I was just reminded that many of you don't know that you can apply Masking / Frisket to damp paper for softer edges. Some will work better than others - I like Pebeo. Other products may have a tendency to adhere to the paper while drying. I use this technique all of the time in my "Treasures from the shore" or "From the Sea" workshops in Point Reyes and Mendocino.
The trick is how wet the surface is when applying the masking or it can look like a blob. You can see an example in my book "Watercolor Essentials" from North Light or go to my fan page Birgit O'Connor Watercolors - photos pg. 2 Mendocino 2010 (look for the demos of rocks on the wall)
Some masking / frisket brands suggest NOT to use it on damp paper, that is why I like Pebeo - it works great!! I have never had any problems with it... I have had students use other brands without any problems but it is good to keep in mind that the brand may make a difference I use this technique on Arches paper so try a test first if using something else.
Where to find it: Cheap Joe's, Dick Blick, ASW, Jerry's Art-O-Rama and maybe some local art stores official name is Pebeo Drawing Gum :)
tip: - just like anything else how damp the surface is will really make a difference to your success :)