Instead of bleach, try OxiClean.
You'll still want to cover stamps/dots/etc. But it won't eat into Vulcanite like bleach will, so it requires less sanding/buffing.
After 4 hours or so, bleach will loosen oxidation. But after 12 (or 24, if you forget about it), it'll eat into the Vulcanite, making it rough and much harder to finish.
With OxiClean, you can safely soak overnight without any worry of this.