You need to get a rare fountain faerie quest.
The rainbow fountain only works if you have completed a fountain faerie quest. If you have completed a fountain faerie quest, go to the rainbow fountain and you can paint your neopet any color except MSP, Royal, and Robot. Bori cannot be painted ice because the ice bori was a special "Hannah and the Ice Caves" release.
If you are referring to the Neopets Quests, these are random quests given out to users and may be completed for a chance to paint your Neopet at the Rainbow Pool.
The rainbow pool http://www.neopets.com/pool/ will tell you what colors each neopet can be painted.
By painting your pets at the rainbow fountain, selling the paint brush, donating the paint brush, or discarding it. If what you're asking is how to get the paint brush off after you have already painted your pet, you have to paint your pet again with a paint brush, rainbow fountain, a random event, and there's a chance that the lab ray will change the color of your pet.
You techinally don't "put" the brush on the pet. Go to shops, and then to the rainbow fountain...it will then let you select the brush you have and the pet you wish to paint. Make sure its what you want to do though, once you paint the pet the only way to change it is to repaint it or give it a morphing potion.
It only works when you complete a quest from the fountain faerie. After you do, you can visit the fountain and paint your pet any color you'd like. :)
Your pet turns the color of the paintbrush. Cool, huh.
yes
The Rainbow Fountain works on Neopets if you are a Neopets mod, or if you have a Fountain Faerie quest.
i dont know make a trade
paintbrushes
To paint a resin fountain, you need a paint that can adhere to plastic. Since it is for a fountain, you will also need paint that is waterproof. Many manufacturers make such paint, you just need to read the label to find what you want.