Tinting Your Ground

If you like to paint on a tinted ground, the shade used is entirely up to you, but I have learned that it is hard to go wrong by using an earth tone that is complementary to the dominant colour in your painting. (E.g. - if the dominant colour is going to be red, then use a greenish earth tone; if the dominant colours will be cool, use a reddish earth tone... you get the picture).


Cennini's Pigment Suggestions
Some nice hints on coloured grounds can be found in Cennino Cennini's 'Il Libro dell' Arte' (The Craftsman's handbook). For example, in the chapter that deals with tinting paper, he includes a good verdacchio recipe as follows:

"You will make a greenish gray, or drab, in this manner. First take a quarter of an ounce of coarse white lead; the size of a bean of light ocher; less than half a bean of black. Grind these things well together in the regular way."

Or, to achieve a warmer fleshy tint, he suggests:

"half an ounce of coarse white lead; and less than a bean of vermilion. And you should grind everything together; and temper in the regular way described above."

Alternative Pigment Suggestions
To achieve a Verdacchio shade that is just a little warmer than Cennini's greenish-grey, try mixing the following pigments together:

3 parts flake white
¼ part vine black
8 parts yellow ochre
½ part burnt sienna

Applying the Tint
Whatever mix you choose, the pigments should be ground in either water or oil, according to whether you are using egg tempera or oils. When preparing a panel for egg tempera, you can mix the water-ground pigments into a solution of rabbit skin glue, and apply this tinted size over your transferred underdrawing as a final tint and size in one. For oils, you can just paint the ground coat on using thinned down oil paint as usual. But in either case, you should be able to see your line drawing through the base coat.

This picture shows a panel tinted for egg tempera... this colour mix is based on the alternative (warmer) verdacchio suggested above, though a little heavy on the yellow ochre.


This picture shows a panel tinted for oils... in this case I have just used a thin coat of raw umber.

Note that these tints can be used just as well on canvas, it is just that my examples on here relate to panels.

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Transferring a Drawing to a Panel

In several of my works on panel, I have started out by transferring a line drawing to guide my underpainting. There are various well known methods for doing this, including pouncing, gridding up or even using a projector. The method below is another highly effective way of doing it, taught to me by David Cranswick (www.davidcranswick.com).

Step 1 - Prepare the line drawing

1. Start by carrying out a fairly accurate drawing of the image that you are about to paint.
2. Now take a piece of tracing paper and trace over the main lines of your drawing, including all of the detail that you want to transfer to the panel.
3. Flip the tracing paper over and, using your fingers, rub in some dried pigment until it has fully settled into the grain of the paper. (Note that tracing paper has a good 'tooth' for holding the pigment). In the pics below I am using burnt sienna pigment.)

Step 2 - Transfer the Line Drawing

1. Take a panel that has been fully prepared with gesso and tape the tracing paper firmly over the panel, pigment-side down.
2. Now re-drew over all of your lines with a sharp, firm pencil. This step is like magic... when the paper is lifted, the drawing lines will have transferred to the panel, but amazingly the rest of the pigment all seems to stay in place on the tracing paper without imparting smudges.
3. In order to 'set' the transferred lines onto the panel, you now need to paint over them with a fine sable brush, using a solution of 1 part egg yolk and 3 parts vinegar (or you could use some thin paint medium).
4. If any of your lines have not transferred successfully to the panel, or are a little faint, you can add some dried pigment to your egg mixture and strengthen the lines with your brush.

Step 3 - Seal the Panel

Now that the line drawing is transferred, it is a good idea to size the panel one last time before starting to paint in oils. (A couple of coats of thin-strength rabbit skin glue is ideal).

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Preparing a Traditional Gesso Panel

The traditional gesso I refer to here is not the same as the modern tubs of acrylic 'gesso' (the stuff that most modern canvases come ready-primed with). In fact, traditional gesso is only suitable for use on hard surfaces like wood, mdf or metal. If you apply it to canvas or any bendy surfaces, it will crack!

Why Bother with Gesso?
The answer to that is best found by trying it out for yourself. If you enjoy working on a super-smooth, luminous surface, then gesso is for you. But if you like the relative 'tooth' of canvas, then it probably isn't. One thing to be aware of is that there is a little hard work involved. Each panel needs many layers of gesso, before being sanded, so my advice is to work in bulk and gesso a whole stack of panels in a weekend if you can.

What you will Need:

1. One or more solid panels (e.g. wood, mdf, masonite, copper)


2. A bag of rabbit skin glue granules


3. A bag of powdered whiting (aka chalk)


4. A bain marie (or a pan of water with a bowl suspended in it)


5. A wide, flat brush (or specialist gesso brush)

Step 1: Size the panel:
Wood surfaces require sizing with 3 coats of rabbit skin glue before applying the gesso. If the glue layers are omitted, the gesso will crack.

1. Measure out 1 part rabbit skin glue granules (by volume)


2. Measure out 15 parts cold water


3. Cover the granules with just an inch of the cold water and leave for 30 mins to soften.


4. Now add the rest of the water & warm the mixture gently in a bain marie, stirring until all of the glue is dissolved. Do not allow the mixture to boil.


5. For the first coat, take a small amount of the mixture aside into a separate container and add equal parts warm water, to produce a weakened 30/1 strength glue.


6. Paint the first coat onto the panel.


7. When dry, paint the 2nd & 3rd coats using the stonger 15/1 glue mixture.

Note - the glue forms a jelly when cold, so it should be kept lukewarm if possible.

Step 2: Add a Muslin Layer (optional)
If wood or plywood is used for the panel there is a risk of cracking over time. To avoid this, a layer of muslin can be stuck to the surface of the panel over the 3rd layer of glue, and then another layer of glue added. This is not required when using MDF.

Step 3: Prepare the Gesso

1. Measure 2 parts whiting (by volume)


2. Measure 1 part of the ready-prepared warm glue mixture (at 15/1 strength)


3. Before combining the two, add a small amount of warm water to the whiting, and stir to achieve a consistency similar to thick yogurt


4. Slowly stir in the glue until fully incorporated, and the texture is smooth & creamy


5. If the mixture starts to cools down and thicken during use, heat it gently in a bain-marie to maintain a warm temperature and a smooth consistency.
   

Step 4: Apply the Gesso

1. Apply the first coat to the panel using a flat wide brush, or a specialist gesso brush. Use rapid, gentle strokes, spreading an even amount of gesso over the whole of the panel, right to the edges. Avoid ‘going over’ your strokes repeatedly.


2. Apply the second coat when the first coat is 90% dry. Brush in the opposite direction to your first coat, using the same brisk, gentle brush strokes, so as not to disturb the layer beneath.


3. Continue like this for at least 7 coats – (I often do 12 coats) allowing the panel to dry to a dull surface in between each coat, and always brushing in the opposite direction to the previous coat.


4. Every now and then run the brush around the edges of the panel, to cover the sides evenly and avoid a build-up of drips.
   
   Tips:
   Keep gesso suspended over hot water to stay warm
   Never touch the wet surface with your fingers
   Do not try to speed-dry the panel over a heater - it will warp.

Step 5: Sand the panel
When the gesso is fully dry (ideally having been left overnight), you can sand the panel, ideally using a super-smooth 320 or 400 grit sandpaper. When finished, the panel should feel like silk!

Step 6: Seal the Panel (for oil painting)
Traditional gesso is absorbent so, before using with oils, it needs sealing with a couple of final layers of rabbit skin glue at 30/1 strength. Paint on this layer after the sanding is completed. (Note: This step is not required when working with egg tempera).

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