perhaps the technique might be useful also for those not browsing through the artists´ sketchbooks;
I am sorry for my English - hope everything makes sense,
hope you can see all those *gifs/*movs playing ok -
and - hope you´ll enjoy :)
Photoshop: "Dry/textured" watercolor technique
>> alenah´s "watercolor511" brushes (download here) (http://www.ahdesign.cz/images/00/511/alenah_watercolor511%28set_of_3_brushes%29.zip)
(it is a "tool" *tpl preset file - zipped - if you are not sure how to load brushes into Photoshop, please have a look at the instructions here in my sketchbook (http://forums.cgsociety.org/showpost.php?p=5336385&postcount=134))
About the digital watercolor technique in general
Painting watercolor in digital - you can use a bunch of different techniques, different brush settings - and - different approaches.
The technique I used this time is kind of "dry-looking" textured watercolor style, that can be achieved with only ONE brush actually; the different look of the strokes is just different settings (lets call it "variants") of the same brush.
In my experience, Painting watercolor in Photoshop is not that intuitive (and does not look that natural) as in Painter; in PS the technique is a bit more technical (for me; compared to Painter), kind of "constructing" the image rather than really "painting" it, I would say ... anyway - you can achieve pretty decent "watercolor look" in Photoshop too.
In fact, also in PS you can get a really "believable/convincing" watercolor painting, when combining the brushwork with some more other techniques (adding "real-salty" textures, exaggerating/sharpening edges, blending separate "washes", adding more random dabs/"splashes" to it etc.) - but - I wanted to keep the technique/illlustration as simple as possible, so - this time - I did not combine the brushwork with any other techniques mentioned.
So - what is it that makes the painting look "watercolor-like"? The brushes - of course - but actually - the brushes are only one part of the whole process; there are a few more issues that affect the possible results quite a lot - and - when using watercolor brushes in an "incorrect" way, the painting may result in completely "non-watercolor look", very easily
So - what is it that makes such a difference?
There is a few things to keep in mind while painting digital watercolor:
The most characteristic feature of the watercolor painting is the transparency. In real media the transparent washes are subsequently building-up the image, usually from light to dark. In PS this can be achieved by lowered opacity/flow combined with the Multiply blending mode (set for a Brush in the upper Property bar, and - in case you work in more layers - set also for those layers in the Layers palette), that allows the strokes to build-up (multiply) the paint in the overlapping areas.
Placing the strokes
In order the multiplying effect can be achieved (so as the "building-up" effect can be visible) it is necessary to paint with more single/separated strokes (that is: several times over the same area to allow the strokes to overlap) rather than painting the way "click and drag" across the whole area you want to paint ..
(note: in order this feature can be applied/used, the pressure & tilt sensitive tablet should be installed on the computer; I use the Wacom Intuos 2 A4+ tablet)
All the brushes I used have a certain degree/quality of "tilt sensititivity" applied to it (defined in the Shape Dynamics dialog within the Brushes pallete): the basic 01 stroke is very slightly "tilt-sensitive", almost not responding to the tilt/position of the pen; the 02 texturizing and 03 stroke brushes are pretty sentitive to the tilt/way how you hold the pen while painting.
Using Pen Tilt feature requires a bit of experience, since its behavior may be a little bit "unpredictable" for the "first-timer"; the reason is that this feature makes the stroke "shift" off center/off the cursor position while painting (accordingly to the tilt scale/direction, if applied; the more tilted, the larger shift/distance/spread of the stroke is visible, and vice versa), which may be a bit confusing; but - after you get used to it, you can have perfect control over this type of strokes, allowing you to achieve a huge variability with only one brush variant ...
For this type of strokes Photoshop needs more time to calculate it, so you might experience some delay while painting larger areas.
It is also a good idea to apply the strokes repeatedly, with different tilt/pressure over the same area; so as you can achieve nice and pretty natural texturing (when the tilt is a wide/large angle, the painted stroke/texture is almost not visible, which might be sometimes very useful for subtle texture painting).
The speed of your hand movement while painting makes also a great difference, it is a good idea to paint pretty slowly while texturing, but - when painting the lines, easy quick energic strokes - repeated several times over the same area - result in much more natural, nicely "dry-textured" lines ...
There is a few more/other little things, that may affect the look of the strokes (sequencing/repetition of strokes, layers order, using "white strokes" combined with Overlay blending mode for "washing out" the color etc.) but - those are not that fundamental ..
I recorded a few real-time demos (*mov), showing/demonstrating the brush behavior under different circumstances/different way using them; you can download the *mov files below: (some of them are very small/short, some are little larger; downloading may take a while)
>> basic demo (1,6 MB) (http://www.ahdesign.cz/images/00/511/20_3_alenah_watercolor511_brushes_basic_demo.mov)
>> tilt demo - you can have perfect control over the stroke (2,1 MB) (http://www.ahdesign.cz/images/00/511/alenah_watercolor511_brushes_demo%28tilt%29.mov)
>> vertical x tilted pen effect (300 kB) (http://www.ahdesign.cz/images/00/511/alenahs_watercolor511%20ps%20brush%20demo%20%28pen%20tilt%20effect%29.mov)
>> one stroke variant, different effects (pen tilt feature applied) (300 kB) (http://www.ahdesign.cz/images/00/511/alenahs_watercolor511%20ps%20brush%20demo%28perfect%20control%29.mov)