A Comprehensive Guide to Painting Techniques and Materials

Posted on Sep 4, 2024 in Geology

Painting

Painting, the mother of art, encompasses two-dimensional techniques using various materials. It involves a support and pictorial material, including:

Pictorial Materials

  • Colorant: This refers to the pigments used.
  • Binder: This substance (e.g., egg, oil) determines the painting process and holds the pigments together.
  • Diluent: This thins the paint for easier application.

Exception: Fresco painting is defined by its support and application rather than the binder.

Once a painting is complete, it’s typically covered with varnish for preservation.

Elements of Pictorial Matter

  • Dyes: These colorants must meet specific criteria:
    • Compatibility and Permanence: Pigments should be compatible with the chosen process, permanent, and resistant to fading caused by atmospheric agents or chemical reactions with the support and preparation.
    • Hiding Power: This refers to the pigment’s ability to prevent light penetration, influenced by the refractive properties of its particles and the binder.
    • Absorption Power: This relates to the pigment’s ability to absorb light.

Binders

Binders play a crucial role in painting:

  1. Functions:
    • Bind pigment particles together.
    • Harden and adhere to the support.
    • Protect the pigment.
    • Influence the visual quality of the pigment, ensuring its longevity.
  2. Types:
  • Animal-Based Aqueous Binders:
    • Glue: Obtained by boiling animal skin, cartilage, or bones (typically sheep or cow) in a water bath.
    • Egg Yolk: Used for its binding and emulsifying properties.
    • Casein: A milk protein with binding capabilities.
  • Fatty Binders:
    • Linseed Oil: Highly regarded for its fast drying time and glycerin content, which aids in hardening.
    • Other Oils: Rapeseed, walnut, and sunflower oils can also be used (olive oil is less suitable due to its slow drying time).
    • Waxes: Both animal and plant-based waxes are employed, often in mixed techniques.

Solvents/Diluents

These substances soften or dilute pigments and must be compatible with the chosen binder. Each binder requires a specific solvent.

Varnishes

Varnishes, initially made from egg whites, serve as a protective layer against environmental damage. The ancient Greeks used wax and later resin-based oils. Varnishes need periodic renewal (approximately every 50 years) due to potential yellowing and dirt accumulation.

Types of varnishes include:

  • Dilutable varnishes
  • Resin acid varnishes
  • Artificial resin varnishes
  • Animal origin varnishes

Supports

Wall

Walls have served as a natural support for painting since prehistoric cave paintings. Various painting techniques, including tempera, oil, and acrylics, can be applied to walls.

Note: Mural painting is not synonymous with fresco. Fresco is a specific type of mural painting.

Wall Preparation

  • Roman Times: Walls were prepared with two or three layers of sand and lime, as described by Vitruvius and Pliny. This technique is evident in the semifresco murals of Pompeii.
  • Medieval Period: Murals were often painted on dry plaster (a secco) or using a fresco-secco technique. Pigments were fixed with binders like lime, tempera, or oil.
  • Contemporary Practices: Silicate paint and sgraffito are modern techniques used for wall paintings.

Types of Wall Painting

  1. Fresco: This technique involves painting on wet plaster, allowing the pigments to bind chemically with the lime as it dries. This process, known as carbonation, creates a durable, almost marble-like surface. Fresco requires careful control of drying conditions to ensure even color absorption. Pigments are typically mineral-based, ground in water, and applied in multiple layers to achieve desired intensity. The wall surface is usually stone or brick, and the plaster composition has varied throughout history. The intonaco, a final layer of fine plaster, receives the pigment.
  2. A Secco: This method involves painting on dry plaster using binders like lime, tempera, or oil to fix the pigments.
  3. Mixed Technique: This approach combines elements of both fresco and a secco.

Fresco Restoration

Frescoes are ideally preserved in their original location. Deterioration often stems from moisture and salt crystallization, which can be mitigated through drainage solutions. Cleaning typically involves gentle methods like using water and ammonia.

Restoration techniques include:

  • Stucco: Lifting and reattaching the intonaco and plaster.
  • Strappo: Removing only the paint layer when other methods are unsuitable.
  • Amassello (Sawing): A complex process involving cutting out a section of the wall.

Wood

Wood panels of varying thicknesses and dimensions have been used as painting supports. Different assembly methods, such as butt joints, dowels, and dovetails, are employed to create these panels. Reinforcement is often added to the back using slats or bars.

Fabric (Canvas)

Canvas gained prominence as a painting support in the 16th century with the rise of oil painting. Its advantages include portability, flexibility in size, and ease of preparation. Early canvases were primarily made from plant fibers like hemp, flax, jute, and cotton, while silk was also used.

Canvas consists of interwoven threads: the warp (lengthwise threads) and the weft (crosswise threads). The fabric is stretched taut on a frame, typically made of wood and assembled without glue. Canvas, being cellulose-based, is susceptible to damage from fungi, bacteria, acids, and loss of elasticity. These factors should be considered when selecting and preparing a canvas.

Understanding these fundamental aspects of painting materials and techniques provides a foundation for appreciating the artistry and craftsmanship involved in this art form.