There are some characteristics of watercolor paint (and, to some extent, dilute acrylic paint) that are quite unique. These are its transparency; the surface-tension effect that results in fine, crisp edges; the flowing of the paint, that results in pooling at the bottom edge; the mixing of the paints on the paper when wet paint comes into contact with wet paint; the way that the pigment can separate out and settle in the hollows of the paper; and the way that the paint dries lighter.
These effects can be both wonderful and terrible, and there are plenty of paintings that are ruined because flowing paint has turned to mud, edges appear where they are not wanted, a smooth surface ends up with a granulated look, and so on. But either through luck or by controlling the medium, watercolors can have a luminosity and lightness that is very difficult, or impossible, to replicate using other media.
In this article I will discuss these different characteristics in a bit more detail, and at the same time I'll explain how the same, or similar, effects can be achieved using Photoshop (and also how some of the less desirable characteristics are avoided in Photoshop).
Watercolor paint is made up of pigment which is dispersed in a medium or vehicle. The vehicle is composed of a binder (usually gum arabic) and water. There are also some other ingredients to help the paint retain moisture, etc. The paint is then mixed with water before being applied to the paper. The paint has a degree of transparency because of the added water; also some pigments are more opaque than others, so the transparency will vary between colors. At any rate, all watercolor paints will to a lesser or greater degree allow the underlying paper to show through.
This is one of the key things that gives watercolors its characteristic variation of tone and its lightness and luminance.
Varying the transparency of the paint in Photoshop is achieved simply by varying the brush (and/or layer) opacity.
Because of this transparency, it's possible to apply several layers of paint one on top of the other. If the pigments and colors are carefully chosen the result can be very beautiful, giving great subtelty of tone and color. Here is an example of red paint and blue paint applied over yellow paint.
As you can see, the red and yellow give an orange hue while the blue and yellow give a green hue.
To achieve this in Photoshop is very easy ... all that is required is that the overlaid paint be applied on a new layer with its blend mode set to Multiply. This is exactly equivalent to putting paint down on paper, letting it dry, then putting more paint over it.
Because of the transparency of the paint, and because it is applied diluted, the texture of the paper will show through, as you can see in these examples. This can give a lovely effect, but of course it can be avoided if it isn't wanted: in traditional painting simply by painting on a smooth paper, or by applying a gesso wash to the areas of the paper where this effect is not wanted, and then painting over it; in Photoshop by using a hot-press background layer, or by deleting texture where it isn't wanted.
A side-effect of the paint's transparency is that, in general, white paint is not needed: instead, the white is the paper white: so if you want an area to be white, you simply don't apply paint to it. Varying the tone of the color is achieved by adding more or less water to the paint (whereas in other media it's achieved by adding black or white paint to the color).
In Photoshop, the layer blend mode should always be set to Multiply for watercolor layers. This makes the layer transparent and so the paper white, on the background layer, will show through just as it does on traditional painting. White paint will then be invisible. If you want white paint to show, simulating gouache, for example, then the layer blend mode should be set to Normal.
When dilute paint is applied to dry paper, as the paint dries it tends to flow towards the edges. This results in a fine edge which is darker than the main body.
Here is an example of the sort of edge possible:
The top image has no edges applied to it; the next one down does. The strength of the edges can be reduced to nothing or increased considerably, simply by varying the opacity of the edge layer. As the edges are on a separate layer, we can mask them out so that they are only visible where we want them.
You can also see that the paint at the top of the images has been allowed to bleed into the surrounding paper (which is a wet-in-wet technique), so that there are no edges seen there.
Different types of edges are possible with the PaintingDigitally toolset: normal, strong, rough and wide.
Pooling is when wet paint that is applied to dry paper is allowed to flow downwards towards one of the edges.
The top image has no pooling effect applied to it whereas the bottom image has, using the MakePooling action. The width and strength of the pooled paint, as well as where it occurs, can be easily controlled.
All sorts of effects can occur when we drop or add paint to wet paint. This depends on the pigments, whether we just drop the paint in or mix it in, how wet the paints are, how wet they are relative to each other, the slope of the paper ... and so on.
The two can just mix gently, resulting in a third color; one paint can flow quite rapidly into the other (the wetter paint will flow into the drier paint) producing artifacts like blooms or cauliflowers; edges and pooling can occur as the paints dry; the added paint can lift and carry the underlying paint; and plenty of other effects.
These effects can be simulated in Photoshop, a bit like how a skilled traditional painter would do it: the effect that is wanted is known and how to control it is known. It isn't the sort of random effect that a less skilled painter would 'achieve' ... a lucky accident in other words, because with Photoshop the effect is not random, but created using the brushes and blenders. Having said that, some of the blenders have a considerable amount of scattering, and as a result the effect isn't precisely controlled.
