Picking the right medium for your artwork is really important however don’t be afraid to experiment with different types as you will be surprised how easy they are to use.
First up we need to look at exactly what are mediums. Initially it can be broken down to types of painting medium like oil, water-colour or acrylic painting, but the type of mediums I want to discuss today are the additives like gels, pastes, varnishes etc. I prefer to use acrylic paints these days so its best if I stick to mediums to use within that field for this post.
There are many types of additives available and each brand types with the same name will vary to some degree also. I personally prefer to use the Golden range of mediums as they suit the type of work I do and there are so many choices in their range alone that it makes it diverse and interesting.
Starting from the basics-
Gesso Primer which we use to seal painting surfaces such as unprimed canvas, for both acrylic and oil painting. Gesso produces either a matt white or black surface with a slight texture or tooth which makes it easier to paint on. It’s a good idea to do at least several coats of Gesso and to lightly sand between the layers as they dry; especially if you want a really smooth painting surface.
Flow Enhancers these are colourless liquids added to the paint to reduce viscosity and enhance their flow. I find they are great for working on large areas of work where blending and a smooth finish is required. The drying time is extended when you use a flow medium so you can work on a piece for longer than usual. Unlike water they do not break down the pigment of the paint. You can also use a retarder for this but it works slightly differently
Retarder is for when you want to prevent your acrylic paint from drying too fast when painting. If you're trying to blend colours on the canvas or you're just not that fast a painter then retarder might be a good investment for you. Retarder slows the drying speed by up to 50%. Mix it in with the paint before applying it to the artwork. It will increase the paints transparency if too much is mixed in so its not a good idea to use it to excess in a mix along with the fact that the paint might not dry at all!
Glaze Medium these come in a gloss or matt finish. I prefer to use them over a retarder. They increase the transparency of colours for glazing work. I like to use a lot of glazing in my work, this is where a translucent colour is painted over another dried colour to let that underlying colour glow through like on fruit or for skin tones. It does take longer to dry than just paint but its worth the effort.
Impasto Gel Medium
Gels are a great additive to bulk out paint particularly if you use an impasto effect in your work where the paint is applied thickly; or to help make concentrated paints go further. You can use a brush or palette knife and the marks they create will be retained in the finished effect. The only down side is the drying time as it can take quite a bit longer. Gels are available in matt or gloss which give different effects and often can be opaque which will change the colour, lightening them slightly due to the white pigment in them. A clear or gloss gel won’t dilute the paint pigment or affect its translucency. Think of a gel as colourless paint, as they are composed of 100% acrylic polymers similar to acrylic paint. I find they work well as adhesives when adding mixed media to an artwork like shells or material in fact much better than any glue can. The Golden range has several types of gel from soft through to heavy duty; you choose the density by how much texture and form you wish to have. Other ranges often only have one type but they all have their good and bad points.
is a thick, white opaque paste which is used before applying paint. For this reason, one of the most used acrylic mediums, this makes it much more economical than using thick dollops of paint; however you can mix in the paint first if you are factoring in the change of colour it will create. Depending on the thickness used, be aware that it can also crack. However, if you use it in conjunction with a gel, the cracks can be filled in. A combination mix of these two acrylic mediums, painted over, will work well on flexible surfaces like stretched canvas. Golden have a light moulding paste that is simply heaven to use, it’s an absorbent ground that is great to use with washes of colour and can be built up a lot without any weight issues along with great flexibility so it works well on a canvas support on its own.
It’s important to note too that most gels and paste mediums will shrink by 30% when dry so you need to compensate for that when applying your product.
Acrylic Matt & Gloss Varnishes
I would have to say that the ‘varnish’ questions come up many times from other artists, the how to, why to and what to use ones being the most common. So here is the low down on varnish. There are two main reasons why you should varnish your work. They will even out the matt and shiny areas on your artwork that were created by different products and methods you used while creating them and most importantly will protect your finished and dry paintings from dust and most environmental pollution. I prefer to use a brush on varnish however when I have a mixed media piece that is delicate a spray varnish works better.
Varnishing doesn’t always mean shiny either, there is gloss, satin and matt finishes. Satin obviously being between matt and shiny is just that, neither shiny nor matt and is my preferred finish with my artwork in that it doesn’t look flat nor does it detract by being too shiny.
Do be aware though that some acrylic 'varnishes' are spirit-based and will need to be cleaned off with low odour thinners or turpentine if the occasion calls for it like a restoration in years to come. You will also need to clean your brushes differently after using them as they won’t clean out in water. Most acrylic 'varnishes' however are water-based and are made from an acrylic polymer, which is similar to what acrylic paints are made of. Once dry, these varnishes cannot be removed.
I often teach a night school class for students who may wish to learn more about the use of paint mediums. Please feel free to enquire if you are interested in when my next classes are or ask around your local art community for any classes near you.
Posted: Saturday 16 January 2010