A brief guide to acrylic mediums & additives

Since their initial inception in the 1950's acrylic paints have become the staple medium of artists all over the world due to their highly versatile nature. Being water-based, unlike oils, makes them generally easier to clean up and safer to use due to the lack of solvents that oils require for diluting and cleaning. Acrylics also have access to a wide variety of additives and mediums, which can be mixed with paints to affect its properties in a variety of ways.

By the end of this article, you should have a good grasp of the most common mediums and additives you might find useful additions to your toolbox, and how they might benefit your future painting endeavours.

Matt & Gloss Medium

A selection of acrylic Gloss Mediums, adding some is great way to increase the intensity of acrylic colours.

Sometimes referred to as "acrylic painting medium" consists of the acrylic binder used in paints without any pigment in it. When mixed with acrylic paint they extend the paint, increase the transparency and maintain no colour shift from wet to dry. Think of it as mixing transparent paint into another colour, you get more binder but not more pigment.

If you are using colours that dry with different finishes (such as GOLDEN Heavy Body Acrylic) you can mix some medium into those paints to give all the colours you are using a uniform finish once dry.

• Winsor & Newton Galeria Acrylic Mediums - An economical acrylic medium for increasing transparency and extending colour.
• Winsor & Newton Professional Acrylic Mediums - Artist quality acrylic medium for increasing transparency, flow and extending acrylic paint.
• Liquitex Professional Acrylic Mediums - High quality artist's acrylic medium for extending colour and increasing transparency. Available in Matt and Gloss
• GOLDEN Fluid Matte Medium - Artist quality fluid medium that dulls sheen, increases flow and transparency. Can be used to seal wooden panels and as an adhesive for decoupage projects. 

Acrylic Varnish

Liquid acrylic varnish comes in a variety of sizes and brands. A soft flat brush is also key for a smooth application.

The best way to ensure your paintings are safe, and keep them looking their best for the longest time possible, is to seal them with a varnish. Varnish protects all the previous layers of paint it is applied to with a durable protective top layer. Some varnish is removable, check the product description if you plan on using a varnish you might want to remove in the future. Acrylic varnish comes ready to use in a pot for brushes or as spray varnish in a can. 

For a comprehensive guide to varnishing take a look at our blog all about varnishing here:Varnishing Acrylic Paintings

• Winsor & Newton Galeria Varnish - Dries in a clear protective resinous film and offers protection from light, dust and surface damage. Apply with a brush in multiple thin coats.
• Montana Varnish Spray - A clear protective varnish with built in UV resistance to reduce fading. Increases durability, protects against the weather and will not yellow with age.
• GOLDEN Polymer Varnish w/UVLS - Robust acrylic polymer varnish with UltraViolet Light Stabiliser (UVLS) designed to give maximum protection against prolonged exposure to UV light sources.
• Liquitex Soluvar Acrylic Varnish - A solvent based varnish which dries to a permanent clean finish but can be removed with high strength genuine mineral spirit or turpentine.

Glaze Medium

Glaze mediums can be an excellent way to create smooth, creamy blends with acrylic paints. 

The glazing technique involves applying a very transparent layer of colour over a previously painted area to create a subtle colour difference. A glaze can be used to tint a specific colour with a single pass or be built up over several applications to make smooth colour transitions. The issue that you might run into when trying to glaze is getting the correct consistency. Thinning acrylic paint solely with water leads to the paint becoming under-bound, where the pigment separates from the binder. This causes problems such as a chalky or gritty finish and weak paint adhesion. Glaze medium increases the transparency of acrylic paint and lowers the viscosity without breaking down, reducing the integrity of the binder.

Glazing mediums slightly increase paint drying time, have self-levelling qualities, increase flow and dry with a smooth finish.

• Liquitex Profession Glazing Medium - Glossy medium that dries with a clear finish when used neat. Use with acrylic paint to create glazes or acrylic ink to make smooth acrylic washes.
• GOLDEN Gloss/Satin Glazing Liquid - Highly fluid acrylic glazing medium which can be used to thin acrylic colour without diluting pigment strength. Use to create highly transparent glazes when mixed with acrylic colour and comes in Gloss and Satin finishes.
• Winsor & Newton Professional Glazing Medium - Acrylic medium which increases flow, maximises transparency whilst maintaining colour strength when used with Winsor & Newton Artist Acrylics. Dries with a glossy lustre.

Flow Improver

Flow Improvers must be diluted with water, when used this way the thin acrylic colour and increase flow without separating the binder from the pigment.

Flow improver is an additive that decreases the surface tension of acrylic paint and increases its flow. Some brands have their own name for flow improver such as; flow aid and wetting agent, but they are all inherently the same thing.

Flow improvers are a concentrated surfactant, a substance that reduces the surface tension of liquid. They should only be used sparingly and mixed with clean water and not added directly to colours in large amounts. Check the bottle for instructions regarding dilution ratios and usage.

