# Refills, Leads & Ink Cartridges

A refill is bought for a pen or pencil the buyer already owns, so fit matters more than taste. Many ballpoint refills share the G2 format, and many fountain pens take standard international cartridges. Among refills that fit, line width or lead grade and colour decide, and grades and point labels differ by brand.

## How it works

Every refill is the part of a writing instrument that runs out, so it has to match the holder exactly. Ballpoint refills carry a thick oil-based paste that a small ball rolls onto paper. It dries on paper almost at once but does not dry out easily in the refill. Gel and rollerball refills use water-based ink on the same kind of ball. They write more smoothly and darker, but use ink faster and can dry out in the tip. Fountain pens take thin water-based ink by capillary action through a nib. It comes in cartridges, or in bottles drawn up by a converter, and most is dye, which does not resist water once dry. Pencil leads are graphite bound with polymer, sold by diameter and by an H-to-B hardness grade. A refill that does not fit is useless, whatever its ink, so format comes before chemistry. [1] [2] [3] [5] [13] [24] [25] [23]

| Family | What it is | Suits |
|---|---|---|
| Ballpoint paste | Thick oil-based ink that dries almost at once and rarely smears. Hybrid low-viscosity pastes (Jetstream, Acroball) sit between ballpoint and gel. | Everyday writing, left-handers, pens carried uncapped. |
| Gel ink | Pigment suspended in a water-based gel; opaque, vivid and often water-resistant once dry. | Smooth dark writing, colours, signing documents that must resist washing. |
| Rollerball liquid ink | Thin water-based dye ink in a ball tip; the smoothest line, but it needs a cap. Some rollerballs take fountain pen cartridges. | Writers who want fountain-pen flow without a nib. |
| Fountain pen ink | Thin water-based ink fed through a nib from a cartridge, a converter or a piston; mostly dye, some pigment or iron gall. | Fountain pen owners; colour choice and cost per millilitre matter. |
| Pencil lead | Graphite and polymer sticks in a fixed diameter and an H-to-B grade, for mechanical pencils and leadholders. | Writing, drafting and sketching where marks must erase. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Writing system
    pencil lead : ask Lead diameter, Lead grade : skip Pen refill format, Point size, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry, Fraud-resistant, documentary ink, Water-resistant once dry
    fountain pen ink : ask Cartridge, converter or bottle, Ink or lead colour, Water-resistant once dry : skip Pen refill format, Point size, Lead diameter, Lead grade
    ballpoint / gel : ask Point size, Ink or lead colour : skip Lead diameter, Lead grade, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry
    rollerball : ask Point size, Ink or lead colour : skip Lead diameter, Lead grade
    marker ink : ask Ink or lead colour : skip Lead diameter, Lead grade, Pen refill format, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry
  section 2 · Pen brand, line or format it fits
    Which pen is it for, or which refill does it replace?
  section 3 · Point size
    Extra fine, fine, medium, or broad line?
  section 4 · Ink or lead colour
    Black, blue, or another colour?
```

1. **Writing system.** Ballpoint, gel, fountain pen, or pencil lead?
   The writing system splits the catalog into sets sharing few facets: leads have diameter and grade, fountain ink has fill form and cartridge fit, pen refills have format and point size. Rollerball and marker answers keep their own values.
   If pencil lead: ask Lead diameter, Lead grade; skip Pen refill format, Point size, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry, Fraud-resistant, documentary ink, Water-resistant once dry.
   If fountain pen ink: ask Cartridge, converter or bottle, Ink or lead colour, Water-resistant once dry; skip Pen refill format, Point size, Lead diameter, Lead grade.
   If ballpoint or gel: ask Point size, Ink or lead colour; skip Lead diameter, Lead grade, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry.
   If rollerball: ask Point size, Ink or lead colour; skip Lead diameter, Lead grade.
