The Fat Over Lean Rule in Oil Painting: Explained

Oil painting is a versatile and popular medium that has attracted artists for centuries. One of the most important rules to understand and follow when working with oil is the “fat over lean” principle. This principle ensures the longevity, flexibility, and overall stability of your oil paintings.

How The Fat Over Lean Rule Works

The “fat over lean” rule refers to the order in which layers of paint are applied to the canvas. It is based on the fact that oil paints consist of pigment particles suspended in a drying oil medium, traditionally linseed oil. The drying oil oxidizes and hardens over time, creating a solid surface. However, improper layering of paint can lead to cracking or other structural problems in a work of art.

Simply put, the rule of thumb is that each successive coat of paint should contain more oil than the previous one:

1. Initial coats, known as “lean,” contain less oil and more solvent, making them thinner in consistency. These lean coats provide a firm base and promote adhesion between the paint layers and the support;
2. As you move toward the top coats, called “fat” coats, the oil content increases, making the paint fatter and fuller in consistency. Oily layers dry more slowly than lean layers, and their increased flexibility prevents cracking. The thick over lean approach allows the painting to deform without stressing the layers below, which increases the longevity of the artwork;
3. To achieve the “fat over lean” principle, artists can adjust the oil content by adding oil mediums or diluting the paint with solvents. Using oil mediums, such as linseed oil or poppy seed oil, increases the oiliness of the paint. Conversely, solvents such as mineral spirits or turpentine reduce the oil content, making the layers more fluid;
4. It is very important to watch the drying time between coats, as applying a fat coat on top of a still-lean coat can lead to problems. Waiting for each layer to dry to the touch or using quick-drying mediums can help maintain the integrity of the “fat over lean” approach.

Understanding the “fat over lean” principle is especially important when working in multiple sessions or when using traditional staining techniques. Following this rule ensures that the top layers of paint do not compromise the stability of the lower layers, allowing the painting to age gracefully.

By adhering to the “fat over lean” rule, artists can create oil paintings that not only have vibrant color and rich texture but also stand the test of time. This principle ensures the right balance of oils and solvents in each layer, contributing to the adhesion, flexibility, and longevity of the artwork. Embrace this fundamental rule in your oil painting practice and let it guide you to a mastery that will last for generations to come.

What is lean paint?

In oil painting, lean paint refers to a mixture of oil paints with less oil and more solvent than other layers of paint in an artwork. Oil paint is notable for its thinner consistency and faster drying time.

Rules for using lean paint

When making lean paint, artists usually use more solvents, such as mineral spirits or turpentine, to thin the oil paint. This dilution reduces the amount of oil in the mixture, resulting in a thinner paint layer. As a result, the paint layer dries faster and has a more matte appearance. To do this:

• Thin coats of paint are often used in the initial stages of oil painting, serving as an undercoat or base coat;
• They provide a solid base for subsequent coats of paint and create a smooth surface for further work.

By using lean paints in the early stages, artists can define the composition, values, and overall structure of their work.

It is important to note that layers of lean paint should be applied thinly to prevent cracking or other problems as the painting ages. These coats should be stiffer and provide a solid base for subsequent coats, which will have a higher oil content and greater flexibility.

In general, lean paint plays an important role in the fat over lean” rule in oil painting. By starting with lean coats and gradually increasing the oil content in subsequent coats, painters can ensure the stability and durability of their works while achieving the desired effects and textures.

What is fat paint?

In oil painting, fat paint refers to a mixture of oil paint that has a higher oil content and a lower solvent content than lean paint layers.

Features of fat paints:

• Oily paints have a thicker consistency and a slower drying time;
• When creating bold paints, artists usually use a higher proportion of drying oils, such as linseed oil or poppy seed oil, to increase the oil content of the mixture. The result is a more viscous layer of paint that retains moisture and takes longer to dry;
• Bold layers of paint are usually applied in the later stages of an oil painting, layering on top of lean layers that create a firm base. Bold coats are used to give depth, texture, and richness to a work. They can be applied in strokes or with a palette knife, creating an impasto or smooth glaze effect;
• Higher oil content in fat layers of paint offers several advantages. It increases the flexibility of the paint film, reducing the risk of cracking over time. Oily coats also have a sheen after drying, which increases the visual appeal of the painting. In addition, the increased oil content makes it easier to mix and manipulate paints on the canvas;
• When using bold coats of paint, consider drying time and interaction with underlying layers. Applying a fat coat on top of a lean coat that has not yet dried can lead to problems such as cracking or poor adhesion. Painters often wait until the underlying layers are dry, or use quick-drying products to ensure proper layering and maintain the “fat over lean” principle.

By strategically placing the right layers of bold colors in oil painting, artists can achieve a variety of effects, from thick and textured impasto to smooth and translucent glazes. These layers contribute to the overall richness, depth, and vibrancy of the artwork, creating a visually arresting result.

Remember that when working with oil paints and related media, proper ventilation and caution are essential. Always follow safety procedures and use proper ventilation to ensure a safe and healthy working environment.

Why follow the fat-over-lean rule?

