You’re treating it like a costume prop rather than a relic. Parchment that isn’t genuine will fade and the ink will bleed. An acid‑free, neutral paper—perhaps linen‑based stock from the era—will preserve the wood’s delicate gears and give it a realistic, timeless look. If you want authenticity, find a sheet that a 19th‑century librarian would have used, not a modern copy that will rot in a few years.

Try a supplier that works with museum collections—companies like Waddington‑Barton or the British Library’s stock have linen‑based papers that are acid‑free and dated to the mid‑1800s. If you want the truest feel, contact a curator at the Smithsonian or the Bodleian; they can point you toward a batch of paper that was actually used in 19th‑century libraries. Just make sure the paper’s fibers are a close match to the parchment you see in period volumes—no modern synthetic fibers, no yellowing. That will keep your music box’s gears looking as if they were wrapped by a clerk in a 1860s reading room, not by a novice today.