Oh, phooey...I wanted to imbed video in this post but time and incompetence have gotten the best of me...so here's the info in verbal form and perhaps someday I'll manage a video redux.
Previously, I've written how paint looks and behaves on the palette and what value to expect once it's put to paper. To recap: Runny paint (paint that moves freely on a tipped palette) makes light to medium value marks. Paint that moves slowly on a tipped palette makes medium to dark value marks. Paint that stays put makes the darkest mark available from that pigment.
So, with the right color in brush, the next challenge is to get it on paper with the desired appearance.
Watercolor doesn't like to be dabbed, stroked or brushed...it's mostly water and water likes to flow.
Think like so: The water carries the color and you move the water. You lead it where you want and after it evaporates, beautiful color remains....or not.
If you dab, stroke or otherwise nag it, watercolor leaves a mess. Lead it about nicely and it will gift you with colorful presents.
Runny paint and slow moving paint require different application procedures - but neither involves rubbing, scrubbing or dabbing.
Runny paint flows across the paper easily. If your paper is at a 45-60 degree angle it forms a juicy bead at the brushstroke's lower edge (the flatter you work, the faster the water soaks into the paper - it has to be on the surface to lead about). If you touch a loaded brush to the bottom edge of your bead you can continue to lay a smooth wash wherever you lead that bead. When you OVERLAP the bead with your brush, you risk streaks. Bringing your brush into an area you've just painted does a couple things: it can "wipe" a bit of the previous stroke away, leaving a lighter patch. Or, the additional liquid may wash the area lighter. I like to say "bring the brush TO IT but not THROUGH IT". The bead waits for you while you apply color to other areas, so don't run your brush out and leave a dry edge. Leave a bead so you can pick up where you left off. Just reload your brush, pick up the bead from underneath and lead on. When you get where you're going, "drink up" any remaining bead by touching a squeezed out brush tip to it.
WASH TIP: Keeping the brush handle pointing up lets gravity aid the release of paint. Pointing the handle down slows that release as gravity pulls it back into the tuft. If your bead starts to starve out, go "handle up" to keep it juicy. If you're coming up to a complex shape and need to paint around it with care, go "handle down" to slow the flow.
Slow moving paint is trickier to lead about because it's thicker. It won't form a bead you can coax along. So how do you get a relatively smooth application over large areas? Again, "bring the brush TO IT but not THROUGH IT".
Put some slow moving color on the paper - as far as it will go and still look wet. It should glisten. Then, reload your brush and bring the brush to the WET EDGE of the previous mark and let hydraulics do the joining. DON'T STIR BACK INTO PREVIOUSLY PAINTED AREAS to blend the new paint unless you want streaks, texture or blossoms.
1. HARD PAINT: Make sure the paint in the palette is fresh or re-moistened enough to get the desired consistency.
2. MIX PLENTY: Have color ready so the bead or wet edge isn't drying up while you mix more. Often painters try to cover too big an area and then starve their bead, or let their wet edge get too dry. While they're mixing more color - which is difficult when there's little of the original to go by - a hard edge forms where they left off. Then, they torture and scrub that distinct line trying to get the new paint look like a seamless extension of the old. The result is usually blotches and bands.
3. DON'T DILUTE: Another no-no is trying to extend the paint by bringing more water to it. That only lightens the mix you worked so hard to get right.
Remember: The trick to getting a smooth transition is to keep the bead - or the edge - wet!