubber gloves and scrub it with a couple of changes of rubbing alcohol.   Dry it completely (a warm blow-dryer speeds things up.)
Do similar on your glass roller.   Clean every tiny trace of grease, and wear gloves for the last stage of cleaning.
Of course the two rollers must be composed of different materials.  Try metal for one roller, or perhaps wrap one roller with aluminum foil.
PS
You can experiment with many materials by placing them over the surface of your glass roller.   For example, white teflon plumbers tape, you can stick down the end of the teflon using any tape, then wind it around to cover the entire glass roller, then stick down the far end of the teflon tape.
A good combination I found:  polyethylene grocery bag strip, and teflon plumbers tape on one roller.   (Use crazy glue to attach a strip of grocery bag in a circular band of just the right diameter.)
A: The best rubber material to use is pure gum rubber. Rubber from an inner tube (tire) contains carbon and balloons may have other colorants which are conductive and will not work well. A wider belt will carry more charge. The 'combs' or charge pick-offs at the base and collecting sphere should not touch the belt but come very close - about 1/16". The tube separating the top collecting sphere and the base should be nonconductive like clear acrylic or glass, and the larger the separation, the higher the voltage. Greater than 18" can get you up to 100,000 volts.
You can purchase gum rubber belts online for about 10.00 dollars from companies like Ginsberg Scientific (American Educational Products). They no longer show this on the website, but if you call I believe they still stock replacement parts for the machine they used to sell. Last year I purchased on of these machines for 99 cents on EBay and refurbished with a new belt and tube for less than $20.00.
Good luck on your project.
