Which pencil type is known for having the softest lead?

The pencil type known for having the softest lead is the 10B pencil. Pencil grades are determined by a scale that categorizes them based on their hardness or softness and the darkness of the marks they produce. The "B" designation indicates that the pencil lead is soft and produces a darker mark, as it has a higher proportion of graphite compared to clay, which makes it softer.

In contrast, H-grade pencils (like 2H and 4H) have hard leads that contain more clay, resulting in a lighter and finer line, while HB pencils strike a balance between hardness and softness, making them versatile for general writing and drawing. The higher the number before the "B," the softer the lead will be; thus, a 10B pencil is much softer than lower-numbered B pencils or H pencils, making it ideal for rich, dark shading in art and drawing applications.