watercolour mediums

Watercolour Mediums: A Comprehensive Guide

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By using watercolour mediums, there are some pretty awesome experiments you can carry out to create some unusual, intriguing and maybe even surprising results. If you think watercolour is a straightforward painting medium, learning about all the different liquids you can add to it to change its working properties may make you rethink that.

There are watercolour mediums that can aid you in achieving certain techniques, such as lifting colour from the paper to reveal the luminous surface below. Or you could choose a medium to do something simple, like increase the transparency, drying time, saturation or gloss of your watercolours. If you want to be really out there you could add texture to your watercolours. 

Sound fun? Read on to find out what all these little vials of liquids will do to your paint and how to take your watercolour paintings to a new level.

Table of Contents

Change the working properties of watercolour

Use the following mediums to change or enhance the typical working properties of your paint. Examples of attributes you can alter are the transparency, the drying time and saturation of the paint.

Gum Arabic

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Purpose: Increases transparency, slows drying time

Gum arabic is the binding agent used in the majority of brands of watercolour paints. When used as a medium, it can provide some benefits to increase the workability of your colours.

It increases the transparency of the paint, reduces the staining properties of watercolours and increases the open working time, making the paint dry slower. 

The medium makes it much easier to control the spread and flow of watercolour and the pigments prone to staining won’t seep into the paper as much. This makes it easier to carry out the lifting technique.

Ox Gall

Buy natural ox gall here

Purpose: Improve adhesion, separate layers, increase wetting properties, controls flow

Ox Gall is obtained from a bovine gall bladder and thinned with alcohol, however you can get a synthetic alternative that has the same properties and behaves in the same way, if you don’t use animal products.

The medium has several uses. Use it as a surface degreaser—apply it to a layer of paint to achieve better adhesion and to separate the paint layers. Ox gall can also be mixed in with the paint to increase wetting properties, flow and to be used as a self levelling agent.

The medium controls the spread of the paint. As certain pigments will disperse further and more rapidly across the paper in water, ox gall can be added to water to reduce this spread and control the flow.

Golden: QoR medium (synthetic ox gall)

Buy it here

Purpose: increases flow, increases transparency, glossy finish, increases saturation

Golden uses a special formula as their binding medium in their watercolour paints. They also sell this formula separately to be used as an additional all purpose medium to enhance the properties of watercolour paint. It can be added to any brand of watercolour but it of course goes hand in hand with their own brand of paint.

The medium should be used in small amounts to improve the flow and transparency of watercolours. If you use it in larger amounts it will increase the gloss and saturation of your colours.

Honey

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Purpose: increases brightness, elasticity and shine

Natural, raw, single flower honey can change the properties of your watercolours in a multitude of brilliant ways. Single flower honey is much clearer than other types of honey, meaning that the natural colour of the honey will not alter the tones of your paint. 

Add a tiny, pea sized amount to watercolour to increase the shine, transparency, brightness and adhesion of the paint layer. It also gives the painter greater control over the paint flow.

Change the finish of watercolours

Gloss medium

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Purpose: slows drying, adds shine, remains resoluble

This medium can be painted neat over dried watercolour, to be used as a varnish, or it can be combined with colour to give the surface a reflective, glossy quality. Colours will remain resoluble when the watercolour medium is added. The gloss medium slows drying time, however its effects are diminished with the addition of water. Don’t mix this medium straight in the pan.

Iridescent medium

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Purpose: Adds a shimmering effect to watercolour

Apply this medium over a dry wash, or add to a transparent pigment to create a luminescent shimmering effect. This medium will make your colours sparkle on the paper and it will increase the lightness of the colour. In order to retain the colour’s natural shade (to retain its relative darkness) apply the watercolour medium as a separate layer over dried watercolour. 

When used with opaque pigments, the iridescence will not be as visible.

Shine medium

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Purpose: retains resolubility, makes colours sparkle

You can mix with watercolour paints, or use neat on your surface for a pearlescent effect, an iridescent and lustrous rainbow of colours, or a milky opalescent shimmer. The medium slows the drying of watercolours and retains resolubility. Mix the medium onto a palette with a colour, not straight onto a pan.

Watercolour mediums to alter solubility

Fixative medium

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Purpose: Makes paint waterproof when dry

Normally, watercolour paint is resoluble. This is great for when you want to keep working from the same blob of paint you poured onto your palette for weeks on end, but not so great if you want to prevent colours from intermixing on your surface. 

You can get some interesting effects by using this medium to create glazes, that is layers of transparent paint that sit separately from one another on the surface, subtly altering the hue of the previous layer. As this fixative medium also increases transparency, you can play with this effect, which will yield bright and luminous results.

One thing to take care of is pouring this medium out onto your palette. As it dries, it can’t be rewetted to clean. So I would advise to pour a tiny amount onto a disposable sheet palette (you could also use plastic wrap), that way when it dries you won’t have to worry about scrubbing or trying to peel it off your palette. Clean the brush you use to apply the paint with the medium thoroughly after you use it—you can get brush soap that will make the job that bit easier too.

