Paper Stock for Art Prints: GSM, Ink and Print Methods

Two quotes for "the same" print differ because it is not the same print: the sheet, the ink and the process all move the price, and none of the three shows in a photograph. GSM is grams per square metre — mass per unit area, and nothing more — so it tells you how heavy a sheet is and says nothing about its surface, its whiteness, or how long the image lasts. What follows is what each specification predicts, how surfaces and ink types differ, where offset beats inkjet, how to read a spec sheet, and what to ask a supplier.

Key takeaways

• GSM means grams per square metre; as a mass per area it predicts neither the surface nor the whiteness nor the permanence of a print.
• Sheet weight is arithmetic: a 50 × 70 cm sheet is 0.35 m², so it weighs 70 g at 200 gsm and 105 g at 300 gsm, and a 70 × 100 cm sheet weighs twice as much at any weight.
• Coated papers hold ink near the surface and give darker blacks and sharper type; uncoated papers let ink soak in, softening edges and lightening blacks but removing glare under shop lighting.
• Pigment inks are solid particles held on or near the surface by a binder, so they resist light, water and airborne pollutants far better than dye inks, which dissolve into the coating.
• "Giclée" is a marketing word for large-format inkjet printing with no standard definition, so it tells you nothing about the paper, the ink set or the print's permanence.
• "Archival" is unregulated, and it means something only when the supplier states which claim is being made — acid-free, lignin-free, buffered, pigment ink — and against what standard.

What GSM actually measures, and what it does not

Grams per square metre is a mass per area, and that is the entire definition: a 200 gsm sheet is one whose square metre weighs 200 grams, whether it is glossy or rough, bright white or cream.

The arithmetic you can redo

Multiply a sheet's area in square metres by the GSM to get its weight in grams; the three standard formats are 0.12 m², 0.35 m² and 0.70 m².

So "heavy" means nothing until you say what size it is heavy for: a 70 × 100 cm sheet at 200 gsm weighs the same as a 50 × 70 cm sheet at 400 gsm. It is also the number that enters your freight calculation.

What GSM does not predict

Almost every wrong comparison here comes from assuming one of these:

• Surface. A 200 gsm sheet can be glassy gloss, satin, matte, or rough enough to pass for watercolour paper.
• Whiteness. Two 230 gsm sheets can sit far apart on any whiteness scale, and one may be white only because of an additive.
• Permanence. A heavy sheet of mechanical pulp yellows faster than a lighter purified one.
• Colour performance. The coating decides how dark the black goes, not the weight.
• Flatness. A heavy uncoated sheet can cockle under dense ink while a lighter resin-coated one stays flat.

GSM, pounds and caliper

North American quotes often come in pounds — the weight of 500 sheets at that grade's basis size, which differs by grade: text papers use 25 × 38 in, cover papers use 20 × 26 in. Since 1 lb is 453.6 g, one pound of text over 0.6129 m² is 1.48 g/m² and one pound of cover over 0.3355 m² is 2.70 g/m² — so 80 lb text is about 118 gsm while 80 lb cover is about 216 gsm. Convert before comparing. Caliper, or thickness, comes in microns or points, where one point is 0.001 in or 25.4 microns; as a rule of thumb it rises with weight within one paper family and not across families, because mineral coating is denser than fibre.

The weight bands you will be quoted

These are industry conventions rather than standards, but they hold well enough to read a quote with: 120–170 gsm is poster stock, which rolls easily and creases in a browser bin; 180–220 gsm is the default art-print band; 230–260 gsm is heavy matte and photo lustre, and the sensible floor for 70 × 100 cm; 280–330 gsm is cotton rag and textured sheets; 350 gsm and above is board rather than paper.

Coated, uncoated and textured: what the surface does

The surface is where the money is: it decides how much ink the sheet accepts, how dark the black goes and whether the print glares under your lighting.

Uncoated paper has no surface layer, so ink goes into the fibre and spreads. Blacks read as dark grey, dot gain softens fine strokes and the surface marks more easily. The compensation matters for reference charts: a matte sheet does not mirror the ceiling lights, so small type stays readable from an angle. Under strong downlights that beats the extra density of a coated sheet.

Coated paper carries a mineral layer — usually calcium carbonate or kaolin clay — held on the base with a binder. Ink sits in or on it, so dots stay put and more colourant stays visible: a higher maximum black, a wider range, sharper type. Three coating families matter for inkjet: microporous, a porous silica or alumina layer that absorbs the carrier almost instantly, its open pores leaving the colourant more exposed to airborne pollutants; swellable polymer, which encapsulates the colourant and prints a deeper black but needs drying time before stacking; and resin-coated, where the base is sandwiched between polyethylene layers, giving a stable sheet that dries instantly but reads as a photograph.

Gloss gives the deepest black and widest gamut and is the worst choice under a light; satin is the compromise. Textured and mould-made sheets look expensive and hide handling marks, at two costs: texture breaks up the ink film so very small type loses definition, and they cost the most.

