An HB pencil is designed for writing numbers (e.g. accountants may use them or draftsmen when drawing architecture etc.). An HB is a hard led and cannot produce lovely soft lines, tonal values or sensitivity (e.g. thickness and thinness to a line). An HB is likely to cut the silk if you are drawing directly onto the silk, they are so hard. A 2B to a 6B are the ones to be used in drawing. I mainly use a 2B and a 6B – I only used the latter in the framed drawing of the lady that you saw in Module 9 (nine).