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A new watercolour artist asked me recently if it is okay that the pencil lines show through her finished watercolour painting. Like most questions beginners have - there is so much more to this deceptively simple question.

The short answer is yes - its definitely okay to have visible pencil lines in your finished watercolour painting. (Look for some famous  watercolour paintings by John Singer Sergeant and you will see the pencil marks. )

More importantly, it is okay to have visible pencil lines because of the golden rule of art - there are no rules. If you like your painting that way then that is validation enough.

Delightfully, there are many ways to go about sketching for watercolour painting.

Let’s figure out what pencil drawing approach will work best for you.

The role of pencil lines in watercolour painting

What role do you want the pencil lines to play in your watercolour painting?

This is probably the most important question for you to ask yourself. Once you figure out what you like, everything else can fall into place.

The truth is there is no right or wrong answer here. Pencil drawing and watercolour play very nicely together. Great results can be achieved with more reliance on pencil drawing or more reliance on watercolour or a good, even balance. All are valid approaches.

Watercolour over pencil art

If you are very competent at drawing with a pencil, or if you enjoy the fine details of a pencil drawing, this might be the approach for you.

You can essentially create a detailed pencil drawing and then splash in some watercolour. In this way, the artwork relies on the beautiful drawing and the watercolour takes a background role. So clearly trying to avoid visible pencil lines in this instance is not even a question.

By the way, if your problem is less about whether or not the pencil drawing is visible and more about how to actually do the drawing, this might be just what you are looking for.

I have a little Line Drawings Guide you can grab (if you haven’t already) that contains multiple line drawings done for you so that you can just get to the painting.

Line and Wash Technique

Another possibility is to use the line and wash technique. As the name suggests, this is the combination of a line drawing combined with watercolour washes. Notice that a line drawing suggests that it is mostly outlines and a few important detail lines that will likely be included rather than a fully rendered pencil drawing as in the previous case above (watercolour over pencil art).

Most often, the line is made with pen but a pencil makes sense too. Sometimes this is called ink and wash because an ink pen is used under the watercolour. 

I do love using this technique in my watercolour sketchbooks, particularly. I often start with a light pencil sketch which I then go over with a waterproof pen. I erase all the pencil leaving a clean line drawing and then add some lovely vibrant watercolour paint. Like this series of Blossoms and Bicycles for example.

You could just use strong pencil lines or even coloured pencil lines for this line and wash technique. So many choices… pretty terrific, don’t you think?

Watercolour painting with no visible pencil

Perhaps this is the kind of painting that my curious beginner had envisioned. A strong watercolour painting with no obvious pencil.

This might be my favourite I think. It is definitely possible to start out with pencil in the initial stage of your watercolour painting but to have no obvious signs of it by the time you are done.

So let’s talk about the different ways you can go about doing that.

How to avoid visible pencil marks in your watercolour painting

Direct Painting

If you want to be absolutely sure that you have no visible pencil marks in your finished watercolour painting you can avoid using the pencil at all.

Ah yes, no sketching…  just paint!

Indeed, this is not for the faint hearted. But it is also not quite as scary as you might imagine. 

(Fear not… there are other options, if this is not for you.)

Watercolour Pencil Sketch

If you want to draw with a disappearing pencil so to speak, then you might want to consider a watercolour pencil. If you want to give this a go, I suggest choosing a pale buff colour or something similar.

When the watercolour paint is added it will activate the watercolour pencil line and dissolve into the paint. This is why I suggest choosing a neutral colour that won't change the colour of the paint too much. 

The only downside to this approach is that once you have touched your lines with wet paint they are gone. Yes, that was the point, but it means that you only have your guidelines available to you for the first wash.

Coloured Pencil Sketch

You can use a coloured pencil to carry out an initial sketch and choose a colour that suits your subject so that it blends into the paint better. 

Again, it is best to use a very light hand so that the transparent watercolour paint has a greater chance of covering the coloured pencil lines.

Remember that coloured pencil does not usually erase so you will have to be quite careful if you choose this approach. 

However, you can find erasable colored pencils these days. These are my favourite things to draw with - I’ll tell you more about that in a moment. First let’s discuss the most commonly used approach - a light pencil sketch.

Light Pencil Sketch

The most commonly used approach is to use a light pencil sketch. You can begin with a graphite or erasable coloured pencil to place in a few guidelines for your sketch.

All these pencil marks are designed to do is to help you place the key elements in your composition. No details are required.

Take care to erase any extra marks you don’t need BEFORE you start painting. Once the pencil is trapped under a layer of dry watercolour paint it is effectively sealed in and you will not be able to erase it.

If your intention is to hide all these pencil marks in the finished painting then it is important that they are not too dark before you start painting. If you think you have been a little heavy handed - and even if you haven’t - it is a good idea to lighten the whole pencil sketch 

This is easy to do (and quite fun) with a kneaded eraser. Simply dab repeatedly at your sketch with the kneaded eraser. Each time you do, some of the pencil mark will transfer to the eraser and lift out. Keep going until you are satisfied that the lines are dark enough for you to see very faintly but do remember to stop before they disappear entirely.

You can see my whole process in this quick little painting video of a cute colourful frog. At about 00:28 in the video you see me dab at the whole frog to lighten the drawing.

