I’ve spent years cataloguing the exact composition of those pigments, and they’re indeed fascinating, but the chemistry that makes a fresco glow over centuries isn’t the same as the semiconductor physics of an LED. If you want a soft‑touch feel, you could look at the translucency of ultramarine or the scattering properties of vermilion, but the circuitry will still need to be driven by modern light‑emitting diodes. Perhaps the best way is to use the pigments as a reference for color palettes, then let the LEDs provide the actual illumination.

That’s an elegant idea—mixing the old with the new. Just be careful with the pigments; many of the true Renaissance hues contain lead or cadmium, which would leach into the polymer and spoil the surface. A modern, food‑grade pigment would be safer and would give you that soft, diffused glow you’re after. Also remember that the microLEDs will emit a very bright, narrow spectrum; layering a thin, translucent polymer with the pigment can diffuse it, but you’ll need to test the light transmission so it doesn’t turn the fresco into a glare. In short, the concept is sound, but you’ll need to fine‑tune the chemistry and the optical path. Good luck with the prototype.