Fundamentals of oil painting


Understanding the differences

So you want to do some oilpainting in Clip Studio Paint? Well thankfully Clip Studio is equipped with an incredibly versatile paint engine, allowing for all sorts of looks when drawing.

But the best brushes, tools and settings in the world won't help you achieve the oil paint look, if you don't understand the fundamental differences between traditional oil painting and digital painting.

In this tutorial I'll explain these differences, hopefully allowing you a more complete understanding of exactly what you are trying to emulate, resulting in a more accurate approach when aiming for this look. Let's get started.

The main differences between traditional and digital painting lie in three areas: The canvas you are drawing in, the tools you use to draw on the canvas, and the colours at your disposal.

Let's start by taking a look at the canvas itself.

The canvas

The main difference between traditional and digital painting is that in traditional painting your canvas is made from, well, canvas. When you paint, some of the uneven surface of the canvas will always show through, adding a certain imperfect quality to it.

In digital painting however you are painting on a perfectly flat surface, a digital grid storing pixel values. There are no imperfections, colour will always look the same, no matter where it's applied on the digital canvas. There are possibilites to apply textures to your brushstrokes, and the results are very similar to what you'd find on a traditional canvas, but it's good to keep in mind that there is a difference.

In digital painting the source of the texture is usually the brush, but not always - there are ways to introduce artifical texture to the canvas. For this we need to open the material window.

Clip Studio comes paired with some default textures for this. The most obvious one to choose would obviously be "Oil paint", but as I mentioned already, the actual texture in oil painting comes from the canvas you are painting on, so "Canvas" is also a good choice.

To add the texture to your painting drop it on the canvas and resize it to whatever level of detail you want. The layer should be above your actual painting in the layer order, and the blending mode set to 'Darken'. The reason for this is simple: Unless the paint itself is extremely opaque, it's unlikely to see colours which are brighter than the actual canvas they are placed upon. The white of the canvas should be the brightest thing in the picture.*

Obviously the texture we chose is rather dark, so we can't use it at 100% opacity and should make it a bit more transparent. Some value in the range of 5-15% is good.

I suggest turning this layer off during the painting process however and only re-enabling it after the painting is done, as the grey can muddle any colours you sample using the colour picker tool.

*(there are exceptions to this rule - there are special highlight paints in traditional painting, which are so bright, they make the white of paper or canvas look grey in comparison. This however is not the rule - we'll come back to this later in the tutorial.)

The colours

In digital painting we're used to the luxury of a full RGB colour-space with literally millions of colours, all of which can be chosen at any time, in any hue or value.

This luxury doesn't exist in traditional painting - paints are expensive, and as a result having every hue at your disposal is not realistic.
Another thing to keep in mind is that when people talk about the 'oil painting look', they often have the paintings of old masters in mind. But chemically produced paints are a rather recent invention, and as such, the old masters wouldn't even have the option to buy all hues of colour as paints, even if they had the money for it. Some hues simply didn't exist as ready-made paints.

Instead it was (and still is) common in traditional common to mix your own paints. You start with the elementary colours (red, blue, yellow) and mix then into other colours.

It's important to note however that the elementary colours for pigments and light are different. In paints they are red, blue and yellow. This differs from light, where they are red, green and blue (hence the RGB colour-space which is widely used on computers).

Thankfully Clip Studio's paint engine is set up to emulate the traditional colour mixing by default, so there's nothing we have to change there. Mixing red and green for example will result in a brownish colour, as one would expect.
(If it were set up according to the light mixing rules, mixing red and green should result in yellow.)

To get closer to the traditional way of mixing and matching colours yourself, it's a good idea to stop using the color wheel while doing oil painting and instead switch to a limited palette. You can find the colour set window by clicking on this tab next to the color wheel.

Even this limited colour set provides you with a lot more colours than you'd normally have at your disposal in traditional painting - it's a good idea to play around with the various available color set, look for one that fits your needs online, or set one up yourself to fit the mood you are trying to go for in your painting. But there are already various tutorials on how to choose good colours for your drawings out there, so I won't repeat this information here.

The brushes

As mentioned in the 'canvas'-section, the main source of texture in digital painting is the brush. Instead of an uneven surface that influences the way paint is sticking to the canvas, digital brushes basically project a texture with every stroke - and if we try to emulate traditional oil painting, the projected texture obviously needs to be something we'd expect in a traditional painting: a canvas texture.

Clip studio comes with various oil paint brushes, but none of them fit our need for a realistic brush exactly. We could obviously choose one of the many brushes in the Clip Studio asset store, but for this tutorial we'll instead create a brush of our own - hopefully deepening our understanding of the brush engine in the process.

We'll start by selecting the brush tool, switching to the oil paint tab and duplicating one of the existing default brushes.

Next we go into the sub-tool options to modify the shape of the brush tip - the default brush is a bit too round and even for my taste. Remember: traditional painters use real brushes with bristles, which are obviously a lot more uneven.

We click on the small wrench icon in the tool property panel, click on the 'Brush Tip' text in the Sub Tool details, and change the tip shape from 'Circle' to 'Material'.
Next we click on the 'add brush tip shape' icon and select an appropriate material in the window that opens up. I choose the 'brush' image material that comes bundled with Clip Studio by default, and confirm my selection by pressing 'OK'.