   If marker ink: ask Ink or lead colour; skip Lead diameter, Lead grade, Pen refill format, Fountain cartridge fit, Cartridge, converter or bottle, Fountain ink chemistry.
   Skip if already known: a query naming a refill type, such as 'gel refill' or '0.5 mm lead', a pen or pencil model already named.

2. **Pen brand, line or format it fits.** Which pen is it for, or which refill does it replace?
   Fit is the hard gate. The pen brand or line, or the old refill's name, maps to a refill format, cartridge type or lead diameter through brand charts, so one answer removes refills that will not fit.
   Skip if already known: a pen or pencil model in the query or in memory.

3. **Point size.** Extra fine, fine, medium, or broad line?
   Within one format, point size is the main remaining choice. Most specialist titles state a label; mm-only listings are ranked by ball size. It splits pen refills into three or four groups.
   Skip if already known: a point size in the query, such as 0.5 mm or 'medium'.

4. **Ink or lead colour.** Black, blue, or another colour?
   Colour separates otherwise identical refills that fit: Goldspot titles state it and its buying advice says to choose it. For bottled fountain ink it is the main choice.
   Skip if already known: a colour in the query, such as 'blue-black' or 'red refill'.

## What to surface

### Writing system

Which kind of instrument the refill feeds: ballpoint, gel, rollerball, fountain pen, mechanical pencil or marker. The system decides which other facets exist at all. A gel refill and a ballpoint refill can share a format, but their inks behave differently: ballpoint paste resists drying out and smearing, gel and rollerball ink write smoother and darker and run dry sooner. Fountain ink and pencil lead have their own fit rules and nothing else in common. [1] [13] [10] [14] [24]

Values: ballpoint, gel, rollerball, fountain pen ink, pencil lead, marker ink.
Question to ask: Ballpoint, gel, fountain pen, or pencil lead?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Ballpoint Pen Refill', 'Gel Ink Refill', 'Rollerball Refill', 'Fountain Pen Ink Cartridges', 'Lead Refill'. Exclude printer ink and toner titles; they belong to printer accessories.
Mixed names need a rule: classify by the ink named, so 'Gel Ballpoint Refill' and 'gel rollerball' are gel.

### Point size

How fine a line the refill writes, labelled either as a ball diameter in mm or as extra fine, fine, medium or broad. It is the main choice left once the format fits. Labels are not on one basis: some makers attach F, M and B to the ball (Wikipedia puts a 0.7 mm ball at fine; Schmidt labels 0.8 and 1.0 mm balls M), others to the line written (Goldspot). A ball's diameter does not equal its line width, so a 0.5 mm gel ball and a Western fine ballpoint are not the same line. [1] [12] [10] [2]

Values: extra fine, fine, medium, broad.
Question to ask: Extra fine, fine, medium, or broad line?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: In the title: 'Fine Point', 'Medium Point', or a ball size such as 0.38, 0.5 or 0.7 mm.
Use the listing's own word (EF, F, M, B) and keep any mm. For mm-only listings, match a label answer by ranking within the format, smaller balls for finer answers. Only 1.0 mm as medium has two sources (Wikipedia, Schmidt); use other mm points to rank, not to exclude.
Chart: Line-width scale.

### Ink or lead colour

The colour the refill writes in, such as black, blue, blue-black or a named fountain ink shade. Once a refill fits, colour is what separates otherwise identical SKUs, and Goldspot's buying advice says to match colour along with point size. For bottled fountain ink colour is the main choice, and shades carry the maker's own names, so they need grouping into colour families. [10] [25] [14]

Values: black, blue, blue-black, red, green, other colour.
Question to ask: Black, blue, or another colour?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: In the title after 'in': 'Refill in Blue/Black', 'Lead Refill in Blue', 'Bottled Ink in Souboku (Deep Blue Pigmented)'. Graphite leads state none.
Pen refill colours are plain words. Named fountain ink shades ('Fox Red', 'Zhivago') map to a colour family from the name or the maker's swatch.
