# Paper & Cardstock

Paper divides first by job: printer paper, cardstock for crafts, art paper, or receipt rolls. Then compare weight in grams per square metre, because the pound figure in US titles depends on the paper grade: 110 lb is 199 gsm as index and 298 gsm as cover. Art paper turns on cotton versus wood pulp.

## How it works

Paper is a mat of plant cellulose fibres pressed and dried into a sheet. Weight and thickness set how stiff it is and whether a printer can feed it. The surface decides what ink or water does: sizing slows absorption, coatings hold inkjet ink on top, and calendering (pressing between rollers) makes it smoother. The fibre decides how long it lasts and how it takes water. Long cotton fibres survive scrubbing and lifting; wood pulp is cheaper and yellows and goes brittle if lignin or acid is left in. Printers add their own demands. A laser printer fuses powdered toner with heat, so a coating must tolerate heat. An inkjet sprays liquid ink, so the sheet must absorb it without spreading or cockling (going wavy). Thermal paper uses no ink: a coating of dye and developer darkens wherever the print head heats it. [14] [16] [18] [19] [4] [26] [10] [31] [36] [38]

| Family | What it is | Suits |
|---|---|---|
| Office copy and printer paper | Uncoated wood-pulp sheets, mostly 70 to 120 gsm, made to run through laser printers, copiers and inkjets. | Documents, forms, everyday printing. |
| Coated inkjet and photo paper | Paper with an ink-receiving coating in matte, satin or gloss, usually for inkjet printers only. | Photos, flyers, colour-heavy prints. |
| Cover stock (cardstock) | Heavier sheets, roughly 176 to 350 gsm, sold by cover weight in the US. | Cards, invitations, crafts, signs. |
| Art paper | Sheets made for one hand medium, from wood pulp for practice to 100% cotton for finished work. | Watercolour, drawing, pastel, mixed media. |
| Thermal paper | Rolls or sheets with a heat-sensitive coating that prints without ink. | Receipt printers, card terminals, small portable printers. |
| Plain and multi-ply register rolls | Uncoated rolls for impact printers that print through an ink ribbon; 2- and 3-ply rolls make copies. | Kitchen order printers, older tills. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Paper family
    printer paper : ask Printer compatibility, Weight (gsm), Coating finish : skip Intended medium (art paper), Thermal developer chemistry, Roll size (receipt rolls)
    cardstock and craft paper : ask Printer compatibility, Weight (gsm) : skip Intended medium (art paper), Thermal developer chemistry, Roll size (receipt rolls)
    art paper : ask Intended medium (art paper), Surface texture : skip Printer compatibility, Brightness, Thermal developer chemistry, Roll size (receipt rolls)
    receipt and thermal paper : ask Roll size (receipt rolls), Thermal developer chemistry : skip Printer compatibility, Intended medium (art paper), Fibre content, Grain direction, Surface texture
  section 2 · Printer compatibility
    Which printer model, or inkjet, laser, or not printing?
  section 3 · Intended medium (art paper)
    watercolour and wet media / mixed media : ask Weight (gsm), Fibre content
```

1. **Paper family.** Printer paper, cardstock, art paper, or receipt and thermal paper?
   Each family is judged on different specs: printer paper on printer type and weight, cardstock on cover weight and feeding, art paper on medium and fibre, receipt paper on roll size and developer. One answer retires most other families’ facets.
   If printer paper: ask Printer compatibility, Weight (gsm), Coating finish; skip Intended medium (art paper), Thermal developer chemistry, Roll size (receipt rolls).
   If cardstock and craft paper: ask Printer compatibility, Weight (gsm); skip Intended medium (art paper), Thermal developer chemistry, Roll size (receipt rolls).
   If art paper: ask Intended medium (art paper), Surface texture; skip Printer compatibility, Brightness, Thermal developer chemistry, Roll size (receipt rolls).
   If receipt and thermal paper: ask Roll size (receipt rolls), Thermal developer chemistry; skip Printer compatibility, Intended medium (art paper), Fibre content, Grain direction, Surface texture.
   Skip if already known: the project the user described (printing, cards, painting, a till), an earlier answer naming a printer or a medium.

2. **Printer compatibility.** Which printer model, or inkjet, laser, or not printing?
   Inkjet-coated photo and gloss sheets are inkjet-only because fuser heat damages the coating, while metallic and pearlescent card print better by laser. A model also gives the printer’s weight limit, which decides heavy card.
   Skip if already known: printer model, an earlier answer about the user's printer.

3. **Intended medium (art paper).** Painting with water, or drawing with pencil, pen or pastel?
   Wet media need heavy, sized sheets, with 300 gsm the usual default, and gain most from cotton, which matters less for dry sketching. Mixed-media sheets answer to both.
   If watercolour and wet media or mixed media: ask Weight (gsm), Fibre content.
   Skip if already known: the medium the user already paints or draws with.

