David: In the beautiful work you show on your gallery, are most of the effects achieved with your “thick glazing” technique? I have been experimenting with thin glazes and have run into problems at every turn. For example: How to achieve an intense red or orange, since cadmium colors are out? How to glaze thinly and be able to do fabrics and tablecloths — especially in light colors? How to do a light color ceramic bowl (as in one of yours)? Maybe you could speak in detail about the work in your gallery…

Thanks for the kind words, Julius. Glazing is not my primary oil painting technique.* I tend to paint fairly opaquely most of the time, attempting to achieve the final look of each passage before moving to the next. I’m not dogmatic about that, however, and will go back over a passage, opaquely or transparently, if I didn’t get it right the first time.

I do use glazing for specific purposes. For example, the background of the self portrait in the gallery is yellow ochre glazed over white. Although YO is usually thought of as rather dull, its undertone has a very different character—much higher in chroma and value. That’s one great use of glazing: to avoid “chalkiness” (lowered chroma) at high values.

As far as intense red or orange, here’s how that was done historically. Start by painting that specific passage in a flat opaque color similar to your desired final hue. For example, you could use cadmium red light (historically, this would have been vermilion, which behaves similarly to cad red). Let it dry. Then glaze over it with a similar transparent color such as alizarin crimson (which is fugitive) or pyrol ruby (which is not). Make this second color thick where you want it dark and thin where you want midtones or lights. If desired, paint into the lights with the same or similar colors mixed with white. Let it dry. If the darks are not dark enough, apply another layer of glaze to those areas, perhaps darkened with another transparent color such as ultramarine blue. Over two or three layers, you can get the darks as strong as you like, in a higher chroma than you can get without glazing. I’ve tried this, and it works. For orange, you are limited in glazing colors, but hansa yellow mixed with any of the modern transparent organic reds or crimsons can work.

Does this method allow you to get any color you wish? No, it does not. You are limited to available shades of transparent pigments. But the Old Masters were even more limited, and they didn’t make junk.

As for fabrics, this method works quite well if you have the patience for it. Be prepared to go back into the lights, while the glaze layer is still wet, with opaque colors mixed with white.

Ceramics are easy. For a white ceramic glazed with blue, just paint the object without the blue and allow to dry. Ultramarine or other semi-transparent blues glazed on top are quite convincing (that’s how I did the ceramic cup in the “Three Cherries” painting in my gallery).

This would be easier to show than to tell, but I hope this is helpful.

I messed up the right sleeve. As was painfully obvious the next day, but somehow didn’t hit me at the time, the shadow color in the right sleeve is too green and too low in chroma. (This may not be clear in the photo you are looking at, as these are fairly subtle color distinctions.) Shadows elsewhere are in the orange and yellow range, assisted by the earth red tone I had applied on top of the glue-chalk gesso primer. My plan is to let let that section dry completely while I work on the rest, glaze the shadows with transparent yellow oxide and transparent red oxide, and work into that base in order to correct the color.

Other than that, I like it so far, which is rare for me at this point in a painting. It still needs a bunch of fabric detail and the hangar needs to be painted in, but it’s basically progressing well.

Glazing can be used for a number of purposes. As I noted my post comparing the glazing methods of Italian and Netherlandish Renaissance painters, glazing can be used to create optical color mixtures (a blue glazed over a yellow makes a green) or to create modeling effects (thicker layers of transparent paint are darker, so you can adjust value by adjusting the thickness of the paint). Some artists glaze over a whole painting to unify the overall tone. Others will glaze specific parts of the painting. One method is to do an initial monotone underpainting (in shades of grey, for example) then apply color over it. This simplifies the process of painting by first tackling pure value, then working out hue and chroma. Some modern portrait painters will do an initial painting of flesh in shades of green (they incorrectly call this a “verdaccio”). They then glaze with reds and oranges (complementaries and near-complementaries to green), providing the flesh tones with a sense of vitality that is difficult to achieve with direct painting. Glazing can also be useful for maintaining chroma in light colors. Mixing with a lot of white will seriously reduce the chroma of most colors, resulting in a look often described as “chalky.” If you glaze the same color over white, however, you can achieve an optical effect that is high in value, with more chroma that you could get by mixing that color with white.

Because a glaze darkens what it covers (unless its a scumble—see below), it is best to do the underpainting lighter than the intended final effect. If you are going to glaze, it’s important for the underpainting to have as smooth a surface as possible. That’s because irregularities will trap excess amounts of paint in the glaze layer, creating weird little spots of darker paint. So, before the paint dries, it’s a good idea to go over it very lightly with a soft dry brush, looking for lumps and gently brushing them down. After the underpainting has dried thoroughly, you may want to wet sand to create as smooth a surface as possible.

In selecting paint colors to glaze with, it is useful to distinguish among opaque colors (like cadmium yellow), semi-transparent colors (like ultramarine blue), and transparent colors (like alizarin crimson). While any of these colors can be used for glazing, transparent and semi-transparent colors are darker when they are put on more thickly. Opaque colors can be used for glazing, but only when they are applied in a thin layer. A thick layer of an opaque color is not a glaze, because you can’t see the underpainting through it.

Many oil painters think that the best way to glaze is to dilute the paint with medium to a watery or syrupy consistency (this is what a lot of art instruction manuals tell you to do). The paint becomes less opaque because the pigment particles are separated by a larger than normal amount of transparent vehicle. This type of glaze is called a dilution glaze. In my (deeply humble) opinion, it’s the wrong way to glaze. It’s bad technique for (at least) three reasons: (1) all of that extra resin and oil will darken and yellow over time, ruining the effect; (2) dilution glazes tend to create a sort of “tinted photograph” effect that doesn’t have the solidity a painter is usually trying to depict; and (3) the documentation I’ve found on historical glazing techniques suggests that only small amounts of resin are detected in glazing layers in Renaissance Netherlandish paintings, which I consider to be the gold standard in glazing for both beauty and longevity.

