Real Watercolor Deposition vs. Flow

How time flies when you spend it with a new baby :)  After a wonderful parental leave, I am happy to be back at work this week.  And for my first blog post in several weeks, I decided to write about a topic that I think can be a bit confusing sometimes: Real Watercolor Deposition vs. Flow.

When you paint with the new Real Watercolor media in Painter 12, there are actually 2 very distinct painting models happening: deposition and flow.

  1. Deposition
    In this model, some media is transfered from the brush onto the paper surface.
    *You can have brushes that only do deposition without flow... these would be dry watercolor brushes
  2. Flow
    In this model, the media already on the paper surface flows and spreads on the surface and into the paper.  
    The flow process will continue until all the water is evaporated, absorbed and the pigment is settled. 
    *Flow can't happen without having deposition first.
As you can imagine, Painter provides brush settings to control how each of these models will behave.  

For instance, in the deposition model, you can control such things as:

  • Brush wetness
  • Pigment concentration (on the brush)
In the flow model, you can control settings like:
  • Evaporation rate
  • Paper roughness
  • Wind strength
Changing settings that affect the deposition process will have no effect on how the media flows and vice versa.  Of course if you deposit more water in the deposition process, then more water will be available to flow, so there is a link between the 2 models.  But the controls themselves are independent between the deposition and flow models.

*** Changing flow settings while media is still flowing ***
As I mentionned, flow controls affect media on the surface that is not completely evaporated or settled.  This means that while the media is still flowing, you can change flow controls to dynamically change how the media flows.  This way, you can visually see the live impact of the flow controls on the flowing media.
Because flow controls are stored with the brush, there is an important side effect to consider. If you switch between two watercolor brushes, having different flow settings, and you do this while the media is still flowing, you will actually change the result of your brush stroke.
This is because if you switch to a brush with different flow settings, these flow settings will apply to ALL the currently flowing media that was deposited, even if it was deposited with another brush.
You can always wait for the media to finish flowing before switching to a different brush if you prefer.
*** Deposition controls ***
For this blog post, I will briefly describe the deposition controls. In a future blog post, I will cover the flow controls.
As I mentionned above, the settings that control deposition have no impact on how the media will flow or settle on the paper.  These settings ONLY change how the media is transfered from the brush to the paper.
The settings that control deposition include:


  • Brush Wetness: how much water is on the brush (and how much will get transfered to the surface)
  • Pigment Concentration of the media on the brush (this controls the concentration of the pigment that gets deposited from the brush, not the concentration of the pigment as it settles during the flow process, that would be another control called Settling Rate)


  • Dab shape and profile (and related controls such as Angle, Squeeze, Static Bristle, Hard Media etc.)
    This will control where and how much of the media gets deposited. 

  • Method of deposition (again, this only affects how the media, water and pigment, gets deposited from the brush to the flow surface, what happens during the flow process is independent of this setting)


  • Opacity - Controls how much media is deposited
  • Grain  - Controls pigment concentration as it is deposited (pigment concentration follows the grain pattern).


    Note that these settings can be hooked to Expressions (such as pressure or velocity), which is a good way of creating Watercolor brushes that respond to tablet expressions.  For instance, if you hook Opacity to Pressure, you can control how much media is deposited from the brush to the paper using pressure.

    Also, as mentionned, Grain affects only the deposited pigment from the brush to the paper.  There are other controls to control paper grain behaviors during the flow process (such as Granulation in the Real Watercolor controls).

For example, in the image below, only the Grain setting was adjusted between the 3 strokes.  You can see that the deposited media responds to the grain setting.  The pigment concentration of the deposited media folllows the paper pattern.  The flow process was paused to capture the image.

Then we let the flow proceed by unpausing the process:

Because the brush used in this example has some granulation in it's flow settings, some grain is visible in the first stroke, even though none was visible after the deposition.

I think this covers the most common settings that control deposition.  In a future blog post, I will review what settings control the flow and how they work.

If you have specific questions on the topic of Real Watercolor Deposition, or any other comments let me know :)

Happy painting!


  • Hey Chris...welcome back...'-}}

    Thank you very much for continuing to describe the nitty-gritty of how RWC brushes work. It's very, very helpful...