## What to surface

### Paper family

Which kind of paper this is by the job it was made for; fine-art inkjet paper counts as printer paper, art paper means sheets for hand media, and receipt paper covers thermal rolls and sheets and plain or multi-ply register rolls. The families share almost no buying criteria. Copy paper is compared on weight and printer type, cardstock on cover weight and whether the printer can feed it, art paper on fibre, weight and surface, and receipt paper on roll size and, for thermal paper, coating chemistry. Asking a painter about brightness, or a receipt buyer about grain, wastes the question. [16] [10] [4] [26] [36] [37]

Values: printer paper, cardstock and craft paper, art paper, receipt and thermal paper.
Question to ask: Printer paper, cardstock, art paper, or receipt and thermal paper?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost low. Look for it as: Title words and product type: 'copy paper', 'printer paper', 'photo paper', 'cardstock', 'cover', 'watercolor', 'drawing', 'thermal roll', 'till roll', 'kitchen printer roll'.
Classify from the title and product type. Out of scope: foam, poster, illustration and mat board (stationery-boards); bound sketchbooks and journals (notebooks), while pads and blocks of art paper sold by weight and texture stay here; sticker, vinyl and label sheets and thermal labels (labels); pre-scored card blanks (cards).

### Intended medium (art paper)

The hand medium an art paper is made for: watercolour and other wet media, dry media such as pencil, pen and pastel, or both (mixed media). Wet and dry papers are built differently. Watercolour sheets are heavy and sized so washes can be laid, lifted and reworked; lighter sheets are more likely to buckle when wet, so painters stretch them or use a block. Dry-media papers run from smooth to a fine tooth. An answer of wet keeps watercolour and mixed-media sheets; dry keeps drawing and mixed-media sheets. [30] [28] [26] [31]

Values: watercolour and wet media, drawing and dry media, mixed media.
Question to ask: Painting with water, or drawing with pencil, pen or pastel?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost low. Look for it as: Title words: 'watercolor', 'mixed media', 'drawing', 'sketch', 'pastel', 'bristol', 'marker'.
Classify from the title. Only art paper carries this facet.

### Printer compatibility

Which printer technologies the sheet is made for: inkjet, laser, or both. Uncoated multipurpose paper around 80 to 100 gsm runs in both. Coated inkjet sheets (photo gloss, satin and textured photo card) are inkjet-only: their makers warn that laser fuser heat can damage the coating or the printer. Laser handles metallic and pearlescent card that inkjet ink smears on. A product matches an answer when its list includes that printer type. A model answer maps to its type on the maker’s page; not printing drops this filter. [23] [11] [18] [22]

Values: inkjet, laser.
Question to ask: Which printer model, or inkjet, laser, or not printing?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: Title words ('inkjet', 'laser', 'multipurpose', 'all printers') or a compatibility line in the description or FAQ, rarely a field.
Read the description text. 'Multipurpose', 'copy' and 'all printers' mean both. Coated photo or gloss sheets with no statement: treat as inkjet only and flag as inferred.

### Sheet size

The cut size of each sheet, such as US Letter (8.5 x 11 in) or A4 (210 x 297 mm). Office sizes are regional: Letter, Legal and Ledger in North America, A4 and A3 elsewhere, and the printer tray and templates follow. Craft paper has its own sizes, such as 12 x 12 in scrapbook sheets, and watercolour is sold as full 22 x 30 in sheets that are cut down. [17] [22] [27]

Values: US Letter (8.5 x 11 in), US Legal (8.5 x 14 in), Ledger (11 x 17 in), A4 (210 x 297 mm), A3 (297 x 420 mm), 12 x 12 in, full sheet (22 x 30 in), other.
Question to ask: Letter, A4, or a bigger sheet?

Used as: filter. Data: on the listing, backfill cost none. Look for it as: A 'Sheet Size' option on brand stores; in the title or spec table elsewhere. Sits in sizing.size_stated.

### Coating finish

Whether the sheet has a coating, and if so how shiny it is: matte, luster or satin, or glossy. Gloss gives the deepest blacks and the widest colour range but shows glare and fingerprints; matte reads without glare but its blacks are weaker; luster or satin sits between. Coated inkjet finishes are inkjet-only. No industry standard defines the names, so one brand's semi-gloss is another's luster. [18] [23] [13]

Values: uncoated, matte coated, luster or satin, glossy.
Question to ask: Plain, matte, satin, or glossy?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title of photo and specialty papers ('Gloss', 'Satin', 'Matte', 'C1S', 'C2S'). Absent on plain copy paper, which is uncoated.
Answer mapping: plain = uncoated. Copy and multipurpose paper with no finish stated: uncoated.

