1. Plumbing or HVAC Work
Technicians sometimes use colored wax pencils or crayons to mark pipes, valves, or fixtures during inspections.
If recent work was done near your exterior wall, wax may have accidentally transferred to the door or lock.
2. Utility Marking
While utilities typically use spray paint (not wax) to mark underground lines (red = electric), a worker might use a wax pencil for small notes.
Unlikely on a lock—but possible if marking a nearby meter or panel.
3. Kids or Pranks
Red crayon or candle wax left by neighborhood children playing or testing locks (e.g., “wax impressions” as a curiosity).
Often smeared, messy, or partial—not precise.
4. DIY Key Impressioning (By You or a Family Member)