Chart: Colour swatch grid.

### Pen brand, line or format it fits

The pen or pencil brand, line or refill format the listing says the refill fits, kept as the listing states it. A refill that does not fit is worthless. Specialist retailers tell buyers to identify the format first and always match it to the pen, because similar-looking refills differ in length, diameter and tip. Listings mostly name a pen brand, line or format ('Parker Style', 'Lamy'), not a model, so the buyer's answer is matched at that level. [10] [14] [11]

Question to ask: Which pen is it for, or which refill does it replace?

Used as: top-level split, filter. Data: on the listing, backfill cost low. Look for it as: In the title, e.g. 'Parker Style', 'Lamy', 'Cross', 'Retro 51 Tornado Lead Refill'. The add-on keeps it verbatim as compatibility_raw.
When the title names only a refill code, map the code to pen brands with the brand's compatibility chart. A buyer who knows only the old refill's name is matched through the same chart.

### Cartridge, converter or bottle

Whether fountain pen ink comes in sealed cartridges, as a converter that draws ink from a bottle, or as bottled ink. Cartridges are the cleanest swap. Bottled ink costs less for the same amount, offers far more colours and properties, but needs a converter or a piston pen. A converter must match the pen's fitting just as a cartridge does, and some compact pens cannot take one at all. [3] [11]

Values: cartridge, converter, bottled ink.
Question to ask: Cartridges, or bottled ink with a converter?

Used as: filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: In the title: 'Ink Cartridges', 'Converter', 'Bottled Ink' with a volume in ml.
That the form is in the title is untested: no fountain-ink listing page was read for this field, only a compatibility chart and an archived Nibs page.

### Fraud-resistant, documentary ink

Whether the dried ink resists the solvents used to wash writing off cheques, or carries an ISO documentary-use (DOC) grade. ISO sets documentary-use (DOC) grades for ballpoint, rollerball and gel refills; what DOC tests was not read, so treat it as a quality claim, not proof against washing. Fraud-resistant gel resists acetone and check washing, and a sheriff's office advised gel over ballpoint for cheques. A yes keeps fraud-resistant gel, DOC-graded refills and permanent pigment or iron gall inks; ballpoint without a DOC grade and dye inks drop. [17] [21] [22] [1] [2] [18] [25]

Question to ask: For cheques or documents that must resist tampering?

Used as: filter. Data: needs research, backfill cost medium. Look for it as: Look for 'fraud resistant', 'Super Ink', 'archival', 'document', 'permanent', 'ISO 12757-2', 'ISO 14145-2' or 'ISO 27668-2' in bullets or on the maker's page.
Keyword pass on bullets first; confirm on maker pages for the top N gel and ballpoint refills only.

### Water-resistant once dry

Whether the dried ink stays on the paper when it gets wet. Addresses, outdoor notes and journals need ink that survives a spill, which is a different need from fraud resistance. Many gel inks resist water once dry. Standard dye fountain inks do not; pigment and iron gall fountain inks do, and Goldspot sells them as a separate group with a warning that results vary by paper. [2] [25] [3] [15]

Question to ask: Must it survive water once dry?

Used as: filter. Data: needs research, backfill cost medium. Look for it as: Look for 'water resistant', 'waterproof', 'pigment', 'Carbon' or 'iron gall' in the title or bullets.
Keyword pass on titles and bullets first; confirm on maker pages for the top N gel and fountain inks only. Do not infer 'no' from a missing keyword.

### Lead diameter

The nominal thickness of a pencil lead in millimetres, which must match the pencil. A mechanical pencil takes one diameter only, so this is a hard filter. Thin leads draw finer lines but break more; Wikipedia names 0.5 and 0.7 mm as the writing sizes that balance precision and strength; 2 mm and up go in leadholders for drafting and art. [5] [14]

Range: 0.5 and 0.7 mm in writing pencils; 2 to 5.6 mm in leadholders.