### Weight (gsm)

How much one square metre of the paper weighs, in grams; the one weight figure that compares across every grade. Weight tracks stiffness and decides whether a printer can feed the sheet and whether a watercolour sheet stays flat. US titles quote pounds instead, and pounds depend on the grade's basis sheet size: 20 lb bond, 50 lb text and 75 gsm are the same sheet, and 80 lb text (118 gsm) is thinner than 65 lb cover (176 gsm). Convert to gsm before comparing. [8] [9] [10] [14] [15] [16] [26] [27] [30]

Range: Copy paper 70 to 90 gsm and printing paper up to 120; cardstock roughly 135 to 350; watercolour 185 to 640, with 300 gsm the usual choice. Answer mapping by family, lighter below the standard band and heavier above it: printer paper standard = 75 to 80 gsm (20 to 21 lb bond); cardstock standard = 176 to 216 gsm (65 to 80 lb cover); watercolour standard = 300 gsm (140 lb). Not asked for dry-media paper.
Question to ask: Standard weight, or lighter or heavier than usual?

Used as: filter, sortable, shown on the card. Data: on the listing, backfill cost medium. Look for it as: In the title as pounds ('20lb', '65lb. Cover', '110lb') and sometimes gsm ('GSM (199)'); art papers give both ('300 gsm 140 lb'). Seen on brand stores; marketplace listings not checked.
Low for bond copy paper (16 to 32 lb) and for art paper, which states gsm; medium for cardstock, whose titles often give pounds with no grade ('110lb'). Do not guess the grade: Hammermill's 110 lb card is 199 gsm, which matches index weight, while 110 lb cover is 298 gsm. Read the brand page; convert with the gsm-from-pounds metric.
Chart: Weight ladder.

### Roll size (receipt rolls)

The width of a receipt roll plus its outside diameter or length, and sometimes its core, which must fit the printer. Receipt rolls are bought to fit one machine. Printer specs give the paper width and the largest roll the bay holds: about 58 or 80 mm wide and up to 83 mm across on an Epson and a Citizen thermal model. US listings give width by length in feet ('3 1/8" x 230''), UK listings width by diameter by core in mm ('80 x 80 x 12.7'), so the two do not compare directly. [34] [35] [36] [37] [38]

Question to ask: Which printer or terminal, or what roll width?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: In the title: US stores as width x length ('3 1/8" x 230''), UK stores as width x diameter x core in mm ('80 x 80 x 12.7 Core'). Seen on two specialist roll stores.
Parse from the title. Do not convert length to diameter; that needs the paper thickness. When only the printer model is given, read its paper width and maximum roll diameter from the maker's spec page. Thermal sheets carry sheet_size instead.

### Surface texture

How smooth or rough the uncoated surface is, from hot press (smooth) through cold press to rough, plus pressed patterns such as linen and felt. In watercolour the finish trades detail against wash evenness: hot press shows fine brushwork and bright colour but washes go blotchy, cold press is the forgiving all-rounder, and rough gives the smoothest washes. Drawing papers run from smooth to a fine 'vellum' tooth that grips graphite and pastel. Finish names are not consistent: one brand's rough can match another's cold press. [26] [29] [27] [13] [15]

Values: hot press or smooth, vellum or fine tooth, cold press, rough, linen, felt or embossed.
Question to ask: Smooth, a little texture, or rough?

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: In the title or spec table of art papers ('Cold Pressed', 'Hot Pressed', 'Rough', 'NOT', 'vellum'); cardstock names patterns ('linen', 'felt') in the title.
Answer mapping: smooth = hot press or smooth; a little texture = vellum or cold press; rough = rough or embossed. When a watercolour paper states no finish, leave it unknown rather than assume cold press.
Chart: Watercolour finish scale.

### Fibre content

What the paper is made from: 100% cotton (rag), a cotton blend, or wood pulp (often labelled cellulose or alpha cellulose). For wet media this is the spec that separates practice paper from paper for finished work. Cotton's long fibres survive lifting, scrubbing and repeated washes and are naturally acid- and lignin-free; wood-pulp paper pills or tears when overworked and is not archival. Cotton costs more per sheet, and matters less for dry sketching. Answer mapping: finished work = 100% cotton; practice = wood pulp or blend. [26] [28] [30] [27]

Values: 100% cotton, cotton blend, wood pulp.
Question to ask: Cotton for finished work, or wood pulp for practice?

Used as: filter, shown on the card. Data: on the listing, backfill cost medium. Look for it as: In the title or first line of art papers ('100% cotton', '25% cotton', 'cellulose'), seen on brand pages (Arches, Paul Rubens); student-grade lines often omit it. Absent on copy paper, which is wood pulp.
When an art paper names no fibre, record wood pulp only if the brand page says cellulose; otherwise unknown.

