applying varnish to a painting with a wide brush

Understanding Painting Varnishes: Types, Benefits, and Application

August 2, 2023 Gavin Coates

Painting varnishes play a crucial role in protecting artworks and enhancing their appearance.

Varnish for painting is a protective coating that enhances colors, adds sheen (gloss, matte, or satin), and shields the surface from dirt and damage.

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This article aims to provide a comprehensive understanding of painting varnishes, their types, benefits, and proper application techniques.

I. What is a Painting Varnish? A painting varnish is a protective coating applied to the surface of a painting. It can intensify pigments' appearance through light refraction, a process known as "saturation." Varnishes can be clear or toned with pigments to balance aging artworks.

II. Types of Painting Varnishes:

Natural Varnishes: Traditional solutions of natural or synthetic resins in organic solvents that dry transparently. Examples include tree resins (mastic and dammar), fossil resins (copal), and insect excretions (shellac).
Synthetic Varnishes: Modern formulations providing various surface characteristics. They differ from natural varnishes but are commonly used by artists.

III. Importance of Varnishing:

Protection: Varnishes shield paintings from dust, dirt, and pollutants, making them easier to clean without damaging the paint layer.
Saturation: Varnishes intensify colors, especially in oil paintings, giving them a radiant finish.
Even Sheen: Varnishes can provide a consistent gloss, satin, or matte finish across the entire painting.

IV. Application of Varnishes:

Isolation Coat: Before applying varnish, artists should use an isolation coat (gloss medium) to provide an even surface and prevent varnish from directly contacting the paint layer.
Varnish Selection: Artists can choose from water-based varnishes (polymer) or solvent-based varnishes (MSA). Each type has its pros and cons in terms of application and cleanup.
Varnishing Technique: Use a flat, wide, soft brush to apply varnish smoothly in one direction. Avoid going over already coated areas and allow the painting to dry completely between coats.

V. Varnish Removal and Replacement:

Natural Varnishes: Over time, natural varnishes may darken and require replacement by a skilled paintings conservator.
Synthetic Varnishes: Synthetic varnishes may offer greater longevity but have different properties than natural varnishes.

VI. To Varnish or Not to Varnish:

Matte vs. Gloss: Artists should consider their preference for the appearance of the painting—whether a glossy, matte, or satin finish is desired.
Acrylic Paintings: Applying varnish to acrylic paintings requires careful consideration due to the risk of damaging the paint layer during removal.

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Understanding painting varnishes is essential for preserving and enhancing artworks. Artists must choose the right type of varnish, apply it correctly, and weigh the aesthetic and protective considerations. Seeking professional advice from paintings conservators can be helpful in ensuring proper varnishing and preservation techniques.