Glazes have been around since the days of the Renaissance oil painters. These painters developed the technique of painting a monochromatic underpainting. Over that painting, they would apply glazes, which are very thin layers of transparent color. Imagine that the glaze is a colored film that you apply over a black and white photograph. The results of using glazes were some very beautiful, luminescent colors, that you cannot achieve using opaque colors.
The Difference Between a Glaze and a Wash
Today, painters using acrylic paints employ some of the same basics as the masters did. Acrylic glazing mediums are different than those used with oil paints. Glazing medium contains the same type of polymer binder that is used in acrylic paint. The binder in the medium ensures that your glaze adheres to your painting so that there is good intercoat adhesion.
While a wash of watered down paint is also transparent, it is not the same as a glaze. In painting on paper, washes work. On other media, they don’t. When you use a paint/water wash rather than a paint/medium glaze, you have weakened the ability of the wash mixture to adhere to the painting. Potentially that layer of wash mixture could flake off. It may not happen immediately. It may not happen for years. In my opinion, a wash used on media other than paper is the proverbial problem waiting to happen.
Mixing the Glaze
In mixing the glaze, the ratio that you generally want to use is 1 part of paint to 10 parts of glazing medium. Liquitex and Golden are two popular brands of glazing medium. To that mixture you can add some retarder to slow the drying of the glaze. You can also thin your mixture with a little water. Limit the amount of water that you use, so you don’t compromise the ability of the glaze to adhere to the paint underneath it.
You can use several different layers of glaze on a painting. If you want to add multiple colors to a painting, do not mix all of the colors together in one glazing mixture. Often the result will be a brown or muddy color. Instead, you need to apply one layer of color at a time to achieve the final hue desired. That doesn’t mean that you can’t create your own colored glazes. For example, in the photo of the poppy shown in this article I mixed a red and a blue to create a purple hue which I used in the shadows.
Selecting Paints for Glazes
In using a paint color to create a glaze, read the label of the paint tube to learn about the opacity of the paint. Some pigments are transparent. Others are semi-transparent or opaque.
In many cases, in creating a glaze, you will want to use paint with transparent pigments. This allows the underpainting to show through. The transparent colors allow transmission of light through the glaze and reflect off of the different values of highlight, midtones and shadows of the underpainting. This gives the painting a very luminescent presence.
Blues, reds and yellows tend to be the more transparent colors. I don’t want to give you the idea that you cannot use opaque and semi-transparent paints in creating a glaze. You can. Many people use earthtones, such as raw sienna, burnt sienna and yellow ocher, which are not transparent, in glazes.
Just keep in mind that if you use an opaque color in making a glaze, the result could be a hazy appearance over the base painting. On the other hand, that might be the appearance that you are trying to achieve.
If you are not sure how a particular paint will work as a glaze, you need to do a little experimenting. As I like to tell people: Test, Don’t Guess. Mix up a little glaze and try it. Then record your results in a journal for future reference. Or if you want to understand how different transparent colors look over other colors, you can create a test panel for yourself showing different color combinations.
Applying the Glaze
In applying the glaze the preferred brush among artists is one with very soft hairs. The reason is that the softer hairs will apply a very even layer of glaze without brush strokes that will level out to a nice smooth finish. The surface finish of the underpainting is also critical in achieving a uniform appearance. Preferably the surface of the painted substrate will be very smooth. If the substrate is rough or has a texture, more pigment will be deposited in the valleys of that textured surface. The result is often a blotchy appearance.
In working with acrylic glazes, you will need to work fast, because acrylic paints dry fast. Keep a spray bottle of water handy to periodically mist your glaze and paint on your palette to prevent them from skinning over.
Apply very thin layers. Before applying another layer, let the initial layer dry thoroughly. Even if you mix in a retarder and a little water into the glaze, it will tack up fast. As soon as that happens, stop working on that area and work on another area of the painting.
There is only so much that you can learn about glazes by reading or watching a video. The only way that you will truly understand what you can and cannot do is to put what you learn into practice. Only by working with different mediums and trying different concoctions will you master this technique.