The key to preserving egg tempera paint, both during and after use, lies in preventing spoilage and ensuring proper application and storage. Here's how:
Preventing Spoilage During Preparation
- Add a Preservative: Incorporating a small amount of white vinegar is a crucial step. Specifically, add a drop or two of white vinegar to the beaten egg yolk. This helps inhibit bacterial growth and extends the paint's usability.
- Proper Mixing: Gradually add your chosen pigment powder to the egg yolk mixture, ensuring thorough blending to create a smooth, consistent paint. This prevents clumps that can harbor bacteria.
Best Practices During Painting
- Prepare Only What You Need: Mix only the amount of egg tempera paint you anticipate using in a single session. This minimizes the amount of paint that could potentially spoil.
- Use Clean Tools: Always use clean brushes, palettes, and containers to prevent contamination of the paint.
Storage Strategies for Unused Paint
- Refrigeration: If you have leftover egg tempera paint, store it in an airtight container in the refrigerator. Even with vinegar, egg tempera is perishable and will spoil if left at room temperature for extended periods.
- Limited Storage Time: Even refrigerated, egg tempera paint has a limited shelf life. Typically, it will only last for a few days (2-3 days) before it begins to spoil. Watch for signs of spoilage like a foul odor or change in consistency.
- Airtight Containers: Ensure that containers used for storage are truly airtight to prevent the paint from drying out or absorbing moisture.
Preserving the Painted Surface
- Sealing (Optional): While egg tempera is durable, some artists choose to seal finished paintings to protect them from moisture and dirt. This is typically done with a very thin layer of varnish specifically designed for egg tempera, applied after the paint is completely dry (which can take several months). Research appropriate varnishes carefully.
- Controlled Environment: Store completed egg tempera paintings in a stable environment, away from direct sunlight, extreme temperature fluctuations, and high humidity.