A better method is called a reduction glaze. This approach involves adjusting the transparency of the paint by adjusting the thickness of the paint layer. While you can do a reduction glaze with nothing but pure oil paint, it helps to first lubricate the surface by applying a very thin layer of a slippery medium. My preferred glazing medium is a 50/50 mixture of black oil (linseed cooked with lead) and Venice turpentine (if you don’t like to use substances containing lead, linseed oil will work almost as well). Studio Products also sells an excellent glazing medium. You can also use plain linseed or walnut oil as a glazing medium. Put a drop of medium on the surface, rubbing it in with your fingers to spread it as far as possible. This way, you can cover a large area with just a few drops of medium. In addition to putting some on the surface, you can also put just a tiny bit of medium in your paint, but I don’t usually find that necessary.

Mix up the color you want to glaze with. Apply it thickly and evenly to the desired area with a brush. It will look like a horrible mess at this stage, but have faith. You will now reduce the thickness of the glaze to the desired opacity and value. Do this by dabbing with a soft brush, smearing with your fingers, rubbing with a cloth or sponge, or whatever works to adjust the glaze to achieve the desired effect. With a little practice, a reduction glaze is really pretty easy. You can get nice gradations in color and value by creating a gradation from thin to thick. Or you can create gradations from one color to another. Once you have the glaze spread to the right thickness, you can, if you like, paint into it with other colors. For example, you can apply light highlights into a wet glaze and then blend it in. If desired, you can let your glaze dry and then add one or more additional layers of glazing. For example, you can get really intense, chromatic darks by glazing with multiple layers of transparent paint.

When mixing colors for a glaze, it is sometimes helpful to add a small amount of white to your mixtures. This provides a greater sense of solidity.

If you glaze with very light colors containing a lot of white, it is usually called a scumble. Titanium white, being very opaque, can be a bad choice for scumbling. Flake white and zinc white are much easier to create transparency effects with. A very white, hazy glaze is called a velatura (“veil”). A velatura can be a great way to depict transparent smoke, haze, or fog.

Update

Instead of making sure the underpainting surface is smooth before glazing over it, you can deliberately give it lots of texture. Then the glaze will sink into the nooks and crannies, creating a sense of dimensional relief. Rembrandt often used this technique.

By layering, I mean variations on glazing. I am using that term broadly to mean any application of two or more layers in which the layers beneath contribute to the final visual effect. Glazing can be done with relatively transparent colors such as red lake, or with opaque colors such as vermillion (if it is applied thinly enough). In both the Netherlandish and Italian traditions, glazing was critical to the final appearance of important parts of almost all paintings, but the way they used glazing was different.

In Netherlandish painting, glazing was used to adjust values with minimal loss of chroma. Typically, an opaque color, such as vermillion, was applied first. The initial layer was typically flat—i.e., with no attempt to model the forms. Then a transparent pigment of similar hue, such as red lake, was applied over the initial flat layer. The transparent color was applied thinly in light areas and thickly in dark areas. Often multiple layers were applied to darks. Because thicker layers of transparent pigments absorb more light than thin layers, a thick layer is darker than a thin layer. This approach to modeling, in which darks are created not with darker colors, but with thicker, light-absorbing layers, creates an optical effect that is completely different than simply mixing a light, a midtone, a dark, and then blending them. Blacks and other dark, dull colors were avoided in Netherlandish glazing. Fully-modeled objects have a jewel-like tonality that jumps off the picture. This glazing technique wasn’t used throughout the painting, but was carefully applied in order to control the structure of the composition. It was not used in modeling flesh tones, which were typically done very thinly, in one or two layers.

In Italian painting, by contrast, glazing is used to generate hues through optical mixing of layers. For example, in early Renaissance Italian tempera painting, flesh tones are created by first applying a layer of dull green, then modeling in a dark dull brownish green. On top of that, the flesh color is created by applying an opaque pink (flake white mixed with vermillion) thinly enough that the underpainting shows through. Later in the Renaissance, when Netherlandish oil paintings began to be imported, the Italians tried to copy those effects in oil paint. But while they knew how to make oil paint, they didn’t know about Netherlandish layering. They created darks by mixing dark dull colors, including black. Italian oil paintings from that period show none of the chroma intensity in the darks that make Netherlandish paintings so special. It wasn’t that they were stupid; it was that they thought about color and layering in a different way, and that approach created a different set of effects. The Italian method was also useful. Botticelli, for example, underpainted foliage with black before glazing over with greens. This makes the foliage fade into the background. He underpainted flesh with yellow ochre, to make flesh tones that had a warm cast. Michelangelo used a traditional (and then somewhat old-fashioned) underpainting with greeen earths for flesh tones. If he wanted two different tones of blue drapery in a painting, he would underpaint one with black, then ultramarine mixed with varying amounts of white and black. The other would be done in the same set of ultramarine gradations over white gesso, creating two completely different ranges of blue with the same surface pigment. Leonardo’s sfumato method involved a very dark underpainting in dull earth tones, followed by glazing with light colors mixed with a lot of white. Italian painting is generally brighter and more chromatic than Netherlandish painting, but the darks are more dull. The eye picks up on these differences very easily.

It’s useful to understand how both of these kinds of layering effects are accomplished, because if you know how to do both, you have a broad range of useful tricks.