Question to ask: 0.5 mm, 0.7 mm, or another lead size?

Used as: filter. Data: on the listing, backfill cost none. Look for it as: In the title after the grade, e.g. 'Lead Refill - HB - 0.5mm'.

### Lead grade

Where the lead sits on the H (hard, light) to B (soft, black) scale, with HB in the middle. Softer B grades write darker and smoother but smudge and wear faster; harder H grades stay sharp and light. Lead titles usually state the grade, but there is no common standard, so one brand's HB is not another's; pencils.com says Japanese HB is generally softer and darker than European HB. Colour leads carry no grade. [6] [7] [14]

Values: 3H or harder, 2H, H, F, HB, B, 2B, 3B or softer, colour (no grade).
Question to ask: Darker and smoother, or lighter and crisper?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title, e.g. 'Lead Refill - 2B - 0.5mm'. Colour leads carry a colour instead.
Answer mapping: darker means B or softer, lighter means H or harder, unsure means HB. Some lead titles carry no grade (Goldspot's colour leads and some brand leads); leave those empty or mark colour.
Chart: Pencil grade scale.

### Fountain cartridge fit

Whether a fountain pen cartridge or converter is the standard international type, in short or long, or one brand's proprietary fitting; bottled ink has no fit. Standard international cartridges from any maker fit most pens that take them, which opens hundreds of inks. Pilot, Platinum, Sailor, Parker, Lamy and others use proprietary cartridges, with exceptions: Aurora and Parker interchange, Lamy unofficially fits Parker, and Platinum takes international with an adaptor. Some compact pens take only short cartridges, and some Waterman models block short ones. Cartridge rollerballs use the same fittings. [3] [15] [11] [23]

Values: standard international, short, standard international, long, brand proprietary.

Used as: filter. Data: derived from listing fields, backfill cost medium. Look for it as: Often in the title or first bullet ('international', 'standard', 'for Pilot pens'); the pen side is in brand charts such as Goldspot's.
Not asked: resolved from the pen_model answer. Applies only to cartridges and converters. One chart lookup per pen brand covers most of the catalog; brands with several fittings (Cross, Lamy, Pilot, Namiki) need the model.

### Pen refill format

The physical refill standard a ballpoint, gel or rollerball refill is built to, which decides which pens it fits. G2, also sold as Parker-style, is the format Schmidt calls universal and fits many brands' pens; D1 is the mini format for slim and multi-pens; Cross, Lamy M16 and Fisher pressurised refills are their own. Pilot's G2 gel pen is a different thing from the G2 format. Rollerball refills with the same tip come in different lengths. Cartridge rollerballs take fountain pen cartridges instead of a refill. [9] [10] [1] [23]

Values: Parker-style G2, D1 mini, Cross-style, Lamy M16, Fisher pressurised, cartridge rollerball, brand-specific other.

Used as: filter, shown on the card. Data: derived from listing fields, backfill cost low. Look for it as: Specialist retailers put it in the title ('Parker Style', 'D-1 Mini'); elsewhere derive it from compatibility_raw plus the refill code, or the maker's page.
Not asked: resolved from the pen_model answer through brand charts. Map refill codes to formats once per brand; that the code set is small and stable is our assumption, not verified, and formats cross over (Fisher refills with a Parker-style adapter).

### Pen maker's own or compatible

Whether the refill is sold by the pen's maker or by another company making the same format. Unlike printer cartridges, compatible pen refills are a normal upgrade path: Schmidt says nearly all major pen brands use its refills, and specialist retailers sell Schmidt and Monteverde refills for Parker, Cross and other pens. Fountain pen makers disagree and discourage cheap international cartridges, citing uneven ink. [9] [10] [3]

Values: pen maker's own, compatible.

Used as: shown on the card. Data: derived from listing fields, backfill cost low. Look for it as: Compare the refill maker with the pen brand named. Goldspot puts the pen brand first for compatibles ('Lamy Ballpoint Pen Refill by Monteverde'), so the brand field alone misreads them as the pen maker's own.

