This is a free complex Vray shader for a realistic balloon.
The files (3ds Max 2010) contains the basic geomtry, the shader and all required maps. It is ready to render.
The complex shader includes transluscency and angle controlled opacity as well as multilayered materials and a subtle fingerprint glossiness map, all of which are included.
This material works on the provided geometry or on your own in all circumstances and will give realistic results in Vray 2.0 under all light conditions.
Enjoy and experiment