Among oil painters, there seems to be a common misconception that glazing is some kind of mystical technique that only a few can master. The basic process is, however, very simple. Glazing is putting one layer of paint over another so that you can see the underlayer through the upper layer of paint. Glazing is a form of indirect painting, which just means that you are painting with more than one layer, allowing previous layers to dry before you add more paint on top.

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.

If you are just starting out with oil paint, I have some advice.

First, be realistic. Don’t think you’re going to make any masterpieces any time soon, and never think that there are any shortcuts. If you just want to play around and don’t care about developing real skill, then just do that and have a good time. But if you are serious about learning to paint well, realize this: while it’s not that difficult to learn how to make mediocre paintings that your mom will like (or tell you she likes), making good paintings is hard—really hard. It takes a lot of practice, regardless of talent, to learn how to paint well. You will make many bad paintings before you make your first good one. If you are someone who can’t stand to be bad at something, over and over, before you get good, then oil painting isn’t for you. Maybe you should try video games. You can find cheat codes for many of them that will make you invincible.

Second, keep it simple. It’s counter-productive to plan complicated projects until you have the skill to pull them off. Your subjects, to start off, should be simple. An egg, a mug, a tree. No people. No copying photos. Your goal, to start out, should be to do some bad paintings that no one will want to look at. If your goal is to make bad paintings, it won’t be too hard to get there. After ten of those, you can start to think about paintings that are…less bad. You’ll learn more, in the same amount of time, by making several simple bad paintings than by making one complicated bad painting.

Third, there is no reason to start out by spending a lot of money or getting fancy with materials. Get a few tubes of decent, artist-grade paint. Don’t get student grade, don’t buy a beginner’s painting set, and don’t buy water miscibles or other convenience oil paints. A good starter palette would be titanium white, ultramarine blue, burnt sienna, raw sienna, and ivory black (you can get these from Robert Doak for well under $40—but don’t let him sell you anything else). Those pigments are all inexpensive and non-toxic (not that you should eat them). You won’t be able to make bright, high chroma paintings with this simple palette, but that’s a good thing: until you learn to mix neutral colors, a high chroma pallete would only force you to make luridly nasty paintings. Get some small primed canvases (no more than 8 × 10”) or some of those primed canvas pads. Get some brushes—I’d suggest a couple of bristle flats about as wide as your thumb and some synthetic sable (soft) flats about as wide as your pinkie (if you have particularly wide or narrow fingers, adjust accordingly). Also get a pack of cheap plastic palette knives. Get a pad of disposable paper palettes and a big roll of paper towels. For cleaning brushes, either go to the hardware store and buy some odorless mineral spirits, or go to the art store and get some linseed oil. Get a basic easel—a cheap table easel will do. If you continue to paint, you’ll be upgrading all of this stuff. If you find that you hate painting, find a niece or nephew to give the stuff to.

Fourth, learn to handle the paint. Set up your easel and a blank canvas. Squirt a little of each paint onto the edges of your palette. Make an abstract painting that doesn’t look like anything. Play around. Until you get used to oil paint, you may find that it’s sticky and hard to manage. Don’t thin your paint down to make it manageable; never add more than a tiny bit of oil or solvent to the paint. Learn how to load paint onto the brush; not too much, not too little. Learn how to make a flat area of one color that isn’t streaky (hint: don’t be afraid to scrub the paint into the canvas with a bristle brush). Learn to make definite strokes; never dab it on. Mix two colors together with a palette knife—try ultramarine and raw sienna. That makes a gray. Add some white. That makes a light gray. Try mixing every combination of paints on your palette to see what colors they make. Learn how to make darks without using black (I’ve done many paintings in which the darkest darks were a mixture of ultramarine and burnt sienna). Black is a good mixing color, but it’s of limited utility for making other colors darker. When you make a mistake, learn how to scrape the paint off with a palette knife, wipe off the remainder with a rag soaked in a little bit of solvent, and start that section over. Learn to blend two colors, laying down two adjacent tones of paint, then using a soft dry brush (cleaned every few strokes) to feather between them, gradually developing a gradation. Use multiple brushes at a time—one for each color, or at least one for darks and another for lights. Learn how to apply light paint over dark paint (or dark over light, which is harder) without having them mix more than you want to and getting all muddy. This last skill takes a very light touch and plenty of practice.

Fifth, pick a simple subject and try to paint it. You may want to start with just a painting in one color, using just shades of black and white, or burnt sienna and white. Try a painting with just ultramarine, raw sienna, and white. You won’t be able to mix every color you see, but, in fact, you can’t do that no matter how many colors you use. Don’t drive yourself nuts with arbitrary limits, but try to make your first few paintings quickly, in an hour or two each. It doesn’t matter if they are any good, and if you are trying hard to make good paintings you’ll be too frustrated to continue. Your goal is to make some bad paintings that no one but you will ever see, learning from each one. Finish a painting, put it away without thinking about quality, and move on to the next one.

Sixth, after you’ve done ten or so small bad paintings, take a look at them. Are the last ones as bad as the first ones? What have you learned to do well? What is still embarassingly bad? What do you need to learn next? Understand that your own perception of your work will tend toward either absolute enchantment or utter loathing (often with rapid swings from one to the other). Learn to appraise your own work realistically. Try looking at it in a mirror—that sometimes helps. Find someone you trust to give you honest but not excessively critical feedback (but decide for yourself whether they are right or wrong).

Seventh, save up some more money and get some more supplies. You probably want some more colors. Add them to your palette one or two at a time after experimenting with how they mix with the other colors you already use. Try some zinc white, which is much less overpowering in mixtures than titanium. Try cadmium red or cadmium yellow. Learn about pigments and choose paints that are made with only one pigment (you don’t need paint companies to do your mixing for you). Get some more brushes. Think about a better easel. Think about better surfaces than acrylic primer. Think about making some panels. Think about more complicated subjects (but not too complicated). Look at good paintings by artists you admire and think about how they might be made. Are there any painting classes you could enroll in? Read the rest of this web log, other web sites, and books to learn more about what you can do with paint.

Good luck.