Following the “fat over lean” rule in oil painting is necessary for several reasons. Let’s look at why following this principle is critical to the longevity and stability of your work:

• Adhesion and stability: The “fat over lean” rule ensures proper adhesion between layers of paint and support (canvas or panel). Thin coats containing less oil and more solvent provide a firm base for subsequent coats. This prevents the top layers from peeling or flaking over time;
• Flexibility and crack prevention: Oily coats with high oil content dry more slowly and remain more flexible than thin coats. This flexibility allows the paint film to expand and contract without cracking as the environment changes, such as temperature and humidity. By gradually increasing the oil content of each layer, you can adapt the painting to these subtle movements;
• Managing drying time: Thick layers of paint dry more slowly than thin layers. By following the “fat over lean” rule, you allow each layer to dry sufficiently before applying the next. This helps avoid problems like top coats drying faster than bottom coats, which can cause cracking or adhesion problems;
• Structural integrity: Proper layering according to the “thick over lean” principle helps maintain the structural integrity of the painting. Thick layers on top of thin layers create a stable and consistent color film. This is especially important when using traditional glaze techniques or when painting in several sessions over a long period of time;
• Visual Effects and Saturation: By using thin layers as a base and building up thick layers, painters can achieve a variety of visual effects. Bold layers provide depth, texture, and saturation to the artwork. The thicker consistency of bold paints allows for impasto techniques and exciting brush strokes or palette knife textures.

Ultimately, following the “bold paints are better than lean” rule ensures that your oil painting will age gracefully, maintaining its visual appeal and structural integrity over time. This minimizes the risk of cracking, delamination, or other problems that can compromise the quality and longevity of the artwork.

It is important to note that although the “fat over lean” rule is a common practice, individual artists may adapt it to suit their specific technique or artistic vision. However, understanding this principle and its benefits is essential for any oil painting artist to make informed decisions and create works of art that will stand the test of time.

How to layer your painting using the fat-over-lean rule

Applying layers of paint using the ” fat over fat” rule involves a systematic approach to ensure the proper application of layers of fat a paint. Here’s a step-by-step guide to help you navigate the process:

• Start with a lean undercoat: Start your painting with a thin coat or undercoat. This initial coat should have less oil and a higher proportion of solvent. Dilute the oil paint with a solvent such as mineral spirits or turpentine to get a more fluid consistency. This thin layer creates the base and composition of your artwork;
• Gradually increase the oil content: As you progress to subsequent coats, increase the oil content of the paint mixture to create bold layers. Add drying oils, such as linseed oil or poppy seed oil, to the paint to make it richer and thicker. This gradual increase in oil content ensures that each coat is thicker than the previous one;
• Allow plenty of time to dry: It is very important to let each coat dry thoroughly before applying the next. This is especially important when going from lean to oily coats. Waiting until the previous coat has dried to the touch helps keep the overall painting stable and minimizes the risk of cracking or adhesion problems;
• Consider quick-drying products: If you prefer to work faster or have a busy schedule, you can include quick-drying mediums in your fat coats. Such mediums, such as alkyds, help speed up the drying process while maintaining the “fat over lean” principle. Follow the manufacturer’s instructions when using such media;
• Observe consistency when applying fat coats: As fat coats progress, try to maintain a constant oil content in these coats. Consistent oil content ensures even drying and helps maintain overall picture stability. Avoid using very fat mixes in one layer and much more liquid ones in the next;
• Adjust media and solvents: During the layering process, media and solvents may need to be adjusted to achieve the desired consistency and workability. Mediums can increase the oiliness of the paint and solvents can decrease it. Experiment and find the right balance for your particular painting technique and style.

Remember to always remember the “fat over lean” principle and its importance in maintaining the longevity and integrity of your work. This is a guide that should be adapted to your personal preference and technique. Understanding the materials you are working with and their properties is the key to successfully applying the fat-over-lean rule.

What happens if you don’t follow the fat-over-lean rule?

If you don’t follow the “fat over lean” rule in oil painting, it can lead to a number of problems that can affect the stability and longevity of your artwork. Here are some of the consequences that can occur if you don’t follow this rule:

• Adhesion problems: Neglecting the ” fat-over-lean” principle can lead to poor adhesion between layers of paint and support (canvas or panel). This can cause the top coats to eventually begin to peel, crack or peel off, causing your artwork to deteriorate;
• Cracking: Applying thick coats directly on thin coats without enough time to dry can lead to cracking. Underlying lean coats may dry faster and shrink in size, while fatty coats, which dry slower, remain flexible. This discrepancy in drying rate and flexibility can cause stress and eventually lead to cracking of the paint film;
• Drying problems: Failure to follow the ” fat-over-lean” rule can result in uneven drying of all coats. If fat coats are applied too early or lean coats are skipped, the layers underneath may not have time to dry properly. This can lead to solvent or moisture retention, causing potential problems such as blooming, yellowing, or even mold growth;
• Lack of flexibility: Without a gradual increase in oil content from thin to thick layers, the paint film may not have the necessary flexibility to adjust to the natural expansion and contraction that occurs with changes in temperature and humidity. This stiffness can stress the paint film, increasing the risk of cracking or delamination;
• Long-Term Stability: The ” fat-over-lean” rule is critical to maintaining the long-term stability of your artwork. By layering correctly, you create a structurally sound painting that can stand the test of time. Ignoring this rule can compromise the overall stability and integrity of your artwork, which can cause it to deteriorate or deteriorate over the years.

It is important to note that while the “fat-over-lean” rule is common practice, some artists may deliberately deviate from it to achieve certain effects or to experiment with alternative techniques. However, understanding the possible consequences and making informed decisions are very important for the longevity and preservation of your artwork.

Conclusion

By following the “fat-over-lean” rule, you can ensure that your oil paintings have a solid base, exhibit proper adhesion, remain flexible, and have every chance of remaining intact and visually appealing for years to come.