### Permanence

How long the paper is made to last, from no claim, through 'acid-free', to meeting a permanence standard (ISO 9706 or ANSI/NISO Z39.48). Acidic or lignin-rich paper yellows and goes brittle. 'Acid-free' alone says little: most modern paper is alkaline anyway because of its chalk filler, and some sellers call pH 6 to 7 acid-free. The standards add a pH of 7.5 to 10, a 2 percent alkaline reserve and under 1 percent lignin, and allow a circled infinity mark. [5] [6] [7] [27] [13]

Values: not stated, acid-free claimed, acid-free, lignin-free, buffered, meets ISO 9706 or ANSI/NISO Z39.48.

Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Bullet text ('acid-free', 'archival', 'lignin-free') or the brand's spec page ('permanent in accordance with ISO 9706').
Read brand pages for art and photo papers. Do not upgrade 'archival' to the standard without the standard being named.

### Brightness

How much blue light, measured at 457 nm, the sheet reflects, on the US TAPPI scale or the ISO scale. It is the number copy paper is sold on, and it measures less than it seems. The test wavelength sits inside the band where brighteners fluoresce, which is why ISO figures can pass 100. The US and ISO scales do not convert: US 92 is roughly ISO 104. Compare only within one scale, and read it as how blue-white the sheet looks, not as quality. [20] [21] [22] [27]

Range: Everyday US copy paper is sold at 92 on the US scale, roughly 104 ISO; premium colour papers go higher.

Used as: shown on the card, sortable. Data: on the listing, backfill cost low. Look for it as: In the title of US copy paper ('92 Bright', '100 Bright'). Art papers state colour ('natural white') instead.
Record the scale with the number. Do not convert between scales. Art papers name a colour ('natural white', 'bright white') instead; leave that in the product text and record brighteners under optical_brighteners.

### Thermal developer chemistry

The chemical in a thermal coating that reacts with the dye to make the mark: BPA, BPS, or a phenol-free developer. This is the one health question in the category. The developer sits loose in the coating, so it rubs onto hands; the EU has banned BPA in thermal paper at 0.02 percent or more since 2 January 2020. The ban names BPA only. 'BPA-free' can mean BPS, which acts similarly in lab tests and was under separate EU evaluation in 2020, and the US EPA found no clearly safer option among 19 alternatives. [1] [2] [3] [4] [32] [33]

Values: BPA, BPS, phenol-free, not stated.

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: A title or bullet claim ('BPA free', 'phenol free'); the developer itself is rarely named.
Record 'BPA free' with no named developer as not stated, not as phenol-free. Backfill from maker data sheets for the top rolls. Plain and multi-ply register rolls have no developer; leave this blank for them.

### Thickness (caliper)

How thick one sheet is, in points, where 1 point is one thousandth of an inch. Two sheets of the same weight can differ in thickness, depending on the fibre and how hard the sheet was calendered, and thickness is what a card feels like in the hand and what a printer's paper path resists. As a rough anchor, 10 pt card is about 245 to 250 gsm. [10] [15] [8]


Used as: shown on the card. Data: needs research, backfill cost medium. Look for it as: Rare on listings; some cardstock and print shops quote 'pt'. Brand charts give typical points per weight.
Backfill for the top cardstock products from brand pages only. Do not estimate from gsm for individual products; mcgpaper says caliper varies by 5 to 7 percent with manufacturing.
Chart: Weight ladder.

### Optical brighteners (OBAs)

Whether the paper contains fluorescent dyes that absorb ultraviolet light and give it back as blue, making the sheet look whiter. Brighteners make paper look whiter in the shop, but they fade under ultraviolet light, so the white drifts warmer over the years. Archival criteria and fine-art papers leave them out, which is why those papers look slightly warmer from the start. ISO brightness above 100 comes from brighteners. [21] [18] [27] [26] [20]


Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Stated only on fine-art, photo and archival papers ('no optical brightening agents', 'OBA-free').
Backfill for photo and art papers only. When a sheet states an ISO brightness above 100, record yes and flag as inferred. Do not infer from a US-scale number, which does not convert to ISO.

### Grain direction

Which way most fibres run in the sheet: along its length (long grain) or across it (short grain). Card folds cleanly with the grain and cracks against it unless scored first. In a printer, long-grain card resists bending round the rollers and can jam where short-grain card feeds. Most machine-made sheets are cut long grain; handmade sheets have no grain. Card makers and anyone printing heavy card on a curved paper path care. [12] [11] [14] [26]

Values: long grain, short grain, no grain (handmade), not stated.

Used as: shown on the card. Data: needs research, backfill cost high. Look for it as: Rarely stated; some cardstock shops note it in product details.