The fibre underneath matters more than the texture. Cotton rag is naturally lignin-free and costs the most. Alpha-cellulose is purified wood pulp with the lignin removed; when lignin-free and buffered it can approach cotton on permanence, though not on feel. Mechanical pulp still contains lignin, yellows and embrittles, and has no place in a print sold as permanent.

Cost tiers are relative within one supplier's range, not absolute: "premium" is a position in someone's list, not a grade you can compare across suppliers without the specification.

Whiteness, optical brighteners and why paper yellows

Whiteness is the specification most often quoted and least often explained, and it decides whether a delivery matches the sample you approved. Brightness and whiteness differ: brightness measures reflectance at one blue wavelength, whiteness the distance from a defined white point across the visible range. Papers with fluorescent additives can report a CIE whiteness above 100, because they emit more blue light than they receive — not an error, and not a better paper. Ask too for the b value, the blue-yellow axis: negative is blue-biased, positive is warm, and two sheets sold as the same "bright white" with different b values will not produce matching prints.

Optical brightening agents (OBAs) are fluorescent compounds that absorb ultraviolet and re-emit it as blue, masking the cream tone of the fibre. Two things go wrong: the effect decays, so the sheet drifts warmer and duller, first beside a frame or at the edge of a window display; and the colour becomes dependent on the light source: an OBA-loaded sheet looks bright under daylight or fluorescent tubes, which contain ultraviolet, and duller under an LED fixture with almost none. Most commercial papers contain them and bright white sells, but know whether the sheet you are quoting does.

Three terms are constantly confused. Lignin-free means the polymer that makes paper yellow and brittle as it oxidises has been removed, and it matters most. Acid-free means the sheet was made under neutral or alkaline conditions — a description of manufacture, not a guarantee. Buffered means an alkaline reserve, typically calcium carbonate, neutralises acids picked up later. A sheet can be acid-free and still contain lignin, and none of the three says anything about the ink.

"Archival" has no legal or standard definition for a consumer print in most markets; it is a word a supplier applies to its own product. Ask which claim is being made: the substrate is lignin-free and buffered, the ink is pigment, the combination was tested to a named standard, or all three. A real standard for permanent paper does exist — ISO 9706, which sets requirements including pH and alkali reserve — so a supplier who names it is making a checkable claim, and one who writes only "archival quality" is not.

The rule of thumb: a print lasts only as long as its least stable component — pigment ink on a groundwood sheet still yellows, and dye ink on cotton rag still fades.

Pigment ink and dye ink: what is on the paper

This is the biggest divider between a cheap print and an expensive one, and it is invisible in a photograph.

A dye ink is a colourant dissolved in a carrier at the molecular level. It penetrates the coating, which makes dye inks vivid and smooth in their gradations. The weakness is structural: a dissolved molecule is individually exposed to light, humidity and pollutants, with nothing shielding it.

A pigment ink is a suspension of solid particles, milled to sub-micron size, carried in a liquid with a resin binder. Once the carrier is absorbed or evaporated, the binder holds the particles on or near the surface. The particles are larger and shielded, so pigment resists light, water and atmospheric gases far better. Historically it had a narrower gamut and could show gloss differential — a bronzing or sheen shift on glossy media — and modern sets have narrowed rather than closed that gap. Pigment is also the more forgiving choice on matte sheets, because it does not depend on a receptive coating; dye inks really do need one.

Ink set size is the other variable. A basic set is four colours; extended sets add light cyan, light magenta, greys, photo and matte black, sometimes orange, green or violet. More inks buy smoother gradients and neutral greys and cost more per print. On a chart with large flat colour areas — a star-chart sky, a colour-coded timeline — the difference shows there, where banding appears first. On a line drawing it does not.

Print methods: offset, large-format inkjet, resin and UV

Offset lithography is indirect: the image sits on a plate, transfers to a rubber blanket, then to the sheet. The ink is a viscous paste and colour comes from a halftone screen, typically 150 to 175 lines per inch, not continuous tone. It wins on unit cost at volume, on spot colours and finishes — a premixed ink, a metallic, a varnish, none of which aqueous inkjet can lay down — and on sharpness for small type. It loses on fixed cost, because plates and makeready are paid before the first good sheet, on short runs, and on waste getting up to colour. Process-control standards exist, such as ISO 12647, so "printed to a standard" is a meaningful claim in a way that "archival" is not.

Large-format inkjet uses drop-on-demand heads, usually piezoelectric in production machines, to place very small droplets of aqueous ink. There is no plate, and colour is built by dithering rather than a fixed screen, so output can look continuous-tone. It wins on short runs, on size, on gamut where an extended set on a coated sheet can exceed standard four-colour offset, and on inventory risk — which is why a range of 14 SKUs can be supplied without stock of every title. It loses on unit cost, which barely falls with volume, on speed for long runs, and on spot colours. The point that matters most: inkjet is profiled per stock — the same file on two papers needs two profiles, and a run on the wrong one will not match your sample.

