One of the best things about creating is that most of it depends on the creator. There aren’t always hard and fast rules that everyone has to adhere to, especially in the world of painting. However, there are some techniques that can be used to make painting easier, and techniques that make paintings look or feel a certain way. Sketching before a watercolor painting is one of those techniques. 

Should you sketch or outline before watercolor painting?

Sketching before watercolor can be helpful for paintings with structured lines, such as portraits or architecture paintings, but sketching is not required for watercolor paintings. Usually, pencil lines are used as a guide to make sure the composition and proportions are correct. Watercolor without sketched lines often look more soft and spontaneous, which some artists prefer. 

Either method is fine; there are many artists that choose to lay down a rough sketch before breaking out their watercolors. Beginners may find it especially helpful to have a pencil outline of where the major items or the details should go before they start painting, but many professional artists choose to sketch before painting as well. Sometimes it just helps to have pencil marks as a placeholder to keep the composition correct or to keep the details in place. 

watercolor painting of two yellow fish
Watercolor with sketched lines in pen

What type of pencil should you use with watercolor?

Options for pencils to use under watercolor paintings include: colored pencils, watercolor pencils, or any graphite pencil with hard lead, like a 2H pencil or a mechanical pencil. The main thing to note is that the pencil lines need to be very light, otherwise they will show through the finished painting.

Many artists like using graphite pencils, either because that’s how they’ve always done it, or because they like the look of the light gray lines keeping the colors in place. Some choose to use a very light touch with a mechanical pencil (with 0.3 or 0.5mm lead), while others choose to use a very hard artists’ pencil, with a 2H lead or higher. 

open journal with watercolor painting of a mushroom

Others use colored pencils to achieve different effects in their finished paintings. Yellow colored pencils can be used because they leave no trace once paint is layered on top. Cyan or light brown colored pencils can be used to give an antique feel to the painting. The most common way for colored pencils to be used with watercolor paintings is to use the same colored pencil to make the sketch as the final paint color that will be used on top of it. This also makes the colored pencil line disappear once you paint over it with the same color, and it can enhance the color of the final image instead of leaving a gray pencil line. 

Many people prefer to use pens to sketch with their watercolor paintings. This gives a distinct feel to a painting, and it’s used very often in art forms such as urban sketching, where a quick sketch in pen is done to depict someone’s surroundings, and then color is added afterward. Pen and watercolor go really well together, just keep in mind that you’ll need to use a pen that’s alcohol-based, not water-based. A water based pen (like a crayola marker or some gel pens) will break down and dissolve when paint is added on top. Alcohol based pens and markers will not run when water is added, so these are ideal for ink and watercolor drawings. I’ve got a whole post here that can help if you want to see some examples of pens in each category.

Watercolor pencils can also be used in a similar way to using colored pencils. They come in many colors and are water soluble, so once the paint hits them, the line itself will dissolve into the painting. However, they are more expensive than the other options, so it may come down to what’s affordable and what’s easily available. 


Can you erase the pencil marks after painting?

Pencil marks from a sketch can’t be erased once paint is laid down on top. This makes it important to plan ahead a little bit. Some people just use very light lines that won’t be noticed once they are painted over. Others either make the lines accentuate the painting, or they use a pencil that allows the sketch to blend in to the final painting. They either use a pencil with water soluble lead that disappears once it gets wet, or they choose colored pencils that blend in to the color of paint they are using in that section of the painting.  

Can you sketch on watercolor paper?

You can absolutely sketch on watercolor paper, many artists choose to lay down a rough sketch before they start painting to keep their composition. Just be careful not to press too hard with the pencil while sketching, or it will leave track lines on the paper that can affect the final painting. 

Reasons not to sketch before watercolor painting

There are some artists who just prefer the look of a free-flowing watercolor painting, with no border lines to worry about. Other artists don’t like the look of the gray graphite pencil marks combined with the finished painting.  

Additionally, the graphite from the pencil that is left behind when you sketch can make the watercolor that is painted on top of it a murky gray color. This effect will be more noticeable with softer pencils. If you use a pencil with soft lead, like a 3B or 5B pencil, it will leave behind a lot of crumbly graphite. When you paint over this with fresh watercolor paint, some of that graphite can be picked up by the paint and water mixture and carried around your painting. 

Ultimately, it may take practice for you to decide which scenarios you will need to use sketching before watercolor painting. Remember that art is subjective, and there are no wrong answers here. Sketching can help you achieve the look you want in your final painting, but if you prefer the look of paintings without sketched lines, then don’t use them if you don’t want to. Just go create something you’re proud of!