Backfill for the top cardstock products only, from brand or specialist-shop pages. Otherwise leave not stated; do not assume long grain for any given product.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Weight in gsm from a pound weight (gsm) | `pounds x 3.76 (bond) | x 1.48 (text) | x 2.70 (cover) | x 1.81 (index) | x 2.13 (watercolour, 22 x 30 in ream)` | A pound weight is the weight of 500 sheets at the grade's own basis size, so it only compares within one grade. Converting puts 20 lb bond and 50 lb text at the same 75 gsm, and shows 110 lb index (199 gsm) is far lighter than 110 lb cover (298 gsm). [8] [9] [10] [22] [26] |
| Fits the printer (yes / no) | `basis_weight_gsm <= printer maximum in pounds bond x 3.76 (tray), or the manual-feed maximum` | US printer pages state limits in pounds bond, while cardstock is sold in pounds cover. One Brother laser takes up to 43 lb bond (about 162 gsm) in the tray and 61 lb (229 gsm) by manual feed; one Brother inkjet takes 58 and 79 lb (218 and 297 gsm). [24] [25] [12] |
| Price per square metre (currency per m2) | `price / (sheet_count x sheet width in m x sheet height in m)` | Art paper comes as full sheets, pads and blocks of different sizes and counts, so price per sheet misleads; area puts a 22 x 30 in sheet and a pad of A4 on one scale. Cotton runs higher per sheet than wood pulp. [28] [27] |

## What you give up

- Heavier card feels better, but past the printer's stated limit it skews or jams, and long-grain card resists the rollers. Manual feed, a straight paper path or short-grain sheets buy some margin. [11] [12] [24] [25] Board branch: "See more printer-safe card".
- A white above 100 on the ISO scale comes from optical brighteners, which fade under ultraviolet light, so the white drifts warmer. Archival and fine-art papers leave them out and look warmer from the start. [21] [18] [27] [20] Board branch: "See more brightener-free paper".
- Hot press shows fine detail and brighter colour because paint stays on top, but washes go blotchy. Cold press is the forgiving middle, and rough gives the smoothest washes with the least detail. [26] [29] Board branch: "See more cold press".
- Cotton survives lifting, scrubbing and wet-in-wet without pilling but costs more per sheet. Wood pulp is fine for practice, colour charts and dry sketching. [28] [30] [26] Board branch: "See more practice paper".
- Gloss gives the deepest blacks and widest colour range but shows glare and fingerprints. Matte reads cleanly under any light, with weaker blacks. [18] Board branch: "See more matte".

## How to draw it

**Weight ladder** (scale, shows Weight (gsm), Thickness (caliper)). One gsm axis with each grade's pound labels hung on it shows at a glance that 20 lb bond and 50 lb text are one sheet, and that 110 lb index sits below 80 lb cover. Used today by Printers and paper shops publish it as a conversion chart (Clear Print, mcgpaper, Cardstock Warehouse).. [9] [8] [10]

**Watercolour finish scale** (scale, shows Surface texture). Hot press, cold press and rough on one line from smooth to rough, with detail falling and wash evenness rising along it, so a painter places a paper by what it does to a wash. Used today by handprint.com compares each maker's three finishes side by side.. [26]

## Words you will meet

- **gsm**. Grams per square metre, the weight of one square metre of the paper.
- **Basis weight (pounds)**. The weight in pounds of 500 sheets cut to a size that differs by grade, which is why pounds only compare within a grade.
- **Bond, text, cover, index**. US paper grades, each weighed at its own sheet size: bond for office paper, text for printing, cover for cardstock, index for stiff folders and cards.
- **Cover stock**. The grade most people call cardstock.
- **Caliper**. The thickness of a sheet, in US use given in points of one thousandth of an inch.
- **Calendering**. Pressing paper between rollers to make it smoother and denser.
- **Grain**. The direction most fibres run in a sheet; paper bends and folds more easily along it.
- **Scoring**. Pressing a line into card before folding so it bends cleanly without cracking.
- **Hot press**. Watercolour paper pressed between hot or polished rollers into a smooth surface.
- **Cold press (NOT)**. Watercolour paper with a moderate texture; NOT is the UK name, short for not hot pressed.
- **Rough**. The most textured watercolour finish, dried without pressing.
- **Vellum finish**. A fine, even tooth on drawing paper or card; not the translucent sheet also called vellum.
- **Tooth**. The fine roughness of a surface that grips pencil, charcoal or pastel.
- **Sizing**. A treatment, such as gelatin, added to paper to slow how fast it absorbs water.
- **Cotton rag**. Paper made from cotton fibres rather than wood, prized for strength and permanence.
- **Alpha cellulose**. The stable part of plant fibre; on art paper labels it usually means purified wood pulp.
- **Cockling**. Paper going wavy where it got wet.
- **Lignin**. The natural glue in wood that turns paper yellow and brittle as it ages.
- **Alkaline reserve (buffered)**. Chalk-like filler left in paper to neutralise acids that reach it later.
- **ISO 9706**. The international standard for permanent paper, matched in the US by ANSI/NISO Z39.48; compliant paper may carry a circled infinity sign.
- **Optical brightener (OBA)**. A fluorescent dye that turns invisible ultraviolet light into blue so paper looks whiter.
- **TAPPI and ISO brightness**. Two different test scales for paper brightness, used in the US and elsewhere, that do not convert into each other.