The examples here demonstrate some of these effects. The middle image shows the sort of gentle blending that can happen when the two paints are at about the same wetness; the top example shows the added paint spreading in a more granular way, and it also shows what can happen if a drop of water falls on the paper; the bottom example shows the added paint dragging the underlying paint towards the edges and creating an edge; it also shows the added paint running down the paper and carrying the underlying paint with it.
The possible effects are endless ... adding a third color, for example, will result in all sorts of interesting color blends and bleeds. At any rate creating these effects is entirely possible using the PaintingDigitally tools in Photoshop.
When the brush has been loaded with just a little paint, or if the paint is very thick, the paint won't flow into the hollows of the paper as it would when the brush is fully loaded with wet paint. The effect is typically as shown here. There are many possible effects ... it's just a question of knowing what you want and picking the right brushes.
Dry on dry painting can be very useful for textures.
Of course the paint can be applied on existing paint: in that case, if the underlying paint is fully dry the effect will be something like the bottom image on the left hand side. If the underlying paint is still a bit damp, or if the pigment isn't a strong staining pigment, then the effect may be more like the bottom image, right hand side, where there is a bit of mixing and blurring.
Lifting off is a technique in traditional painting where slightly damp paint is lifted off using a dry brush, piece of paper etc; or dry paint can be wetted and scrubbed a bit, then lifted off with paper or a cloth. The same thing can be done in Photoshop, but much more easily, using erasers.
The most basic erasers simply remove the paint completely, which isn't normally what one would want to do (although it's an alternative to masking off). Instead some of the paint needs to be left behind, typically as shown in the examples here.
Right at the bottom of the image I've used a soft eraser which has leached out the color (I mention it here because you may well miss it!). The other erasers are self-explanatory, I think. By varying the pressure of the stylus and/or the opacity of the eraser, more or less paint can be removed.
If salt crystals are dropped onto slightly damp paint, the salt will absorb the paint, leaving a white spot. The same thing can be achieved with the PaintingDigitally tools by using the Scratch Brush action: this sets up a non-destructive layer and selects a brush that can either be used for a salt-type effect, or for scratching the surface of the paint.
Paint can be scratched off the paper in all sorts of different ways: using a nail, knife, sand-paper etc. The lifting-off examples above are effectively the same thing. In this example I used the Scratch Brush action to achieve an effect like sandpaper. The advantage of this technique is that the scratching is non-destructive, so it can be removed where it is not wanted, as I show in the center section. (A matter of the eraser erasing the erased ).
This is just dropping blobs of paint or water onto dry paper. In traditional painting we normally use a brush well loaded with dilute paint or water and flick the brush with a finger so that drops of the liquid splatter onto the paper. Depending on the angle of the stroke the drops can be round or elongated.
In Photoshop, there are three splatter brushes that give the sort of effect shown here. One big advantage of Photoshop, once again, is that unwanted splatters can be removed.
On this image I'm also showing some watermarks. This effect occurs when a drop of water falls onto dry or semi-dry paint: it will lift the paint and carry it to the edges of the drop, resulting in an edge, as shown. A Make Watermark action creates a new layer and selects the watermark brush: this means that the effect is completely non-destructive, so the watermarks can be resized, moved or removed.
In traditional painting we normally try to avoid blooms, or cauliflowers, like the plague! ... but they can be used to good effect too. They usually happen when some wet paint or water is splashed onto drier paint, or when some wetter paint comes into contact with drier paint, as shown here, with the yellow paint flowing into the blue paint, and also with the drop of water spreading into the blue paint.
In this case the paint ended up with a raggedy sort of edge like a cauliflower, but it's also possible to end up with quite a smooth edge.
With the PaintingDigitally tools, blenders are provided to produce these effects.
Some pigments tend to separate out and settle into the hollows of the paper, giving a grainy effect which can be lovely.
There are several ways to achieve this using the PaintingDigitally tools, some of them non-destructive (the example at the top) and others destructive (as shown in the lower image).
Both give a lot of control ... and even with the destructive technique we can always hit the undo button! One of the great advantages of digital!
I've provided quite an extensive set of brushes for mixed-media work: gouache, pastels, gesso, ink, chalk and charcoal (as shown here).
Some of these brushes are not available in the current release of the tools (version 8) but I will release them in version 9.
This is an area that Photoshop excels at over traditional painting. The imagination is really the only obstacle to what can be done.
In this example I show various textures applied to a simple painting. In this case, the only thing that I painted was the pot, flowers and fruit. The lines on the pot come from a pattern and the window and background come from a photograph (I just pencilled in some lines to give a painterly effect). For details on how I've done this, please have a look at my video on Patterns and Textures.
I hope this article will inspire you to have a go!