    What is the relationship between deposition, flow and the animation step settings?

    Is animation step purely visible in that it just displays the flow or does animation step impact in any way the end result of the flow settings? My guess is that it does not impact deposition at all?



    PS: you've misspelled "independEnt"...'-}}

  • Hi Terrie,

    thanks for the feedback!

    To answer your question, animation step only affects flow "animation speed".  It does not change the end result of the flow.  And it does not affect deposition.

    You can think of it as how much "flow work" you want the system to do between each rendering of the flowing area.  

    You might for example want an image update after each flow calculation. This would be a very smooth animation, but very slow.  This would be setting animation step to the minimum value.

    Or, for example, if you use a large step value, a lot of work will be done between each rendering.  The result is an animation that will be less smooth, but faster (because less time is spent updating the the current image).

    The extreme would be no updates while the system is flowing.  This would mean that you would see no intermediate image updates.  Just the final dried result.  This would not be as interactive because you would not see the paint flowing and drying.  

    Because every system is different, and because of the various brushes you can create, I decided to include a control for the animation step (speed).

    Thanks for the typo catch! I often get that word wrong because of the french spelling ;)



  • >>animation step only affects flow "animation speed".  It does not change the end result of the flow.  And it does not affect deposition.

    That's what I figured. I tend to set Animation Step to a high value--generally between 7 and 10--primarily because I have an older system and not much RAM (just 2GB).

    What would be VERY, VERY cool is if we could STOP the flow rather than just pause it because often, I see something as animation is progressing that I like.

    Given your description of the animation process my guess is that it might be tricky to code the Stop Process because it could be what I see on the screen is not in sync with the reality of the behind the scenes rendering process BUT! I could live with that because I figure I could tweak the Animation Step value to a lower number (slower) to "catch" what I see.

    Soooo...could you perhaps keep the idea of allowing the user to stop the flow process in the back of your mind??? Pretty please...'-}}

    >>Thanks for the typo catch! I often get that word wrong because of the french spelling ;)

    I wondered if that might be what was going on...'-}}


  • Hey Chris,

    So glad to see you back posting again.  I hope you still get plenty of time to enjoy that new baby.

    I have had the best time making papers and runny, drippy brushes since your post about using fractal patterns to make paper.  The results are truly amazing and I believe mimic traditional watercolor in every way.  Changing the brush controls in the middle of a flow is a great help as is the Dry Watercolor Layer command.  It is almost as if we are turning and tilting the tablet...and then hitting the paper with a hair dryer.  What fun.  

    Thank you so much for all the work that you have done on Real Watercolors.  They are the best.


  • Hi Terrie,

    I completely understand what you mean.  Sometimes, you "pause" the watercolor simulation and you would want to keep/dry what you currently are seeing on the document.

    There are actually a couple ways to "auto-dry" the watercolor to achieve this. One easy way, as suggested by Skip, is to select the "Dry Watercolor Layer" command under the "Layers" menu.  You can even create a custom palette with a button for "Pause" and another for the "Dry Watercolor Layer" command, if you find you would like to use this often.


  • Hi Skip,

    I have just seen some of the work you have done, and I love it!!  I am very very happy to see that you are making amazing artwork with the new Real Watercolor functionality.  Please keep sharing.



  • >>Sometimes, you "pause" the watercolor simulation and you would want to keep/dry what you currently are seeing on the document.

    Exactly! '-}}

    >>One easy way, as suggested by Skip, is to select the "Dry Watercolor Layer" command under the "Layers" menu.

    Hmmm...can I do that when I've Paused? Sounds like I can--given the idea of a custom palette--so I will have to try it...


  • Hi Chris,

    Thank you so much for the compliment about my work.  I hope you and the rest of the Corel Development Team know how appreciative I am...we are...of your efforts.  Y'all rock big time.



  • Hi Chris,

    Excellent article. I understand the Real Watercolor process better now.

    You mentioned you could create a button for the Pause, but I was trying to create a custom command and can't find where the pause is in  the menus?



  • Hi John,

    you are correct. My mistake.  You currently can't add the pause command to a custom palette.

    The only way to access it from the property bar or the brush controls panel.