- **C1S, C2S**. Coated on one side, coated on both sides.
- **Direct thermal**. Printing by heating a coated paper so it darkens, with no ink or toner.
- **Developer**. The chemical in a thermal coating that makes the dye change colour when heated.
- **BPA and BPS**. Bisphenol A and bisphenol S, related chemicals used as thermal developers and studied as hormone disruptors.

## Where we made a call

- Compare paper on gsm; a pound weight means nothing without its grade, and 110 lb can be 199 or 298 gsm. (confidence high). Every conversion chart says the same, and handprint says to think in gsm. Hammermill's 110 lb cardstock is 199 gsm, which matches index weight, though Hammermill does not name the grade. Ours, built on those sources. [26] [10] [9] [22]
- Brightness numbers compare only within one scale, and ISO values above 100 come from brighteners, so they rank looks, not quality. (confidence high). TAPPI and ISO use different tests and do not convert; brightness is measured at 457 nm, where brighteners fluoresce. [20] [21]
- 'Acid-free' on everyday paper says little; only a named permanence standard (ISO 9706 or Z39.48) is a real longevity claim. (confidence medium). Sources disagree. Sources set the acid-free line at pH 7 (Cardstock Warehouse) or accept 6 to 7 (Wikipedia). The standards require 7.5 to 10 plus a reserve, so we side with the standards. [7] [13] [5] [6]
- For watercolour, 300 gsm (140 lb) is the default weight; lighter sheets buckle more easily, so are often stretched or used as a block. (confidence high). Paul Rubens, Edinburgh Art Workshop and handprint agree. Edinburgh's tutor also likes 250 gsm because it does not buckle, and Paul Rubens says very wet work may still need stretching at 300, so it is a default, not a law. [28] [30] [26]
- Cotton matters most for wet techniques and finished work; for dry sketching and practice, wood pulp is enough. (confidence medium). Paul Rubens says so directly; handprint adds that wood pulp is not archival. Paul Rubens is a seller of cotton paper, so we lean on handprint and Edinburgh too. [28] [26] [30]
- Finish names are not standardised: one brand's rough can be another's cold press, and gloss names vary by maker. (confidence high). handprint for watercolour finishes; Wikipedia for inkjet finishes, where no industry standard defines glossy or semi-matte. [26] [18]
- Coated inkjet photo and specialty sheets should be treated as inkjet-only unless the maker says laser-safe. (confidence high). mcgpaper warns on several products that fuser heat damages the coating; laser-rated coated papers exist and say so (Hammermill Color Copy Cover). [23] [22] [19]
- A 'BPA-free' receipt roll is not necessarily bisphenol-free or safer; only 'phenol-free' rules out BPS. (confidence medium). EPA found no clearly safer alternative among 19 it assessed. ECHA’s 2020 survey put BPA at 29% of EU thermal paper in 2019 and forecast BPS at 61% by 2022. The EU ban names BPA only. [3] [4] [1] [32] [33]

## References

1. [Commission Regulation (EU) 2016/2235 amending REACH Annex XVII as regards bisphenol A (via Internet Archive)](https://web.archive.org/web/2023/https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32016R2235) (regulator). Supports: BPA at 0.02% or more banned in EU thermal paper after 2 January 2020; risk to unborn children of exposed workers and consumers.
2. [ChemSafetyPro: Regulation (EU) 2016/2235 adds BPA to REACH Annex XVII](https://www.chemsafetypro.com/Topics/Restriction/Regulation_EU_2016_2235_Bisphenol_A_BPA_ban_thermal_paper_REACH_annex_xvii.html) (primer). Supports: entry 66, 0.02% by weight, after 2 January 2020.
3. [US EPA Design for the Environment: Bisphenol A Alternatives in Thermal Paper (final report, January 2014)](https://www.epa.gov/sites/default/files/2014-05/documents/bpa_final.pdf) (regulator). Supports: BPA in receipts is free, unbound, and more available for exposure; 19 alternatives assessed; none clearly safer than BPA.
4. [Wikipedia: Thermal paper](https://en.wikipedia.org/wiki/Thermal_paper) (primer). Supports: coating of leuco dye and developer darkens with heat; BPS used from about 2013; phenol-free urea or vitamin C developers cost more; used in cash registers and card terminals.
5. [Ellen McCrady, The ANSI/NISO Z39.48 Standard and Other Standards (Abbey Publications, on CoOL)](https://cool.culturalheritage.org/byorg/abbey/napp/std.html) (primer). Supports: Z39.48: pH 7.5 to 10, 2% alkaline reserve, 1% lignin maximum; ISO 9706 very similar, Kappa number 5.
6. [Library of Congress, Ask a Librarian: What is permanent paper?](https://ask.loc.gov/preservation/faq/337512) (other). Supports: permanent paper: 2% alkaline reserve, under 1% lignin, pH 7.5 to 10.