Fixative varnish spray

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Purpose: final protective coat 

By spraying your watercolour with a fixative, it provides a final protective coat for your work. It acts almost like a varnish to secure the paint, making it insoluble and protected from dirt, water droplets, humidity and all types of normal wear and tear that could ruin the painting over time.

Make sure to shake the spray well before use and apply in a well ventilated room by spraying at around a 30cm distance in an even, thin coat over the entire painting. The fixative is age-resistant and fast drying

If you are using a synthetic surface to paint onto like Yupo, it’s essential to apply a fixative once the painting is dry. 

Create texture using watercolour mediums

If you thought that creating textured work was reserved for the acrylic and oil painters, you might be pleasantly surprised.

You can create incredible textured paintings using watercolour too. The application process is a little different, but there are a few different mediums available that give you this option. I’ll walk you through what they are and tell you how to use them.

Modelling paste

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Purpose: Creates a textured, 3D ground to work on

This can be used as a ground, upon which you can paint with watercolours. It can be applied to a surface with a palette knife or stiff brush to create three dimensional structural effects. The paste will stay as you place it on your surface. You can also use tube watercolour to tint the modelling paste. 

Granulation medium

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Purpose: gives watercolours granular texture

Only a few watercolour pigments will naturally granulate, most provide an even paint flow. Granulation can be used to a watercolourist’s advantage, to create the illusion of detail across ground, in stormy skies or on animal fur. 

Spray the atomiser over wet watercolour, to give non-granulating watercolours a textured appearance. It also intensifies the effects of granulating watercolours, giving an almost speckled appearance.

Impasto watercolour medium

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Purpose: mix into paint to increase viscosity

Impasto is a technique traditionally associated with oil painting. The technique involves applying paint to the surface in thick strokes where the appearance of brushstrokes is retained on a surface. Because watercolour paint has such a low viscosity, you need to add a medium to achieve this effect.

An impasto medium will reduce the flow of paint, make it thicker, give it body and volume. The textural effects are much less pronounced than with acrylic or oil impasto techniques and brushstrokes will not necessarily be fully retained on the surface. It gives paint a light texture.

The liquid comes out of the tube in a gel and it can also be used with gouache paint. Because the paint becomes so much thicker with this medium, you may need to get a slightly stiffer brush to control it, look at synthetic brushes such as the Escoda Primera Teijin Brush.

Create white space in your watercolour paintings

Having brighter areas of your painting is essential. It’s how you show a light source, areas that are reflective and small highlights.

In watercolour painting, this is achieved by allowing the light surface to show beneath a fine transparent layer of paint. Mediums can be used to lift pigment from the paper, to reveal lighter areas, or mask specific areas to prevent the colour from adhering to the surface.

Lifting medium

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Purpose: lifts colour from paper to reveal layers beneath

Watercolour pigments vary in their staining properties. In other words, the colour of some pigments will be absorbed into the paper, while other pigments will sit on top of the paper’s surface as a separate layer.

Many pigments will be absorbed into the paper somewhat but also sit in a separate paint film, these are semi staining. The way you can tell if a colour will stain or not, is by looking at the paint tube or pan label. A filled in triangle means the colour will stain, a half filled in triangle means that it is semi staining, if the triangle is not filled in, it won’t stain the paper.

The problem with staining colours is that it’s very difficult to carry out the lifting technique—whereby pigment is lifted to reveal the bright white surface below. This technique serves to create essential whitespace in the painting for areas of light and highlights.

With a lifting medium, you can remove areas of dried watercolour paint by cleanly lifting colour off with extra water. Apply the lifting medium to the paper before painting and leave it to dry. If you are using a soft watercolour paper, paint the medium on the area you anticipate you will want to remove colour neat, if you have a surface that is thicker, or primed, you can thin the medium with some water before applying. Once the watercolour paint layer has dried over the lifting medium, get a clean wet brush and start brushing away the paint. It will remove colour from even the most staining pigment.

Clean your materials, such as your brush thoroughly after use with this medium.

Wax Resist

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Purpose: masking areas of a surface to retain background colour

Use this beeswax medium to mask areas on the surface. Apply it to your surface before you add the paint layer. When you come to paint, the wax layer will repel the water and pigment, covering the areas that you applied it to. 

The medium makes an excellent aid for creating precise areas of colour separation in your painting. The waxed area will retain its original colour when removed, so you can apply it over areas that already have paint on them.  

Masking fluid

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Purpose: masks areas of surface

This works in a similar way to the wax resist. It can be applied over a white paper surface, or on top of dried watercolour to prevent adhesion of watercolour layers painted on top. Use it to create light areas, areas of white space, fine details with colours that don’t bleed into one another, or hard edges.

Apply it with a paintbrush, or with something sharper like the end of the paintbrush handle for detail work. 

Masking fluids are usually made of latex and they peel off the paper once dry. Peel with your finger, a rubber or tweezers.

Watercolour mediums: Pin it!

Watercolour painting: Further reading

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