Glazes and Glazing in Oil Painting:
Glazing is one of the most powerful and traditional oil painting techniques artists use to achieve depth, luminosity, and rich color transitions. A glaze is a thin, transparent layer of darker oil paint applied over a lighter opaque or transparent underpainting. Because the glaze is clear, the color underneath shines through, creating a vibrant optical blend instead of a flat physical mixture.
This effect is similar to placing a colored sheet of cellophane over another color. The result is a glowing, layered surface that cannot be achieved by direct body-color painting or by mixing colors on the palette.
Professional artists sometimes introduce tiny amounts of opaque or semi-opaque pigments into their glazes. This softens excessive brightness, increases solidity, and still allows the underpainting to remain visible.
What Makes a High-Quality Glaze Medium?
A proper oil painting glaze medium must meet several essential requirements to ensure permanence and excellent handling qualities.
1. Smooth Handling
The medium should brush out evenly without feeling overly oily or sticky. A balanced feel allows controlled manipulation.
2. Permanence
Only stable, time-tested materials should be used. This ensures long-term durability and avoids cracking or discoloration.
3. Reasonable Drying Time
Most artists prefer glaze layers that dry overnight, making it easier to build multiple layers efficiently.
4. No Solvent Action on the Underpainting
A good glaze medium should not disturb, lift, or dissolve the dried paint layers beneath.
5. Resistance to Future Layers and Varnish
Each glaze must remain stable during the application of later coats and during varnishing.
6. No Running or Sagging
A correctly formulated medium should not drip or slide on a vertical easel surface. Detailed glazing is often done with the painting laid flat.
7. Flexibility
The dried film must remain flexible enough to match or exceed the elasticity of the underpainting.
Because no single oil or varnish meets all these requirements, artists rely on carefully blended glaze mediums. Many commercial painting mediums remain controversial because manufacturers rarely reveal their formulas. Some contain unstable ingredients such as outdated driers, raw or oxidized oils, or inferior synthetic resins.
For this reason, many professionals prefer to mix their own glaze mediums and avoid adding unnecessary materials to every layer of oil paint. Not all oil painting requires medium—some of the most archival works use very little.
Glazing vs. Scumbling: What’s the Difference?
Glazing
Transparent
Darker color over lighter underpainting
Highly controlled
Used for depth, richness, and subtle transitions
Scumbling
Thin, lighter layer over darker underpainting
More opaque or semi-opaque
Looser, more textural
Often used to soften large areas or adjust tone
Scumbling can be applied with a brush, rag, dabber, or even fingertips, depending on the level of softness desired. It typically works best over paint that is dry to the touch or over an isolating varnish.
How to Glaze in Oil Painting: Professional Techniques
Artists use several methods depending on the desired effect:
Brushing on a thin transparent layer
Stippling with a blunted brush
Blending with a badger-hair blender
Using a pad or dabber for smooth, flawless surfaces
For sharp, polished realism, a careful, deliberate approach is required. For expressive, looser styles, the same principles apply but with more freedom.
Creating Smooth Color Transitions (Skies, Backgrounds, Skin Tones)
Large areas requiring seamless gradations—such as skies, backgrounds, fabric, or skin—benefit from thoughtful preparation:
Prepare all your glaze tones before starting
Many artists underestimate how many transition colors they need. Beginners usually require twice as many tones as expected to achieve smooth blending.
Keep mixtures clean
Your glaze mixtures must be free of dried skins, lint, dust, or impurities that can cause streaks.
Work while the glaze is still wet
Most blending must be done before the first layer begins to set. If one glaze contains more liquid, it may pick up the layer below, so consider applying the darker glaze first.
Ideal consistency
A glaze should be:
Well-pigmented
Soft and paste-like
Spread thinly through application—not over-thinned with liquid medium
Overly fluid glazes can drip, apply unevenly, or dry with a weak finish. A tiny amount of pigment in a “watery” medium often looks streaky and unattractive.
