Pebeo linen canvas and impasto gels - "Afloat" WIP1-2
Ever wondered how to layer acrylic gels to get a thick, layered, translucent water-like quality? How do you avoid the previous layer 'coming back up' or 'opening'? What is the difference between the 'heavy' and 'regular' gels?
I'm starting a new painting of a platypus to test some new techniques and acrylic mediums, and using for it a photo of a floating platypus which I took at Eungella National Park (1hr drive west of Mackay in QLD, Australia). One characteristic I really wanted to capture in the painting was the depth and green colour of the water.
I decided to use a Pebeo natural linen canvas board because they have a beautiful and varied neutral brown colour in the linen fibres, and I wanted some of this background texture to show through the edges of the painting.
When using Pebeo linen canvas (which has a 'universal clear primer' already applied) with Atelier acrylics, it is necessary to first seal the surface with their Atelier 'binder medium'. Without the binder medium being applied first, although my first layer of paint went on smoothly, as soon as it was semi-cured and I added more paint, the entire first layer 'lifted off' the canvas (and became a million tiny wrinkles of paint sitting on the surface - effectively a big sodden mess)! I should have taken a photo at the time it happened, but as you can probably guess, it was very disheartening to lose all the progress I had already made! :)
Anyway, after applying the binder medium to a new fresh canvas and allowing it to dry completely, the first step with this platypus painting was to add some three-dimensional shape to the animal itself. I did this with Atelier modelling compound, and allowed it to dry, after which I painted it a base-coat of brown.
Then came the challenge of what to do with the background and all those beautiful greens I could see in my photo and wanted to emulate on the canvas. So I decided to try both heavy and regular gel mediums (see Fig. 1).
Atelier heavy gel (gloss): As you can see from the photo (Fig. 1), the heavy gel is a thick white creamy substance which readily holds peaks and troughs when scooped and mixed with a palette knife. It is thicker than the paint pigments themselves, and when mixed with small quantities of paint, the mix will become a paler milky version (WIP 1) of the original colour (although the gel itself dries clear, so this milkiness will disappear; see WIP 2). Heavy gel is good for impasto painting (brush or palette knife) where you want to keep textural marks and structure. The finish 'gloss' implies that there is no matting agent in the gel, and hence the appearance will be glossy.
Atelier regular gel (gloss): Regular gel on the other hand is much more fluid with a smooth consistency, moreso even than the paint pigments themselves, and it tends to slide off a palette knife. While it can be used to impart impasto effects when mixed with colours, it is slightly self-leveling and won't retain sharp peaks. Similar to the heavy gel, it imparts a milky or cloudy appearance when wet-mixed with colours, and this milkiness dries transparent. The finish is glossy.
But, as usual, there are some things the manufacturers don't tell you:
If you plan to use multiple layers of gels (or gels mixed with coloured pigments), then you should use 'fast medium/fixer' between layers. This is crucial because gels take longer to cure than ordinary thin paint applications, and without the fixer, the new layer 'opens' the underneath layer (enough to move it around inconveniently on your canvas and produce undesirable pigment clumping). This 'opening' effect can take a little while, so when you first apply the second layer it might seem fine, until you start trying to blend it in. You can see where this pigment clumping has occurred in WIP 2.
Gels provide a difficult surface to paint on with ordinary pigment acrylics. So if you're planning to use the gel for texture underneath a painting, be aware that you will need to cover it with fixer medium first. It isn't impossible to paint on the surface, however the paint will tend to slide off the surface (particularly if diluted with water rather than clear painting medium), and in particular, any further interaction with the surface even after the paint layer has cured can rub the paint straight back off again.
The milkiness of the gels when mixed with coloured paints can make it very difficult to judge the 'clear' end result, especially how well blended the layer is. You can clearly see the difference if you compare WIP 1 with WIP 2. The gel layer is still wet (and milky-appearing) in WIP 1.
If you're using gels to achieve translucent effects (such as deep green water as I was attempting with the platypus painting here), you need to be very aware of the transparency or opacity of the colour pigments you're mixing with it, and the ratios of gel to paint that you're mixing (even with pale colours where it might not be apparent against the white of the gel to start with). In my platypus painting experiment, the yellow colour (naples yellow) is considerably more opaque than the forest green and olive greens, which meant that much less of the yellow was needed to obscure the background linen colours/textures. It's a good idea to test this on a coloured background before you start on your proper canvas.
If you need to alter the opacity of a transparent pigment, in order for it to appear similarly translucent to your other gel/paint mixes, then you can try small amounts of tinting white. Tinting white also imparts a subtle opalescent quality to the dried surface.
Anyway, as you can see from the work in progress shots of the platypus painting (WIP 1 and 2), before I worked out these tips, the first layers of gel and pigment used in the background weren't quite having the effect I was after (the pigment was too clumpy due to the upper layers 'opening' the lower layers of gel/pigment). So I decided to keep layering in an attempt to even-out the pigment and translucency.
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