7. [Wikipedia: Acid-free paper](https://en.wikipedia.org/wiki/Acid-free_paper) (primer). Supports: much modern paper is acid-free because of calcium carbonate filler; some call pH 6 to 7 acid-free; circled infinity mark for ISO 9706 or Z39.48.
8. [mcgpaper: Paper weights and conversion tables](https://mcgpaper.com/pages/how-to-make-paper-weights-and-conversion-tables) (primer). Supports: basis sizes: bond 17 x 22, text 25 x 38, cover 20 x 26 in; 20 lb bond = 75.2 gsm; 10 pt near 244.5 gsm; caliper varies 5 to 7% with manufacturing; 80 gsm / 21 lb is standard copy paper.
9. [Clear Print: GSM Paper Weight Chart](https://www.clearprint.com/gsm-paper-weight-chart/) (primer). Supports: 20 lb bond and 50 lb text both 75 gsm; 110 lb index 200 gsm; 65 lb cover 175 gsm; 80 lb cover 215 gsm.
10. [Cardstock Warehouse: Paper 101, Paper Weight Guide](https://cardstock-warehouse.com/pages/cardstock-paper-basis-weight-chart) (primer). Supports: 80 lb text is 118 gsm, thinner than 65 lb cover at 176 gsm; cover weights 176 to 352 gsm; cardstock is cover paper; same weight can differ in caliper because of fibre and calendering; 80 lb cover sold as the sturdy everyday sheet.
11. [Cardstock Warehouse: Paper 101, Printing on Cardstock](https://cardstock-warehouse.com/pages/cardstock-paper-101-printing) (primer). Supports: long-grain card resists printer rollers and may jam; inkjet smears on coated reflective paper; laser prints metallic and pearlescent.
12. [Cardstock Warehouse: Paper 101, Scoring, Folding and Paper Grain](https://cardstock-warehouse.com/pages/cardstock-paper-101-scoring-and-folding) (primer). Supports: folding is easier with the grain; scoring prevents cracking; check the printer can handle the card's gsm.
13. [Cardstock Warehouse: Paper 101, Glossary of Terms](https://cardstock-warehouse.com/pages/paper-101-glossary-of-terms) (primer). Supports: acid-free defined as pH 7.0 or more; antique vellum is a fine-tooth finish; C1S and C2S coatings; calendering.
14. [Wikipedia: Paper](https://en.wikipedia.org/wiki/Paper) (primer). Supports: printing paper 60 to 120 gsm; over 160 gsm is card; sheets usually cut long grain; handmade paper lacks grain direction.
15. [Wikipedia: Card stock](https://en.wikipedia.org/wiki/Card_stock) (primer). Supports: cardstock about 135 to 300 gsm; 10 pt card is 0.010 in, about 250 gsm; finishes include wove, laid, felt, linen.
16. [Wikipedia: Special fine paper (copy paper)](https://en.wikipedia.org/wiki/Copy_paper) (primer). Supports: copy paper 70 to 90 gsm, for copiers and laser printers; made of virgin chemical pulp or deinked pulp.
17. [Wikipedia: Paper size](https://en.wikipedia.org/wiki/Paper_size) (primer). Supports: Letter 8.5 x 11 in in North America; A4 210 x 297 mm elsewhere.
18. [Wikipedia: Inkjet paper](https://en.wikipedia.org/wiki/Inkjet_paper) (primer). Supports: 80 to 100 gsm office paper works in inkjet and laser; gloss gives widest gamut; matte weaker blacks; no standard defines glossy; longevity needs no brighteners; fine-art inkjet papers usually cotton rag.
19. [Wikipedia: Laser printing](https://en.wikipedia.org/wiki/Laser_printing) (primer). Supports: toner is fused onto paper with heat and pressure.
20. [Wikipedia: Bleaching of wood pulp, section Paper brightness](https://en.wikipedia.org/wiki/Bleaching_of_wood_pulp) (primer). Supports: TAPPI in the US, ISO elsewhere; no simple conversion; TAPPI 92 corresponds to about ISO 104; ISO can exceed 100 from brighteners; ISO values above 100 come from fluorescent whitening agents.
21. [Wikipedia: Optical brightener](https://en.wikipedia.org/wiki/Optical_brightener) (primer). Supports: brightness measured at 457 nm, inside brighteners' fluorescent range; common brighteners fade under prolonged ultraviolet exposure.
22. [Hammermill store product feed (products.json)](https://www.hammermill.com/products.json) (spec sheet). Supports: titles carry pound weight and brightness: '20lb, 92 Bright', '100 Bright'; 110 lb cardstock listed at 199 gsm, matching index weight; grade not named; options list basis weight, sheet size and pack size.
23. [mcgpaper product feed (products.json), product FAQs](https://mcgpaper.com/products.json) (spec sheet). Supports: inkjet gloss and microporous coatings not for laser; fuser heat damages them; compatibility stated in FAQ text, not a field.