The most effective method is applying a thin, soft layer of paint and then refining it through:
Stippling
Tamping
Dabbing
Wiping back selectively
This produces the classic, luminous look associated with traditional Old Master glazing techniques.
Conclusion: Why Glazing Matters
Glazing is one of the most powerful oil painting techniques for achieving:
Depth
Luminous color
Smooth gradations
Realistic shadows
Atmospheric effects
Rich, professional finishes
With a well-balanced glaze medium and thoughtful application, artists can create paintings with unparalleled brilliance and subtlety.
Frequently Asked Questions
What is glazing in oil painting?
Glazing is the application of a thin, transparent layer of oil paint over a lighter, fully dried underpainting. Because the glaze is transparent, the underlying color remains visible, creating depth, luminosity, and rich optical color effects.
Why does glazing produce more luminous color than direct mixing?
Glazing creates an optical blend, where light passes through the transparent paint layer, reflects off the lighter surface beneath, and returns to the viewer. This produces a glowing effect that cannot be achieved by physically mixing colors on the palette.
Can opaque pigments be used in glazes?
Yes. Small amounts of opaque or semi-opaque pigments may be introduced to soften excessive brightness or add solidity, provided the layer remains thin and transparent enough for the underpainting to show through.
What qualities should a high-quality glaze medium have?
A good glaze medium should handle smoothly, remain permanent and stable, dry in a reasonable time, avoid disturbing the underpainting, resist future layers and varnish, avoid sagging, and dry to a flexible film.
Why is solvent action on the underpainting a problem?
If a glaze medium dissolves or lifts the underlying paint, it can cause muddiness, color contamination, or long-term structural weakness in the painting.
How long should glaze layers take to dry?
Many artists prefer glaze layers that dry overnight. This allows efficient layering while maintaining control and reducing the risk of disturbing previous layers.
Is it necessary to use a glaze medium in every layer of oil painting?
No. Many durable and archival oil paintings use very little or no added medium. Glaze mediums should be used only when their specific properties are needed.
Why are some commercial glaze mediums controversial?
Many commercial mediums do not disclose their full formulations and may contain unstable ingredients such as outdated driers, raw or oxidized oils, or inferior synthetic resins that can compromise longevity.
Why do some professional artists mix their own glaze mediums?
Mixing custom glaze mediums allows artists to control permanence, drying time, flexibility, and handling, while avoiding unnecessary or unstable additives.
What is the difference between glazing and scumbling?
Glazing uses transparent darker layers over lighter underpainting to build depth and richness. Scumbling uses thin, lighter, more opaque layers over darker paint to soften, adjust tone, or add atmosphere.
When should scumbling be applied?
Scumbling works best over paint that is dry to the touch or over an isolating varnish, and is typically applied loosely with a brush, rag, or dabber.
What tools are commonly used for glazing?
Artists glaze using soft brushes, stippling brushes, badger-hair blenders, pads, dabbers, or cloths, depending on the desired level of smoothness and control.
How can artists achieve smooth color transitions with glazes?
Smooth transitions require preparing multiple intermediate tones in advance, working while the glaze remains wet, and blending carefully using stippling, tamping, or gentle wiping.
What is the ideal consistency for a glaze?
A glaze should be well-pigmented, soft, and paste-like, spreading thinly through application rather than excessive dilution with liquid medium.
Why are overly fluid glazes problematic?
Over-thinned glazes can drip, streak, apply unevenly, and dry with weak or unattractive surfaces. Thin application should come from brushing technique, not excess liquid.
Should darker or lighter glazes be applied first?
Darker glazes are often applied first because they are easier to control and less likely to pick up lighter layers beneath them.
Why is glazing often done with the painting laid flat?
Working flat prevents sagging or running and allows greater control over thin, detailed glaze layers.
Why is glazing considered essential in traditional oil painting?
Glazing allows artists to achieve depth, luminous color, realistic shadows, atmospheric effects, and refined surfaces that are difficult or impossible to achieve with direct painting alone.