By the way, if you would like a real time narrated video lesson for this frog PLUS 3 other fun painting subjects that are perfect for beginners click here!

My final tip for hiding your pencil marks is also really useful advice for your watercolour painting in general. It is really important to pay attention to the value structure in your painting.  The value structure is the patterns of darks and lights. If these are strong enough, the pencil lines are not necessary to distinguish the shapes from each other. The strong values also cover the pencil lines very easily. 

For example - if you are painting a white cottage and all the visible walls are the same value (white) then you will need the pencil lines to demarcate the corners of the buildings. Even with the pencil line your building will look flat. In reality, since each wall is receiving light at a different angle each wall has a slightly different tonal value. Painting the shadowed wall will hide the pencil line and indicate three dimensional nature of the building. 

What is the best pencil for sketching under watercolour paintings?

I think the best pencil is the one you are most comfortable with. Most of us are used to regular graphite pencils, and these are probably the most common choice. So let’s take a moment to consider graphite pencils for the initial sketch on our watercolour paper.

Graphite Pencils

An HB is the graphite pencil you are most likely to have - you know the kind we had at school which is in the middle of the scale from hardest to softest.

If you are aiming to have the pencil concealed by the watercolour then you will want it to be as light as possible. As a general rule, the harder the pencil the lighter the mark it will make. You might be tempted to reach for the hardest pencil you can find. 

However, take care with this - hard pencils can very easily leave very deep grooves in the paper. They actually damage the paper denting or even cutting in to the surface. When this happens, any watercolour paint applied will rush into the groove and form a strong dark line. 

That means that even if you erase the pencil mark, the groove in the paper is still there.  Once you add paint a harsh dark line will still appear as the pigment collects in the groove. 

If you are using a mechanical graphite pencil I find this increases the chances of these paper grooves. Once the lead wears down a bit you can easily end up pressing into the paper with the metal barrel of the mechanical pencil. Well, that’s what I find, but it’s also possible that I am just a bit too heavy handed.

So what about going for a softer pencil?

Seems wise… but, soft pencils are smudgy things. If you use a very soft pencil you have quite a good chance that your hand will end up inadvertently spreading the soft graphite across your page. Even if you avoid that there is a good chance that when you add watercolour paint it will lift some of that graphite (even if it is not technically a soluble graphite pencil). This will grey your paint a bit and your painting might get a bit of a dull pall instead of the vibrant watercolour you were hoping for.

Do I sound a bit negative about graphite pencils?

Ok, you got me - I am.

But that is just one of my own little idiosyncrasies. I have never managed to make friends with graphite, but it is one of the most popular drawing tools. Don’t let my prejudice stand in your way. Just choose an HB (I think you call this a number 2 in the US) and don’t press too hard.

So what are the alternatives to graphite?

Coloured Pencil

One of the things I really enjoy drawing with is coloured pencil. In fact I think it was when I started drawing with coloured pencils in my sketchbook that I realised how much I disliked graphite. 

For me the coloured pencil is soft and creamy, and that just feels really lovely as you sketch. It is also available in any colour you can imagine. 

You can choose something pale like a yellow, buff or mustard that will be easily covered. Of if you are painting a seascape perhaps you would choose some sort of blue or green or turquoise to better blend into your painting. 

My personal preference is to choose a coloured pencil which actually is erasable. These ones called Pilot Color Eno are my current favourite things to use for the underdrawing of a watercolour painting. They are mechanical which suits me because they don’t need sharpening but are still soft so I don’t find that they dent the watercolour paper.

There is another brand that I am aware of which I used before discovering the Pilot ones above. They are by Prismacolour and are called Colerase. Like traditional coloured pencils they have a wooden barrel so feel just like coloured pencil - but they do erase and come in a variety of colours.

What are the best erasers for pencil and watercolour

There are two main erasers that I like to have on hand - a normal white eraser and a kneaded or gum eraser. 

Kneaded Eraser

The  most important one for me is a kneaded eraser because that is very useful for lightening the sketch. You can also mould it into fine shapes in order to erase very small areas.

Kneaded erasers are described as self cleaning because you can just knead it a bit and the dirty outside edge you just used turns inside and you get a new cleaner edge to work with again.

Another advantage of this eraser is that it is very clean. Since it pulls up the colour and does not lift the surface of the paper there are no erasings to brush away. You know what I mean - those little curly bits of paper and eraser that are left behind when you use a typical school eraser. I’m calling them ‘erasings’. Feel free to educate me if they have a proper name!

Kneaded erasers are very gentle on the paper which is important for watercolour. For watercolour paper to perform at its best it should be treated with care. Brutal erasing can damage the surface of the paper which may mean that you will not get the watercolour effects that you are hoping for.

White Eraser

I also tend to keep a good white eraser on hand too. Sometimes - especially in my sketchbook where the paper is not quite as good quality, I prefer to use a tougher eraser. As long as it is clean it usually does a really good job of lifting pencil marks efficiently. It will also leave a bit of erasing which you will have to brush away.

Now if hiding the pencil in your watercolour painting is less of a problem than coming up with the line drawing in the first place, this might be just what you are looking for.

Are you on your own painting journey?

One of these might be useful…

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