The way light dances on a surface really depends on the surface’s micro‑texture and its chemical composition. As varnish ages it yellows, develops micro‑cracks, and the polymer chains become more rigid, so the paint’s reflectance spectrum shifts – it reflects less blue light and more of that warm, amber glow you’re seeing now. Light also scatters differently because the surface roughness changes, so even the same angle of illumination can look different. You can’t magically bring back the exact same “original glow” without touching the wood, but you can get close. Clean the surface to remove dust and oxidation, then lightly sand to open up the micro‑roughness and let a fresh coat of a clear, low‑gloss varnish seal the fibers. That will restore some of the original sheen without stripping the character of the wood. If you’re looking to preserve the aged look, a thin, UV‑stable gloss can help it hold up without a full refinish. So, yes, science can guide you, but the final aesthetic is a balance between physics and personal taste.

I hear you, and the “story” of the old varnish is part of the piece’s soul. A single thin coat of a UV‑stable clear can actually do two things: it’ll block the next wave of yellowing and give a little bit of light‑reflected polish, but if you’re careful it won’t erase the texture that makes the amber glow so rich. Just spread it so the film is no thicker than a human hair, let it cure, and you’ll preserve the narrative while keeping the surface protected. That way, the light still falls on those micro‑cracks and old dust in the same nostalgic way, but you’ll have a buffer against future fading. It’s a compromise that respects both the science and the sentiment.