I get asked the same questions every festival, so I though I would break down some of the basics for you:
What happens when it rains?
You take cover! Really though, rain is a natural element that you deal with when doing street art. Obviously if its raining pre-event then a festival can be canceled, but mostly if it starts to rain all the artists just take cover and wait it out. When its done you return back to your piece, check out the damage, and keep going.
Are you sad knowing it is only temporary?
It's sort of a bitter-sweet art form. In a way it is sad knowing that the elements (or city) will remove it, but its also part of the experience. Street art is very much a performance art, and it really feeds off of the energy from the audience. Its a great way for an artists to get positive feedback from the viewers (and boost their egos!). Plus, my favorite part, is that everyone can snap a picture with there phone and they now have a piece of art that no one else will ever get to see in person.
Don't your fingers/knees/back hurt?
But really, you get used to it. Gloves help protect your hands and alot of artists use kneepads to help.
Do you get paid for this?
It really depends on the artist and the festival. Normally a "featured artists" who helps bring in other artists and views will receive some pay. Generally speaking most artists donate their time and talent for free; as a chance for exposure, to help out the event, and for the love of the art. A lot of people don't realize the out of pocket costs for a chalk artist. We travel to an event, eat there, and sometimes stay over night- all for you! Some festivals are really amazing and provide compensation/supplies/accommodations for artists. So if you see a "tip" jar, please do. Ever heard the phrase starving artists? We really do work for food.
How do you do it?
With chalk? Haha, this really is a tough question to answer. There are many techniques, but generally like everything else it all comes to down practice. Its pretty easy to learn how to chalk if you are familiar with other mediums, its all about color blending. Plus you have to be good with getting a little dirty.