Reworking an old painting involves careful consideration and techniques to preserve the original artwork while making necessary repairs or changes. Here's a high-level summary:
1. **Seek professional help**: If the painting is damaged or requires significant repairs, it's best to consult a Conservator who can perform tear mending, inlays, and other specialized treatments (Source ID: 1).
2. **Oiling out**: When repainting is not possible, applying a small amount of drying oil to a specific area can help even out the sheen, but this should be done with caution and only as needed (Source ID: 5).
3. **Varnish removal**: Removing varnish from a painting requires a delicate process, using a solvent-dampened cloth and gentle patting to avoid damaging the paint layers below (Source ID: 7, 8).
4. **Isolation coats and testing**: Artists may use isolation coats with various binders to test for color change and durability, and some components that cause yellowing can potentially be removed through swabbing or sponging (Source ID: 6).
It's essential to approach reworking an old painting with care and caution to preserve the artwork's integrity. If unsure, it's best to consult a professional Conservator or contact Golden Artist Colors for guidance (Source ID: 1, 3).