• Winsor & Newton Professional Acrylic Flow Improver - A clear surfactant that reduces paint surface tension. When diluted with water and used with acrylic colour it increases smoothness and can assist with glaze techniques.
• GOLDEN Wetting Aid - Surfactant solution that decreases the surface tension acrylic paint and increases flow whilst greatly reducing paint mark retention. Ideal for when smooth application and thin paint layers are required.

Retarder / Slow Drying Medium

Slow drying mediums are usually viscous gels with either a clear or cloudy look. They dry completely clear so it will not effect the colour once it has dried.

Retarder or slow drying medium is a gel additive that increases the drying time of acrylic paints by decreasing evaporation speed of the water in the acrylic paint. This allows for acrylic paint to be worked and blended for longer before drying and facilitates the alla prima (wet-on-wet) technique, which is usually reserved for oil paints and their naturally slower drying time. It also keeps paint usable on the palette for longer.

It is important not to mix too much retarder into your paint as it can lead to excessive tackiness, overly long drying time or the paint cracking as it dries. Always check the instructions for mix ratios.

• GOLDEN Retarder - Slows water evaporation from acrylic paints and increases open time up to 40%. Mix with paint on palette to prevent skinning and keep colours workable for longer over extended painting sessions.
• Winsor & Newton Professional Acrylic Slow Drying Medium - Clear acrylic medium which increases the drying time of colour by up to 4 times when used with Winsor's own artist acrylic paints. Dries with a slight sheen.
• Liquitex Professional Slow-Dri Blending Gel - An acrylic gel medium that slows drying time, boosts workability for up to 40% longer. The medium softens edges and increases blending potential for acrylic paint.

Pastes and Gel Mediums

This iridescent medium provides a pearl-like shimmer where it has been applied, when mixed with colour it creates a pearlescent paint with a shimmering finish.

Acrylic paint is an incredibly adaptable medium and benefits greatly from a broad selection of pastes and gels that can be used to increase viscosity, create shimmering effects and so on. Here are selection of some of those mediums: 

• Daler Rowney Texture Paste – A thick paste that adds a fine grit texture as well as additional body to paint allowing for impasto style work with a toothed feel.
• GOLDEN Crackle Paste – An opaque white paste which cracks with dramatic fashion as it dries. Provides an aged and weathered look, the cracks increase with paste layer thickness and take well to glazes and wash techniques.
• Galeria Heavy Structure Gel – Translucent with a satin finish, this thick gel greatly increases paint viscosity. Adding high peak retention is great for creating highly textured layers of paint similar to impasto oil painting techniques.
• GOLDEN Clear Tar Gel – A highly viscous gel with a highly distinct stringy quality akin to syrup. This makes clear tar gel excellent for pouring and drizzling techniques to create thick weblike patterns and Jackson Pollock style paint dribbles.
• Liquitex Professional Glass Bead Texture Gel – A thick, transparent, gloss gel with glass micro-beads that provide a satin shimmering look when dry. Can be mixed with colour for a dramatic shimmering bubble effect.
• Galeria Iridescent Medium – A translucent acrylic gel with an iridescent pigment for creating a shimmering prismatic interference effect with paint. It can be applied directly to work or mixed with acrylic paints to make iridescent colours.
• GOLDEN Clear Self Levelling Gel – A fluid acrylic medium which increases flow and imparts a smooth level finish to the paint it is mixed with.
• Liquitex Professional Pouring Medium - This medium increases flow and maintains colour strength for pouring techniques, creates marbling effects and colours do not bleed into each other when pouring. Dries with a high gloss finish.

Acrylic Gesso

This canvas has been primed with white, clear and grey gesso and then left unprimed on the far right side. You can see how the paint has bled into the unprimed space and gives a fuzzy edged finish.

This preparation is a combination of base layer and surface sealer, acting to provide a suitable surface with good adhesion for paint. The most common variety of gesso is white but it can come in other colours such as black, grey and even a transparent clear gesso, which provides a suitable starting surface but lets the supports original colour come through.

For a more comprehensive guide to gesso you can check out this article all about gesso here:What is Gesso, Size and Ground?

• Daler Rowney Simply Gesso - an economically priced student quality gesso primer fit for use on paper, canvas and wooden board.
• Galeria White Gesso Primer - high quality acrylic primer providing a suitable base layer for painting on top of that acts to seal the support and provide adhesion for paint.
• Winsor & Newton Professional Acrylic Gesso - a range of superior artist quality gesso that provides excellent absorbency, adhesion, coverage and tooth in fewer coats.
• Liquitex Professional Clear Gesso - premium quality gesso that provides good adhesion and absorbency for acrylic paints whilst drying clear and thus preserving the surface's original colour.
• Daler Rowney Black Gesso Primer - provides all of the same qualities as standard white gesso but is better suited to paintings that require a dark base layer, skipping the need to repaint white primer black. Can be mixed with White Primer to produce varying shades of grey.