Lead Hardness Scale vs. Standard International Cartridge
Comparing 2 standards across 12 specifications. 12 key differences identified.
The Graphite Hardness Grading Scale (standardized under ISO 15184 and ASTM D3363) classifies pencil graphite from 9H (hardest, lightest grey, highest clay content) through HB (medium equilibrium) to 9B (softest, darkest black, highest graphite content). HB is the universal writing standard and the exact equivalent to the North American No. 2 pencil.
The Standard International Cartridge (also known as the European or Universal cartridge) is the dominant standardized fountain pen ink format, featuring a 2.4 mm nozzle opening sealed with a plastic sphere. Available in Short (38 mm / 0.85 ml) and Long (72 mm / 1.4 ml) sizes, it is used by dozens of European and American fountain pen manufacturers.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Hard Grade Range (9H to 2H)
|
9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H — high clay/polymer binder ratio, crisp hairline precision, zero smudging | — |
|
Medium Equilibrium Range (H, F, HB, B)
|
H (Hard), F (Fine point retention), HB (Hard Black — standard writing balance), B (Black) | — |
|
Soft Grade Range (2B to 9B)
|
2B, 3B, 4B, 5B, 6B, 7B, 8B, 9B — high graphite content, deep velvety blacks, artistic shading | — |
|
US No. 2 Pencil Equivalent
|
HB grade (mandatory for optical Scantron standardized bubble test optical scanners) | — |
|
US Numbering System Cross-Check
|
#1 = B | #2 = HB | #2.5 = F | #3 = H | #4 = 2H | — |
|
Origin
|
Developed by Joseph Hardtmuth of Koh-i-Noor in Vienna (1790s), who introduced the H/B alphanumeric system | — |
|
Short Cartridge Dimensions
|
— | 38.0 mm length × 7.0 mm diameter (approx. 0.80 to 0.85 ml ink capacity) |
|
Long Cartridge Dimensions
|
— | 72.0 mm length × 7.0 mm diameter (approx. 1.40 to 1.50 ml ink capacity) |
|
Bore / Nozzle Diameter
|
— | 2.4 ± 0.05 mm (friction-fits over the pen feed nipple) |
|
Internal Seal
|
— | Floating polystyrene bead / puncture disc pushed into cartridge body upon insertion |
|
Two-in-Barrel Tandem Storage
|
— | Most full-size pens store one active short cartridge plus one inverted spare short cartridge in the barrel |
|
Brand Compatibility
|
— | Kaweco, Pelikan, Montblanc, Faber-Castell, Visconti, Diplomat, Caran d'Ache, Jinhao, Waterman (long) |