Why You Should Do an Underpainting for Acrylics

Have you ever tried to do a dark painting on a stark white canvas and have become frustrated when the white shows through? Or are your shadows and highlights not quite right and your painting looks a little flat. An underpainting for your acrylic piece may be just what you need to prevent this frustration.

An underpainting is generally thought of as an old masters technique but it is an important step in the process of creating a painting. It can be used to create shadows and depth, as well as provide texture, color and contrast for your work and give you a guide for tonal values. 

The underpainting also helps you plan out where colors will go on top of it, which helps make your painting more cohesive.

I usually start a painting by doing an underpainting, which is a great way to get the values in place before adding paint. To understand more about values, read my post on Value.

Since a lot of paint colors tend to be transparent or semi transparent, doing an underpainting can save you from doing multiple layers of paint to get good coverage of the canvas.

An underpainting will help your final project have more depth and dimension and is worth the little extra time it takes.

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Do You Need an Underpainting?

The short answer is no. No painting “”needs” an underpainting. The real question is….. Should you do an underpainting? To that I would say yes!

An underpainting not only covers a stark white canvas but it also adds depth and dimension to your painting. It gives you a base for your detail colors and helps you map out lights and darks before you glaze over them with paint.

Not everyone likes the effect of an underpainting. If it’s not what you want or you don’t have time, feel free to skip right to the painting. There are no rules.

If you are an oil painter, you can do your underpainting in acrylics since it dries faster than oil. You can’t however put acrylics over oils. Since acrylic paints are water based they would just sit on top of the oil paint and slide right off.

What is the Best Color for an Underpainting?

I usually start a painting using various shades of greys or browns as an underpainting. Sometimes I will use blues or purples if the finished painting will be very light. That’s just my preference.

The best rule of thumb is to use whatever is the dominant color in your painting. So if you were doing a sunset on a beach, you could go with a warm yellow or an orange tone depending on which colors you want to peep through here and there.

You could also use a contrasting color for your underpainting. Many landscape artists use some type of red as an underpainting. Usually an earthy red like burnt sienna. 

The red tone contrasts with the greens in the foliage and creates interest and vibrancy and increases the saturation in the finished painting.

Some artists stick to one earthy tone, such as a brown or yellow ochre,  for all of their underpaintings, no matter what the subject. They feel more comfortable with this method and have learned to use it to their advantage over time. 

It’s really fun to play around with the colors of your underpainting to see what effects you can get. Use old canvases, canvas paper, watercolor paper or even cardboard to experiment and see what colors speak to you.

Don’t forget to make notes about the colors you combine for future use. If you do your swatches on paper they are easier to keep for a visual record.

I am thinking about using my swatches as wallpaper in my studio since I have so many. 🥴 

Color Temperature in an Underpainting

Be aware of color temperature in your underpainting. The use of warm or cool colors can set the tone for your painting.

Cool colors like dark blues, will give your painting a cool tone. Think of a night scene in winter.

Warm colors, such as browns, will give your painting a warm feel. Think of an autumn scene with falling leaves.

For more information on color temperature see my post on Warm and Cool Colors.

The only colors I don’t recommend for an underpainting (unless you are doing an abstract painting) are bright, saturated colors like vibrant greens or bright oranges. Stick with more muted tones so your underpainting enhances your painting and doesn’t compete with it.

How to Create an Effective Underpainting with Acrylics

There are a number of techniques and tricks that can help you create an effective underpainting. How you do your underpainting depends on what you want to achieve.

Full coverage of the white canvas: If you just want to cover the white of the canvas before continuing with your painting, a color wash would be your best bet.

A wash is simply a layer of diluted paint. So for acrylics, you can dilute your chosen color with water or acrylic medium such as a glazing medium or a fluid matte medium.

The amount of water you need to add depends on the effect you want. A general guideline is between 30% to 60% water.

Less water will give you a more opaque coverage and more water will give you a more watercolor effect.

For mediums, the ratio is about the same, however you should read the manufacturer’s instructions on the bottle since each type of medium and each manufacturer has a different formula.

The difference between using water and mediums is that water will help the paint actually sink into the canvas, whereas a medium causes the paint to stick on top of the surface and may add a slight sheen. 

Mapping out lights and darks: You can use an underpainting to add the tonal values to your painting before adding the actual colors.

Start by painting in the darkest values using whatever color you have chosen for your underpainting. These dark areas will deepen the paint that goes over it and create shadows or darker hues. 

Start to put in some shapes and lines, but don’t worry about them being perfect yet 

You can then continue to add midtones and lighter tones using thinner layers of the paint or, if this is not light enough, you can mix it with a little white.

You can use more than one color in your underpainting. For example, if you are doing a portrait of a person against a bright background, you can use a muted earthy color for the underpainting of the subject and a brighter color for the background.

Use whatever you think will work best for your painting as long as you get your values correct.

Greyscale or grisaille underpainting: This is an underpainting done entirely in various shades of grey. Darker greys for the shadows and lighter greys for the midtones and lighter areas.

This is one of my favourite ways to paint. I use the brush to draw out my painting on the canvas. The grey paint acts like a pencil to do the drawing. If I am not happy with the composition I can simply paint over it.

Once the underpainting is dry, you can use thin washes of paint to tint the colors over the grey, building up layers until you are satisfied with your work.

You can also use thicker applications of paint to completely cover the grey, using the underpainting as a guide to placement of values.

 Terminology

If you have done any research yourself about underpainting you may have come across different terms used for this type of painting. It can be a little confusing so I have listed below different terms and their definitions. They all mean basically the same…covering the white of the canvas.

• Underpainting: an initial layer of paint to cover a canvas and then overlaid with other layers of paint.
• Wash: a semi-transparent layer of diluted paint
• Grisaille: a painting done in black and white or shades of grey
• Verdaccio: a painting done in shades of green
• Brunaille: a painting done in shades of brown
• Ébauche: initial sketch done in muted tones of the final colors
• Imprimatura: an Italian word for the first layer of paint

As I said, an underpainting is not strictly necessary and many artists don’t use this technique but it is certainly worth the extra effort and may actually make the painting easier. I encourage you to give it a try and see if it is something you would like to incorporate into your work.

If you have questions you can leave them in the comments below. You can also join our free Facebook group, Trembeling Art Creative Corner, where you can ask questions, post your work and get to know some fantastic artists from all genres and skill levels. 😊

Thanks for reading.