Yes, artist oil paints can go bad, although properly sealed oil paints can theoretically last a very long time. The primary issues that cause oil paints to deteriorate include hardening within the tube, separation of oil and pigment, and potential mold or mildew growth on the painted canvas.
How Oil Paint Deteriorates
Here's a breakdown of the common ways oil paints can degrade:
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Hardening in the Tube: If the tube isn't sealed properly after use, the oil can react with air and begin to harden. This makes the paint unusable or difficult to work with.
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Oil Separation: Over time, the oil binder (usually linseed oil) can separate from the pigment. While this isn't necessarily "bad," it requires re-mixing the paint thoroughly before use. If the oil becomes rancid, that is a problem.
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Mold and Mildew: Under improper storage conditions (e.g., high humidity), mold or mildew can grow on the surface of dried oil paintings.
Factors Affecting Oil Paint Longevity
Several factors influence how long oil paints remain usable:
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Tube Closure: A tightly sealed tube is essential. Clean the threads of the tube and cap before closing to ensure a good seal.
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Storage Conditions: Store tubes of paint in a cool, dry place, avoiding extreme temperatures. Finished paintings should be stored in a climate-controlled environment to prevent mold and mildew.
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Pigment Type: Some pigments are more stable than others. Modern, high-quality pigments are generally more durable than older, less refined ones.
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Paint Quality: Artist-grade paints typically have higher pigment concentrations and better-quality binders, contributing to their longevity compared to student-grade paints.
Tips to Extend the Life of Oil Paints
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Proper Sealing: Squeeze out any air from the tube before recapping it. Consider using airtight containers or plastic wrap to further protect partially used tubes.
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Cleanliness: Keep your palette and painting area clean to prevent contamination.
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Storage: Store tubes and paintings in a stable environment, away from direct sunlight and extreme temperatures.
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Regular Inspection: Check your tubes and paintings periodically for signs of hardening, separation, or mold growth.
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Palette Knife Mixing: Use a palette knife to thoroughly mix separated paint before use. If the oil has become rancid, discard the paint.
In summary, while quality oil paints possess inherent durability, degradation can occur with improper handling and storage. Prevention is key to maximizing the lifespan of your paints and artwork.
