Is your Van De Graaff generator not performing like it should? Has the output diminished significantly? I've put together some helpful tips and tricks below that will help you sort out any performance issues that you may be experiencing. Van De Graaff generators can be temperamental at times, so knowing where the trouble spots are can help make your demonstrations a success.
Make sure that you unplug the device prior to performing any maintenance tasks below. A thorough cleaning should be your first priority. Dust and dirt accumulations will rob the Van De Graaff generator of significant output. Clean the all surfaces with a paper towel and water. Avoid using towels from around the house that could have been exposed to dryer sheets. Dryer sheets contain oils that are designed to eliminate electrostatic charging. Clean all surfaces, including inside of the tube where the belt runs. Van De Graaff generator construction varies, so consult your manufacturer for belt removal information. I've found the best way to clean the tube is with a paper towel and a wooden meter stick. Do not use anything that will damage or scratch the inside of the plastic tube. Inspect the belt for damage or wear and replace as needed. Clean the belt using water and one TINY dollop of dishwashing liquid. Dry the belt using paper towels.
I've read suggestions on other websites about using talcum power, but I do not use nor suggest this technique. Microscopic pores in the rollers can be clogged with powder and electrostatic charging can be inhibited. I have also read someone suggest that "Over time the belt and lower pulley may absorb moisture" and that you should use a hair dryer to "dry" the rollers and belt. If you are in a humid climate, or if the generator has been stored in a moist environment like a basement, using a hair dryer to thoroughly dry the belt and rollers may very well provide a performance boost.
As your belt wears, so do your rollers. Most users don’t even give the rollers a second thought, and this is a terrible oversight! The rollers are after all, where all of the action happens. While the belt is off, use fine grit sandpaper to rough up the rollers, especially the lower one in the base. Sand the roller lightly in all directions while rotating the roller. Use a clean, dry paper towel to remove any sandpaper residue from the rollers. The rollers supplied by the factory are rough, and with use, the microscopic ridges and pores in the rollers are smoothed over time. More surface area means faster charging and larger electrostatic accumulations. You will be “shocked” by the increase in generator output after performing this simple step.
Don't forget to lubricate! Depending upon the Van De Graaff generator manufacturer, bearings may be employed in the rollers. Periodic lubrication of the roller bearings is required. Simply add a dab of light weight bearing grease to each roller bearing. Don't get carried away here, a tiny dollop of grease is sufficient. Use too much grease and the excess may very well end up on the belt or rollers, inhibiting electrostatic charging.