Wayne -

I am trying to learn the VDB process. My experience so far is that you definitely want to process immediately.

I have found that the process is rather erratic - so much so that I can't depend on getting a good print each time. Therefore, I need to process each print before deciding what I need to change before I attempt the next print.

My practice has been to coat several sheets of paper early in the morning, and then go back for a second application late morning. That gives me several hours for the paper to dry thoroughly before I start printing/processing in the afternoon.

I have also found that the process is VERY sensitive to the paper being using, and switching papers makes a really big difference in the quality of the final image. I initially started with relatively smooth water pads, then bristol illustration paper, and finally hot press mould-made watercolor sheets. I'll know better in a couple of hours how that works.