Glazing Mediums: My Conclusions So Far

David Cranswick's Glazing Medium
(aka Liquid Glass)

This is my most tried and trusted medium to date, and the one used for most of my paintings in the last few years. I have watched David Cranswick preparing it and found it all rather alchemical... (it involves cooking up damar crystals with cold-pressed linseed oil, to a very specific temperature, proportion and for a specific length of time, before passing the resulting goo through 2 layers of muslin). As can be seen in the photo below, the finished medium is a light golden colour and has a semi-transparent gel-like consistency. At the time of use, approx one part poppy oil is added to two parts of the medium, and (if desired) a couple of drops of dryer, such as cobalt siccative can be added to speed drying.

In use, the medium is applied to the surface of the canvas or panel and then rubbed back by hand until it is barely there. Used in this way, it offers a smooth surface to paint into for the best part of a day without starting to drag, assuming too much siccative has not been added. It is generally dry enough to start on the next layer the following morning. One benefit of this medium is that it gives a nice level of translucency and gloss to each layer, without being overly shiny. It does not thin the paint causing brush strokes to disappear, so it is possible to be a little 'painterly' with it. Also, you do not need to varnish the finished painting, as the damar content achieves a varnish-like finish (it is affectionately known in David's studio as 'Liquid Glass'.) I would advise anybody wanting to know more to contact David Cranswick directly (http://www.davidcranswick.com/) or wait for his book to come out!

Lefranc and Bourgeois 'Flemish' Mediums

Last christmas I received two new glazing mediums by Lefranc and Bourgeois... tantalisingly
entitled 'Flemish medium' and 'Flemish Siccative Medium' (I know it is pathetic, but dreams of van Eyck are unavoidably triggered.) So far I have tried out these mediums on the 'Still Life with Apples', above, and here are my early conclusions.

'Flemish siccative medium' - this comes in a bottle and is made up of copal gum, linseed oil and rectified turpentine. The colour is a rich amber, and the medium flows rather nicely out of the bottle. Generally, it was easy to use and does dries within a few hours. On first use, I applied it to the surface of an underpainting and also mixed a tiny amount in with my paint. The trouble came when it appeared to lift my underpainting in places, but I confess that my underpainting may not have been 100% bone dry at the time. I will certainly try this medium again.

'Flemish Medium' - this comes in a tubs and is made up of Gum mastic, linseed oil, essence of spike and cobalt-zirconium siccative. The colour is a mid-amber and the consistency is a very thick gel, verging on gluey. It came out of the tube reluctantly and then needed a fair amount of squishing with a palette knife before becoming malleable enough to paint with.

The Woes...

More than the 'siccative' medium, I found the Flemish Medium very difficult to get to grips with. At first I was just not sure what to do with it... it was so thick and sticky that it could not sensibly be mixed with paint. So I thought I would stick to my usual method of applying a thin layer to canvas and painting into it with neat paint. Well that was easier said that done... getting this stuff applied thinly to anything, by hand or brush, is a challenge.

Eventually I resorted to the palette knife in order to spread a thin layer of the medium, like marmalade, over the surface of the canvas. Then I used a stiff 'brights' brush to scrub it into the surface as thinly and evenly as possible, rubbing with the heel of my hand where necessary. This done, I then had exactly the same trouble with the paint... it was a lot like painting into superglue! Again, I reverted to a flat 'brights' brush to scumble paint into the surface.

The Pros...

Now the interesting thing is that although none of this sounds like much fun... the resulting paintwork actually looked rather good. So I persevered with several layers in this way, and gradually found ways to apply paint more softly, even with a sable brush, over the gluey surface. So... to summarise. Despite the problems I had getting to grips with this medium, there are several benefits to it.

• Firstly, the finished painting has a high gloss finish, that seems very resilient and won;t need varnishing.
• Secondly, the colours appear bright and pure.
• Thirdly, the paint layers all dried very fast - within 2 - 3 hours, so more than one layer can be achieved in a day.

I will certainly be trying out these mediums again. (For more details, click on the the step-by-step images for the Still Life with Apples.)

W.F. Martin's Glazing Mediums

Earlier this year I read an online article entitled 'Glazing with Oils' by William Martin at wetcanvas.com. In this article he demonstrates the stages of a highly realistic still life painting, using 3 separate glaze mediums at different stages. I was inspired enough to want to try out these glaze mediums for myself, so I embarked on several paintings to do exactly that (see 'Still Life with Aubergine' and also two still lives in progress, both depicting a pile of books. Here are my initial findings.

'Lean' Medium: this is the first of the 3-stage medium recipes, and is made up as follows:

• 5 parts Turpentine (or Oil of Spike)
• 1 part Damar Varnish (or Venice Turpentine)
• 1 part Stand Oil

I have used this for underpaintings by mixing a little bit of medium in with each brush-load of paint. In some cases I may not have used quite enough, as the underpainting was not quite dry the following day (possibly due to using flake white ground in slow-drying poppy oil). But general I have no complaints with this medium.

'Medium' Medium (I know that doesn't sound right!) This is the second glaze recipe and is made up as follows:

• 2 parts Turpentine (or Oil of Spike)
• 2 parts Damar Varnish (or Venice Turpentine)
• 1 part Linseed Oil

Personally I chose to use spike oil and venice turpentine for my mixture, and the result is a beautiful-smelling medium! With this medium I reverted to my preferred method of applying the mixture thinly to the canvas/panel and painting into it with neat paint. I can say that of all mediums that I have used, this one is the most joyous to paint with. The paint flows so smoothly, and the surface is reliably dry by the following day, as long as the paint is not applied too thickly over the medium.

'Fat' Medium: this is the final glaze recipe, only to be used for the topost layer(s) of the painting. It is made up of:

• 2 parts Turpentine (or Oil of Spike)
• 1 part Damar Varnish (or Venice Turpentine)
• 2 parts Sun Thickened Linseed Oil

Again, I chose to use spike oil and venice turpentine, resulting in a wonderful smell. So far I have only used this on the Aubergine painting, as it is still too early to use on the books. I rubbed this medium thinly into the canvas with the palm of my hand, and then painted into it with neat paint. I enjoyed the flow of paint and the surface was fully dry after a couple of days.

So, to summarise, I think it is fair to say that these are very enjoyable mediums to use, and most suited to THIN layers of painting where visible brush strokes are not required. One thing I have noticed is that my finished aubergine painting lacks glossiness, and will need to be varnished. For more info, click on the link beneath the aubergine painting to read William Martin's full article.