Lead Hardness Scale vs. Fountain Pen Cartridges
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.
Proprietary Fountain Pen Cartridges are brand-exclusive ink formats engineered with unique nozzle diameters and collar locking geometries that are incompatible with Standard International pens. Key proprietary systems include Pilot/Namiki (wide 5.5 mm bore), Lamy T10 (stepped collar), Sailor (flared collar), and Platinum (metal ball seal).
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 | — |
|
Pilot / Namiki Cartridge
|
— | Length: 59.0 mm | Wide 5.5 mm bore | Capacity: ~0.90 ml (IC-50 / IC-100 / Parallel) |
|
Lamy T10 Cartridge
|
— | Length: 68.0 mm | Stepped friction collar | Capacity: ~1.15 ml (Lamy Safari, 2000, Studio) |
|
Sailor Proprietary Cartridge
|
— | Length: 48.0 mm | Flared ribbed collar | Capacity: ~1.00 ml (Sailor 1911, Pro Gear) |
|
Platinum Proprietary Cartridge
|
— | Length: 65.0 mm | Metal stainless steel sealing ball | Capacity: ~1.20 ml (Century #3776, Preppy) |
|
Parker Quink Cartridge
|
— | Length: 76.0 mm | Stepped friction plug with reserve tank | Capacity: ~1.20 ml |
|
Cross Cartridge
|
— | Length: 38.0 mm | Narrow tapered mouth (Classic Century vs Townsend / Peerless) |