### Fountain ink chemistry

Whether a fountain pen ink colours with dissolved dye, suspended pigment, or iron gall compounds that darken on paper. Chemistry trades permanence against upkeep. Standard dye inks do not resist water. Pigment inks made for fountain pens, such as Platinum Carbon and Sailor's pigment blacks, resist water but need regular cleaning. Modern iron gall inks bond to paper but can corrode a pen if left in long. Inks not made for fountain pens, such as India ink, clog them. [3] [4] [16] [15] [25]

Values: dye, pigment, iron gall.

Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Named in the product name when not dye ('Carbon', 'Pigment', 'Iron Gall', 'Registrar's'); dye is the unstated default.
Not asked: shown as an annotation and read from product-name keywords and the maker's page. Default to dye, but do not infer water_resistant or document_proof 'no' from that default.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Fountain ink cost per millilitre (currency per ml) | `price / (pack_count x ml_per_unit), where ml_per_unit is the bottle volume or one cartridge's capacity` | Bottled ink usually costs less than the same amount in cartridges. Bottles state ml on the label; cartridge capacity is rarely listed, so compute it only where the maker publishes it. Undefined for converters, which hold no ink as sold.  |

## What you give up

- Gel and rollerball ink glides and looks darker, but a rollerball uses far more ink than a ballpoint and needs a cap to stop drying out. Ballpoint paste lasts longer and dries at once. [13] [1] Board branch: "See more long-lasting ballpoint refills".
- Pigment and iron gall fountain inks survive water, but pigment can clog a feed and iron gall can corrode if left in. Standard dye inks are carefree but do not resist water. [16] [3] [4] [25] Board branch: "See more easy-cleaning dye inks".
- Standard international cartridges open the widest ink choice; pen makers argue their own cartridges suit their nibs better and cheap cartridges can skip or feather. [3] [11] Board branch: "See more inks for international-cartridge pens".
- Thinner leads draw finer lines but break more; Wikipedia puts 0.5 and 0.7 mm at the balance point for writing. [5]

## How to draw it

**Pencil grade scale** (scale, shows Lead grade). One H-to-B axis with HB in the middle, spanning only the grades refill leads come in, so a buyer sees how far a grade is from their usual. Colour leads sit off the axis. Used today by Pencil makers' grading charts; Wikipedia shows a 9H to 9B chart for wood pencils, wider than refill leads.. [6] [7]

**Line-width scale** (range, shows Point size). A millimetre axis with ball sizes and F, M, B line labels drawn separately, so a 0.5 mm gel and a fine ballpoint stop looking equal. This is a proposal, nobody draws it this way yet. [1] [12]

**Compatibility matrix** (other, shows Pen brand, line or format it fits, Pen refill format, Fountain cartridge fit). Pen brands down the side, refill or cartridge types across, a mark where they fit; the shared formats show up as full columns, and adaptor fits get their own mark. Used today by Specialist retailers' cartridge and converter charts, such as Goldspot's.. [11]

**Colour swatch grid** (swatch grid, shows Ink or lead colour). Swatches grouped by colour family, so named fountain ink shades and the same refill in several colours are compared by eye. Used today by Retailers' shop-by-colour pages, such as Goldspot's 'Inks by Color'.. [25]

## Words you will meet

- **Refill format**. The size and shape standard a pen refill is made to, which decides which pens it fits.
- **G2 (Parker-style)**. The large-capacity ballpoint refill size that fits many brands' pens, first made popular by Parker.
- **D1**. A short, thin refill size used in slim pens and multi-colour pens.
- **Standard international cartridge**. A fountain pen ink cartridge in a shared short or long size that fits many brands' pens.
- **Proprietary cartridge**. A cartridge shaped to fit only one brand's fountain pens.