The difference is immediately apparent: the upper brush stroke is from the original unmodified oil paint brush, the lower brush stroke is after changing the brush tip. But the result still looks a bit too artificial in my opinion - so let's dive deeper into the brush settings.

Let's switch to the 'Stroke' setting and change the Gap from 'Fixed' to 'Narrow'.

In this image you can see what the stroke would look like for each available option.

Next we switch to the 'Texture' setting and select which image to use for the texture (I chose the 'Canvas' texture which comes bundled with Clip Studio by default).

With the default setting the texture is barely visible, so it's a good idea to play around with the 'Scale ratio' setting for a bit.

In the picture above you can see the resulting stroke for various values of this setting (you might need to look at the full-size image to see the differences)

Changing the 'Method to apply texture' has far more obvious differences.

Checking the 'Apply by each plot' checkbox changes results even further. I personally prefer the look of the 'outline' option, but basically all options look great (just different). You could even think about creating various brushes which differ in just this single setting for various looks.

Next we switch to the 'Ink' setting to play around with the 'Color mixing' option.
Clicking the 'Blend' icon results in a wetter look, while the 'Running color' icon results in a dryer look, where the paint doesn't mix as much. Choose whatever option fits your needs better (or create two brushes with different settings). I personally choose the 'Blend' look.

After that we play around with the 'Amount of paint' setting by entering different values. In the picture above oyu can see the result of various values.

This setting is basically supposed to emulate how much deep you dunked your brush into the paint. The more paint on the brush, the less it matters when you brush over some other colour.

This is however not the only option that influences how the colours mix. I suggest picking a high value here in the 60-90 range, and influencing the mixing in the next setting.

The 'Density of paint' option influences how thick the paint is. The lower the number, the more the colours below will show through. For realistic mixing I suggest a value in the upper mid-range (50-75).

The 'Color stretch' setting influences how much paint the brush picks up from the canvas. In this example I use a brush with the colour red, and start the stroke by initially pressing into a blue speck of paint on the canvas. The higher the 'Color stretch' value, the farther along the colour gets dragged along, before the actual colour of the brush starts to show through again.

I suggest a rather low value here (5-15)

Once you are happy with your settings, remember to click 'Save all settings as default'.


Another difference between traditional and digital painting is the existence of layers in digital painting, which is obviously absent in traditional media. Once something is painted on the canvas, there's no way to draw behind it. If you are trying to emulate oil painting digitally, it's a good idea to keep this in mind and keep the use of layers to a minimum.
There are times where you might still want to use layers, as they are exceedingly useful, but there are some things to remember, as to not destroy some of the side-effects of only having one layer to paint on which has a huge influence on the look of traditional oil painting.

One of the 'legitimate' uses of layers is to simulate letting a painting sit until the paint is dry.
As long as paint is wet, it would obviously mix, resulting in colours blending together, which at times it wanted. But sometimes are certain part of an image can be considered 'finished', and at those times it's useful to lock the results in, by starting a new layer. Once you are painting on a new layer, Clip Studio won't consider the lower layers for it's colour mixing options of the brush.

In digital painting it's no problem to insert some background elements into the painting at some later point. Simply paint whatever you need on a new layer and move the layer down in the layer order.

Things however aren't as simple in traditional painting.

As all paint is applied to one canvas, there is no option to 'paint under' something. Anything you'd want to add to the background in traditional oil painting would need to be painted on top of everything, and you'd have to try your hardest to simply paint around anything in the foreground that you wanted to preserve.

This is obviously rather tedious and often results in imperfect results - but it's exactly these imperfections that make up one of the core quality of traditional painting.

So if you want to simulate traditional oil painting in Clip Studio, I suggest to not fall into the temptation of using too many layers and adding things into the background at points in time where it would no longer be possible in traditional media - instead embrace the imperfections and paint on top of things you already painted. The extra time you have to spend on the silhouettes of foreground objects will have visible impact on your brushstrokes and where they are placed on the canvas, giving them one of the core qualities one would expect from a 'real' oil painting.

Thick layers of paint & bringing it all together

As mentioned in the beginning of this tutorial, one of the core qualities of traditional media is the texture of the canvas, which is still visible through paint applied to it.

But another source of texture is often forgotten and neglected: The paint itself.

Any and all brush strokes add paint on top of the canvas, slowly building up layers upon layers of paint, which slowly even out the roughness of the canvas below, until eventually the texture of the canvas itself becomes barely visible.

Some especially experienced oil painters make use of this quality, to use the texture of paint itself to influence the look of the resulting image, using thick layers of paint in some areas to conceal the canvas, while letting the texture shine through in others.

We can simulate this technique by separating our layer structure into three distinct areas:

Our painting at the very bottom, our canvas texture in the middle, and a layer for a few select carefully planned brush strokes that we want to emphasize on the very top.
For these brush strokes at the top it's suggested to use a different brush (e.g. the brush we created but with the texture setting disabled, or the default oil paint brush), to emphasize that no canvas texture shows through on these brush strokes.

In my example you can see that the base painting takes up the entire canvas, as does the canvas texture above it, but the brush strokes are only in a few select places, which I want to highlight by giving them a thicker paint texture, preventing the canvas texture from shining through.

And there you have it, all the techniques you could possibly need to emulate the look of traditional oil painting in Clip Studio Paint!

I'm afraid my example painting can't keep up with the old masters, but I still hope that I managed to share some useful knowledge with you.

Enjoy your painting!


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