24. [Brother HL-L2350DW product page](https://www.brother-usa.com/products/hll2350dw) (spec sheet). Supports: tray 16 to 43 lb bond; manual feed 16 to 61 lb bond.
25. [Brother MFC-J4335DW product page](https://www.brother-usa.com/products/mfcj4335dw) (spec sheet). Supports: tray 17 to 58 lb bond; manual feed 17 to 79 lb bond.
26. [handprint.com (Bruce MacEvoy): watercolor papers](https://www.handprint.com/HP/WCL/paper1.html) (enthusiast community). Supports: 140 lb = 300 gsm, 300 lb = 640 gsm; think in gsm across makers; hot press detail but blotchy washes; cold press forgiving; rough smoothest washes; finish names vary by brand; wood pulp not archival; no brighteners; machine-made grain runs the length of the web.
27. [Arches: ARCHES Aquarelle product page](https://arches-papers.com/arches-range-of-papers/watercolor-and-wet-techniques/arches-aquarelle/) (spec sheet). Supports: 100% cotton, gelatin sized, no brighteners, ISO 9706; 185 to 850 gsm; 300 gsm = 140 lb; CP, HP, rough; 22 x 30 in sheets; colour sold as natural white or bright white, with no brightness number.
28. [Paul Rubens Shop: 100% Cotton Watercolor Paper, When It Matters](https://www.paulrubensshop.com/blogs/knowledge/watercolor-paper-complete-guide) (primer). Supports: 300 gsm / 140 lb as default weight; cotton better for lifting and scrubbing; cellulose pills; cotton costs more per sheet; cotton less necessary for dry sketching.
29. [Paul Rubens Shop: Watercolor Paper Texture](https://www.paulrubensshop.com/blogs/knowledge/watercolor-paper-texture) (primer). Supports: cold press as the versatile choice; hot press for detail and scanning; texture does not replace weight or cotton.
30. [Edinburgh Art Workshop: Finding the Right Paper](https://www.edinburghartworkshop.com/articles/finding-the-right-paper) (primer). Supports: watercolour weights 190 to 638 gsm; 300 gsm and up resists buckling; stretch paper under 300 gsm; cotton for finished work, wood pulp for practice.
31. [Wikipedia: Watercolor paper](https://en.wikipedia.org/wiki/Watercolor_paper) (primer). Supports: hot press, cold press and rough finishes; gelatin sizing reduces damage from repeated wetting and reworking.
32. [ECHA news release ECHA/NR/20/22: Bisphenol S has replaced bisphenol A in thermal paper (18 June 2020, via Internet Archive)](https://web.archive.org/web/2021/https://echa.europa.eu/-/bisphenol-s-has-replaced-bisphenol-a-in-thermal-paper) (regulator). Supports: 61% of EU thermal paper forecast BPS-based by 2022; BPA still 29% of the EU market in 2019; BPS under separate EU evaluation and a classification proposal in 2020.
33. [ECHA: The use of bisphenol A and its alternatives in thermal paper in the EU during 2014 - 2022 (ECHA-20-R-07-EN, June 2020, via Internet Archive)](https://web.archive.org/web/2021id_/https://echa.europa.eu/documents/10162/2564887/bpa_thermal_paper_report_2020_en.pdf/59eca269-c788-7942-5c17-3bd822d9cba0) (regulator). Supports: 2019 shares: BPA 29%, BPS 39%, other developers 32%; 2022 forecast: BPS 307 kilotonnes, 61% of total.
34. [Epson OmniLink TM-T88VI thermal receipt printer, product page](https://epson.com/For-Work/Printers/POS/OmniLink-TM-T88VI-Thermal-Receipt-Printer/p/C31CE94061) (spec sheet). Supports: roll 79.5 or 57.5 mm wide, up to 83 mm diameter.
35. [Citizen CT-E351 POS printer, product page](https://www.citizen-systems.com/us/printer/pos/ct-e351) (spec sheet). Supports: paper width 58 and 80 mm; roll up to 83 mm outside diameter.
36. [Epson TM-U220 impact receipt printer, product page](https://epson.com/For-Work/Printers/POS/TM-U220-Impact-Receipt-Printer/p/C31C514653) (spec sheet). Supports: impact printer with ribbon cassette for kitchen orders; 58, 70 or 76 mm rolls, 83 mm diameter; one original and one copy.
37. [POSPaper.com store product feed (products.json)](https://www.pospaper.com/products.json) (retail listing). Supports: US roll titles give width x length in feet, e.g. 3 1/8" x 230'; thermal sheets sold for Brother PocketJet printers.
38. [Till Rolls Direct (UK) store product feed (products.json)](https://www.tillrollsdirect.co.uk/products.json) (retail listing). Supports: UK roll titles give width x diameter x core in mm, e.g. 80 x 80 x 12.7; 2-ply and 3-ply 76 mm kitchen printer rolls.