I always use watercolor paper for these, but I will use anything from the nicer 140lb coldpress to just a sheet from a cheap discount store watercolor pad. I typically make these background papers in batches of 3-6 pages at a time in maybe one or two color variations, on days when I am bored or don't have any other pressing projects to do. (Some days just scream "make backgrounds!" you know?) Then I have a nice stock of papers to go to when I need to start a new project later. (I also do the BGs for several pages in my journal books at the same time, since I already have the stuff out. It's nice to open the journal and have a whole bunch of pre-colored pages to work on)
I assembled the supplies I'll be using and laid them out on newspaper:
Sheet(s) of watercolor paper
Assorted watercolors - tube paints, watercolor cakes in regular and metallic (Coloriffic Metallic Shimmering Watercolors are a poor-mans Lumieres / Twinkling H2O's!)
Paintbrushes - I'm using the 1" hardware store nylon bristle type for the tube colors, and a smaller half inch brush for the cakes
Pan of water and small spray bottle of water
Cuppa salt! I only use kosher salt (the kind you cook with) though probably sea salt or any course salt would work too. You can try table salt but I think all you'll get with that is some pretty sandpaper ; ) WHICH! could be cool in a project too, so - I dunno, try it!
I start by wetting my entire sheet of paper by spritzing with the spray bottle then spreading it with a brush. I apply my chosen colors either straight from the tubes onto the paper or (in the photo shown) by using the pan colors that have been pre-wetted. I just randomly add color with the brush in an abstract fashion, sometimes adding a bit more water, and letting the paints run and bleed into one another until I have the mix and coverage that I want. *With the direct from the tube method, I squirt small dollops of paint randomly about the page and then work them together and into the paper with the brush. I usually let this stage get jussst this side of dry, then I take the spray bottle and spritz a bit to add droplets that will bleed and blend the colors even more. THAT itself will add little waterspots (you can vary them by applying the spray in a fine mist and larger splat-drops - sometimes I get it dowright wet, just depends on my mood really) and if you want you can stop here and let it dry and that will be a very fine BG paper
But I like to get a much more marbled, waterstained effect so this is when I add my salt - while the paper is still a bit damp - just sprinkling small handfuls all around, 'til I'm satisfied with the amount. The salt crystals wick up the remaining "pools" of water, along with some of the paint pigment, in whatever little spot they were sitting. Wait until the paper is totally dry, then brush all the salt off and voila! what's left behind is a neat bunch of little dotted areas where the salt "ate" the paint & water, giving your page a dappled look, and refining and melding some of those areas where your paint colors met and maybe didn't look so blended before.
Here's the end result on the pages I made that day, including one in a journal (that one I didn't salt but used alotttta water in the paint and just let it pool up together - came out pretty cool) Be sure to click on it to view it at fullsize so you can really see the details.
This is my ALL TIME FAVORITE page background making technique, and I hope you enjoyed reading it (or at least understood what I was saying!) and are ready to get out your art supplies and make some BGs of your own ... Have fun painting!
~ gem ~