- **Converter**. A refillable piston or squeeze reservoir that fits where a cartridge goes, so the pen can fill from a bottle.
- **Pigment ink**. Ink coloured by tiny solid particles that sit on the paper and resist water.
- **Iron gall ink**. Ink whose iron compounds darken and bind to paper as it dries, making it permanent but acidic.
- **Documentary (DOC) ink**. A refill grade under an ISO standard that sets minimum quality for writing on official documents.
- **Check washing**. A fraud in which thieves dissolve the ink on a stolen cheque and rewrite it.
- **HB scale**. The pencil grading scale where H means harder and lighter, B means softer and blacker.
- **Leadholder**. A pencil that grips one thick lead in jaws, used for drafting and art.
- **Hybrid ink**. Ballpoint paste made thinner than usual so it writes smoother but still dries fast.
- **Point size**. How fine a line a refill makes, stated as a ball size or as fine, medium or broad.
- **Cartridge rollerball**. A rollerball pen that draws ink from a fountain pen cartridge instead of a sealed refill.
- **Blue-black**. An ink colour between dark blue and black, common in fountain pen inks.

## Where we made a call

- Lead grades are comparable within one brand only; HB from a Japanese maker is generally softer and darker than European HB. (confidence medium). One source: pencils.com. Wikipedia's 'no common standard' sentence cites pencils.com, so it is not independent. [7] [6]
- Point sizes do not compare across labels: ball diameters and F, M, B line widths are different measures. (confidence medium). Sources disagree. Wikipedia puts a 0.7 mm ball at fine and 1.0 mm at medium; Schmidt labels 0.8 and 1.0 mm balls M; Goldspot defines F, M, B by line width. We keep the bases separate and rank mm-only listings. [1] [9] [12]
- The printer-cartridge rule that third-party refills are a trap does not carry over to pen refills, where fit decides. (confidence medium). Sources disagree. Schmidt says nearly all major brands use its refills, a self-interested claim; retailers sell compatibles openly. Fountain pen makers discourage cheap international cartridges. We side with fit first, maker's ink as an annotation. [9] [10] [3]
- CPSC does not enforce ASTM D-4236 labelling on single-colour pens and pencils not marketed for art; multi-colour packs are likely art materials. (confidence medium). Single source: 16 CFR 1500.14(b)(8)(iv)(A)(1), an enforcement policy, not a scope exclusion. It names pens and pencils, not refills, so multi-colour lead packs may need the D-4236 line. CPSC confirms only the conformance wording. [19] [20]
- Pencil lead contains no lead; it is graphite with clay or polymer binder. (confidence high). Wikipedia and pencils.com agree. [5] [8]
- Only inks made for fountain pens belong in them; India ink and traditional iron gall can ruin a pen. (confidence high). Wikipedia's fountain pen and iron gall articles agree; Nibs.com advises pigment inks formulated for fountain pens plus regular cleaning. Two of the three are one publisher. [3] [4] [16]
- Gel ink resists check washing better than ballpoint ink. (confidence medium). Wikipedia says fraud-resistant gel resists acetone and check washing; WBAY (2023) reports a sheriff advising gel over ballpoint. ISO has DOC grades for ballpoint and gel, but which refills carry them, and what DOC tests, was not verified. [2] [18] [21]
- Rollerball refills can still need cartridge fit: cartridge rollerballs take ordinary fountain pen cartridges. (confidence medium). Single source: Schmidt's PRS system page ('common ink cartridges'). So the rollerball branch keeps cartridge_fit and fill_form live. [23]

## References

1. [Wikipedia, Ballpoint pen](https://en.wikipedia.org/wiki/Ballpoint_pen) (primer). Supports: Ball sizes are standard steps; ball diameter does not correspond to line width; Rollerballs use water-based ink; hybrid inks sit between ballpoint and gel; Lists ISO 12757-1, 12757-2 (DOC), 14145-1 and 14145-2 (DOC); Image caption names a large-capacity G2 type refill.
