I just wanted to mention that the OP here from Randy Ryan, even 12 years later, is still one of the best ways to do a traditional dope finish that can be found on this or any other modeling forum. I follow it pretty closely on all my models and it hasn't let me down. It's printed out and hangs on my shop wall.

Straightening warped balsa is quite easy in must cases. First soak well with clear water, hot water speeds the soaking process. Remove from water and straighten the piece by flexing it opposite the warp. When it is straight suspend vertically and let dry thoroughly. I have done this many many times and never had it fail.