I noticed that in the following picture there are at least 3 kinds of charcoal pencils:
- Wooden charcoal pencil with just the word soft written on it.
- Paper wrapped charcoal pencil with 600-H written on it.
White charcoal pencil with 558 written on it.
- Are there more varieties of charcoal pencils? What are their properties that make them different from each other?
- How does paper wrapping effect the charcoal pencil as compared to wood?
- Why would there be specific number written on paper wrapped pencil but not on wooden one?