2. [Wikipedia, Gel pen](https://en.wikipedia.org/wiki/Gel_pen) (primer). Supports: Gel ink is pigment in a water-based gel; Fraud-resistant gel ink resists acetone and check washing; Gel tips are built like ballpoint tips, in small ball sizes; Many gel inks are water resistant once dry.
3. [Wikipedia, Fountain pen (Cartridges and Inks sections)](https://en.wikipedia.org/wiki/Fountain_pen) (primer). Supports: International cartridges in short and long sizes fit most pens that accept them; Pilot, Parker, Lamy, Sailor, Platinum and others use proprietary cartridges; Some compact pens take only short cartridges; some Waterman models block them; Makers discourage cheap international cartridges for uneven ink quality; Bottled ink costs less than the same amount in cartridges; Fountain inks are mostly dye; India ink and dip-pen iron gall damage pens; Platinum takes international cartridges with adaptor; Lamy unofficially fits Parker; Non-corrosive fountain inks generally exclude permanence.
4. [Wikipedia, Iron gall ink](https://en.wikipedia.org/wiki/Iron_gall_ink) (primer). Supports: Traditional iron gall clogs fountain pen feeds and corrodes metal parts; Modern fountain iron gall inks use fewer ferro-gallic compounds.
5. [Wikipedia, Mechanical pencil (Lead variations)](https://en.wikipedia.org/wiki/Mechanical_pencil) (primer). Supports: A mechanism takes a single lead diameter; Diameter table runs up to 5.6 mm; 0.5 and 0.7 balance precision and strength; Clutch pencils (leadholders) use leads of 2.0 mm and up; Pencil leads contain graphite with clay or polymer, not lead.
6. [Wikipedia, Pencil (Grading and classification)](https://en.wikipedia.org/wiki/Pencil) (primer). Supports: No common grading standard; same grade differs across makers; H to B letters with HB and F; 9H to 9B chart.
7. [Pencils.com, Graphite Grading Scale Explained](https://pencils.com/hb-graphite-grading-scale/) (spec sheet). Supports: No industry standard for darkness within the HB scale; Japanese HB is generally softer and darker than European HB.
8. [Pencils.com, The Unleaded Pencil](https://pencils.com/pages/the-unleaded-pencil) (spec sheet). Supports: There is no lead in pencils; the core is graphite.
9. [Schmidt Technology, Refills](https://www.schmidttechnology.de/en/products/writing-instruments-technology-2/refills/) (spec sheet). Supports: G2 large-capacity and D formats per DIN ISO 12757; G2 called universal; Nearly all major pen brands rely on Schmidt refills (maker's claim); Same capless rollerball tip sold in two refill lengths; Labels 0.8 and 1.0 mm ball refills M.
10. [Goldspot Pens, Ballpoint Pen Refills collection](https://www.goldspot.com/collections/ballpoint-pen-refills) (retail listing). Supports: Formats: Parker-style (ISO G2, not Pilot G2 gel), Cross, Lamy M16, Fisher SPR, D1; Advises matching format to pen model, then point size; Titles carry format, colour and point size; compatibles sold by Schmidt and Monteverde; Advises choosing ink colour; titles state the colour.
11. [Goldspot Pens, Cartridge Converter Compatibility Guide](https://www.goldspot.com/pages/cartridge-converter-compatibility-guide-for-fountain-pens) (retail listing). Supports: International cartridges come short or long and interchange across makers; Brand chart: Pilot, Platinum, Sailor, Parker, Lamy, Montblanc proprietary; Cross, Lamy, Pilot and others use several fittings by model.
12. [Goldspot Pens, What Sizes do Ballpoint Pens Come In?](https://www.goldspot.com/pages/what-sizes-do-ballpoint-pens-come-in) (primer). Supports: Defines fine, medium and broad by the width of the line written.
