Techniques

Oil Painting Rules
When painting with oil colour, artists must adhere to three conventional oil painting rules:

  1. Fat over lean  – Fat over lean is better understood if considered as ‘flexible over less flexible’. When painting in layers, the proportion of medium used in each layer should be increased. The higher proportion of medium makes subsequent layers more flexible and prevents the painting from cracking. This rule has traditionally been kept by adding more and more oil to the solvent used. However, as Liquin is now more commonly used, it is the Liquin content which is increased. There is no need to use oil as well.
  2. Thick over thin – Thick layers of oil colour are best applied over thin under layers. Thin layers on impasto paintings are likely to crack.
  3. Slow vs. fast drying colour – Slow drying colours should not form continuous under layers as any faster drying layers on top may crack.

Oil Painting Techniques and Effects

Artists can create a multitude of painting effects with the use of mediums. Below are a few illustrations which explain how they work and hopefully inspire you to try them out.

 Glazing

Glazing
Glazing is the build up of layers of transparent or semi trasnparent colour over dry underlayers. It is a lengthy technique where the effects in oil are unmatched when compared to other media. Liquin original is an excellent glazing medium and will reduce brushmarks. The new Blending & Glazing Medium is also ideal for this purpose.

 Scumbling

Scumbling
Loosely brush a thin film of opaque or semi-opaque colour over your underpainting. This may actually show through in places and can retain an important influence on the surface appearance of the painting. Liquin can be used to thin the colour or if you prefer a thick texture, use Liquin Impasto or Liquin Oleopasto

 Stipple

Stipple Effect
A bristle brush and thick viscous colour can create a “stipple” texture. Tube colour alone will work well or colour mixed with Liquin Oleopasto.

 Scraping back  

S’graffito
“S’graffito”, the technique of scratching into a wet oil film, can be done with the pointed end of a brush, painting knife or any scraping device.

It is effective in defining outlines or details for expressive effects. If you want more time for scraping back the colour you can slow the drying by using Refined Linseed Oil or Artists’ Painting Medium with the colours.

 Impasto  

Impasto
This is the technique of applying paint thickly, so that the brush strokes are plainly visible and create a textured effect.

Liquin Oleopasto will add texture and increase the transparency. For thick impasto, build the texture in several layers allowing each to dry first.

 Underpainting  

Underpainting
Many artists complete the underpainting ofa project in faster drying colour (such as Griffin Fast Drying Colour) to save time and then go on to complete it with conventional colour.

Underpainting can be done in monochrome using any colour, or it can be done in full colour if using fast drying colours.

Direct –

you mix the exact color you want on the palette, then brush it onto the canvas, where it stays wet.  You can then alter the hue by brushing a 2nd color over the 1st and mixing them right on the canvas.  You can pile thick color over thin without waiting for the first layer to dry.  You can cover one color with another or scrape off a color to reveal what’s underneath.


Correcting Oil Paintings:

1. Scraping & Re-painting – When you scrape off some unsatisfactory section of the painting, you won’t get down to bare, white canvas.  The knife doesn’t take off every trace of wet paint, but leaves a “ghost” of that tree you wanted to move or that rock you wanted to delete.  This is no problem.  A fresh layer of color will easily cover what’s left of the underlying paint.  In fact, that “ghost” has two advantages.  Just a faint trace of wet color on the canvas will actually make your brush move more easily over the painting — it can be a very pleasant surface to work on.  And that pale image can serve as a helpful guide for your brush to follow.
2. Wiping & Re-painting – Of course, many artists find that “ghost” image distracting.  When they want to make a change, they prefer to eliminate as much of the underlying image as they can.  Then the solution is to take a tough, lint-free rag, dip it in turpenoid, and scrub away the wet color.  If the paint is fairly thick, it’s a good idea to scrape first with a palette knife.  This takes off all the paint that sticks up from the surface.  After the scraping, you can use the rag and solvent to dig further into the fibers of the canvas and get rid of the “ghost” that’s left by the scraping.
3. Repainting a Dry Canvas – What if the picture has sat around the studio for a week or more — which probably means that it’s now dry to the touch?  You can’t remove the image easily, but it is easy to paint over the dry surface.  Start by working over the surface gently with fine sandpaper or steel wool; this will take off some of the paint and roughen the surface slightly so that it becomes more receptive to new brushwork. Then, it’s a good idea to moisten the surface with just a bit of medium.  Dip a clean, lint-free rag in your medium, and wipe the rag over the area you expect to repaint.  The canvas should be slightly moist, giving you the pleasant sensation that you’re working on a wet painting.  But the canvas shouldn’t be so wet and shiny that the brush slithers over the surface and the bristles don’t dig in; if the canvas seems too wet, wipe it gently with a dry rag, leaving the surface just faintly moist.
Varnishing –
1. Retouching Varnish – This is a thin mixture of solvent and a little resin such as damar or mastic.  The solvent evaporates, leaving behind just enough resin to preserve the freshness of the colors — and perhaps brighten the colors a bit — while the paint film continues to dry.  Apply retouching varnish with a soft nylon housepainter’s brush.  Work with parallel strokes, and don’t scrub back and forth (the paint isn’t as dry as it looks).
2. Final Varnish – Often labelled ‘picture varnish’, this is a thicker version of the same formula used to make the retouching varnish, but it has more resin.  You’ll want to wait 6-12 months before applying this varnish.  Again, use a soft nylon housepainter’s brush and work with parallel strokes.  Move the brush in one direction only — from top to bottom or from one side to the other.  Work on a clean horizontal surface, and leave the painting there until the varnish dries to a smooth, glassy film.
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