13. [Goldspot Pens, Ballpoint vs. Rollerball Pens](https://www.goldspot.com/pages/ballpoint-pens-vs-rollerball-pens) (primer). Supports: Ballpoint oil-based ink resists drying out and smudging; Rollerball uses much more ink than a ballpoint and needs a cap.
14. [Goldspot Pens, Mechanical Pencil Lead collection](https://www.goldspot.com/collections/mechanical-pencil-lead) (retail listing). Supports: Titles carry grade and diameter, e.g. 'Lead Refill - HB - 0.5mm'; Diameters listed from 0.5 to 5.6 mm; Colour leads are titled by colour, not grade.
15. [Nibs.com, Fountain Pen Ink Cartridges (Internet Archive, 2016)](https://web.archive.org/web/2016/http://www.nibs.com/fountain-pen-ink-cartridges.htm) (specialist review). Supports: Cartridges are international or proprietary; Aurora and Parker interchange; Pelikan international cartridges in small and large sizes; Sailor pigment cartridges are water resistant; clean pens regularly.
16. [Nibs.com, Pen Maintenance (Internet Archive, 2016)](https://web.archive.org/web/20160808175217/http://www.nibs.com/PenMaintenance.htm) (specialist review). Supports: Use pigment inks formulated for fountain pens, such as Platinum and Sailor, and clean regularly.
17. [ISO 12757-2:1998, Ball point pens and refills, Part 2: Documentary use (DOC)](https://www.iso.org/standard/23718.html) (standards body). Supports: A documentary-use (DOC) grade exists for ballpoint refills; confirmed current in 2020.
18. [WBAY, Consumer First Alert: Use gel pens to write checks (2023)](https://www.wbay.com/2023/04/30/consumer-first-alert-use-gel-pens-write-checks/) (other). Supports: Gel soaks into paper and is much harder to wash off than ballpoint ink.
19. [16 CFR 1500.14(b)(8), art materials labelling (LHAMA), via Cornell LII](https://www.law.cornell.edu/cfr/text/16/1500.14) (regulator). Supports: LHAMA makes ASTM D-4236 labelling a federal rule for art materials; Common wood pencils and single-coloured pens excluded unless marketed as art materials.
20. [CPSC, Art Materials business guidance (Internet Archive, 2025)](https://web.archive.org/web/2025/https://www.cpsc.gov/Business--Manufacturing/Business-Education/Business-Guidance/Art-Materials) (regulator). Supports: Art materials carry 'Conforms to ASTM D-4236' on the product or package.
21. [ISO 27668-2:2009, Gel ink ball pens and refills, Part 2: Documentary use (DOC) (Internet Archive, 2024)](https://web.archive.org/web/2024/https://www.iso.org/standard/44271.html) (standards body). Supports: A documentary-use grade exists for gel refills: minimum quality requirements; confirmed in 2021.
22. [ISO catalogue, ICS 01.100.40 Drawing instruments (Internet Archive, 2024)](https://web.archive.org/web/2024/https://www.iso.org/ics/01.100.40/x/) (standards body). Supports: Lists DOC parts for ballpoint (12757-2), rollerball (14145-2) and gel (27668-2) refills.
23. [Schmidt Technology, Fountain Pen Technology / Cartridge-Rollerball-System](https://www.schmidttechnology.de/en/products/writing-instruments-technology-2/fountain-pen-technology-cartridge-rollerball-system/) (spec sheet). Supports: Cartridge-rollerball system works like a fountain pen with common ink cartridges.
24. [Goldspot Pens, What are Gel Pens and How Do They Work](https://www.goldspot.com/pages/what-are-gel-pens-and-how-do-they-work) (primer). Supports: Rollerball ink is water-based and coloured with dyes, not pigments.
25. [Goldspot Pens, Water-Resistant Inks collection](https://www.goldspot.com/collections/water-resistant-inks) (retail listing). Supports: Standard dye inks do not stay put when wet; pigment and iron gall inks do; Permanent pigment inks for documents and contracts; clean pens regularly; Ink titles state colour; shop by colour.