"Giclée", said plainly. It is a marketing word, coined in the early 1990s for inkjet output sold as fine art, and it carries no standard definition, no certifying body and no minimum specification. In practice it means anything from "pigment on cotton rag, proofed and profiled" to "we printed this on the wide machine". The paper, ink set, method and profile are the information; the word is not.

Resin, latex and UV-curing matter for rolled goods, canvas and high-traffic settings:

• Latex (resin) ink. A water-based latex polymer cured by heat in the printer; dries immediately, low odour, cures to a flexible film, so it is the usual choice for canvas that will be stretched. Softer than a UV-cured film and abrades more easily.
• UV-curing ink. Monomers and oligomers cured instantly by ultraviolet lamps into a solid film. Very durable and able to print on non-porous substrates, at the cost of a heavier film, a sheen, and a tendency to crack rather than stretch at a sharp fold.

Where the break-even sits

The cross-over is not a fixed number of units; it is arithmetic:

“Break-even quantity = (plate and makeready cost) ÷ (inkjet unit cost − offset unit cost)”

With assumptions you should replace with your supplier's own: plates and makeready of 240 USD, an inkjet unit at 3.20 USD, an offset unit at 1.20 USD. The difference is 2.00 USD, so the break-even is 120 units of one image. Press format, shared plates and finishing all move it.

How to choose a stock and a method

Work through this in order; each step removes options rather than adding them.

1. Decide where the print will live. Framed behind glass gives you the widest choice; a browser bin punishes anything under 200 gsm and any glossy surface that shows fingerprints.
2. Decide how much light it will get. A window display gets a great deal of ultraviolet; if so, pigment ink and a low-OBA sheet are worth paying for.
3. Choose the surface from your lighting, not from a sample book. Under strong downlights, matte or satin keeps a text-dense chart readable. Gloss is for photography-led work.
4. Choose the weight from the format. As a rule of thumb for unframed hanging: 200 gsm is fine at 30 × 40 cm, adequate at 50 × 70 cm, marginal at 70 × 100 cm, where 230 gsm is the floor.
5. Choose the ink. Pigment, unless the item is explicitly short-life promotional material.
6. Choose the method from the run length. Compute the break-even above. Ordering 50 units per SKU puts you almost certainly below it, which is why a wide range is normally inkjet-produced.
7. Ask for a proof on the actual stock at the actual size. A proof on a different paper tells you nothing about the final colour, because the profile is per stock.
8. Write the specification down — paper, GSM, ink, method, profile. That line is what you check the next batch against.

How to read a print specification sheet

This turns the rest into a purchasing decision: put the printed specification sheet beside the quote and check each line.

Red flags in a quote: "archival" or "museum quality" with no standard and no substrate; a GSM figure and nothing else; "premium 250gsm paper", where the word doing the work is premium; ink type not mentioned; and a price close to a competitor's while the paper specification is vaguer. Always get a printed sample on the exact stock and keep it as your reference.

Questions to put to a supplier before the first order

Send this before the purchase order, not after the invoice.

• Which paper, by maker and name — not "200gsm art paper"?
• What finish: matte, satin, gloss or textured?
• Is it coated, and with which coating family?
• Is it lignin-free, acid-free and buffered, with an alkaline reserve?
• Does it contain optical brighteners, and roughly how much?
• Is the ink pigment or dye, and how many inks in the set?
• Which print method, and is colour profiled per stock?
• Is the sample I received printed on the stock the order will use?
• Is the minimum 50 units per SKU across all 14 SKUs and all sizes?
• Do cases ship in multiples of 1, and is there a cart minimum?
• Is 7 business days the whole wait or only the print stage?
• Are the payment terms 30 days?
• Does the order clear 3,500 USD, and if paying by bank transfer does it pass 2,000 USD?

The commercial answers are on the wholesale terms page; the technical ones decide whether you are buying what you think you are.

How paper choice changes packing and freight

Paper enters the freight calculation in four places.

Dead weight. Fifty 50 × 70 cm prints weigh 3.5 kg of paper at 200 gsm, 5.25 kg at 300 gsm. On a rolled shipment that rarely decides anything, because the tube and the volumetric weight dominate; see volumetric weight and reference chart freight for where the breakpoint falls.

Stiffness and corner damage. Heavier sheets resist creasing in a browser bin, but a heavier carton is handled harder and one not rated for the weight crushes at the corners regardless of the contents. Packing and paper have to be specified together, which is the argument for reading what actually ships in the box before choosing a stock on price.

Flatness after unrolling. A rolled print has memory: as a rule of thumb, heavier sheets hold their set curl more strongly and take longer to relax — overnight under weight is usually enough at 200 gsm, and 300 gsm can want longer. A sheet is also stiffer across the grain, so rolling with it reduces curl.

Humidity. Uncoated and cotton rag sheets are hygroscopic and will cockle in a damp stockroom; coated and resin-coated sheets are more dimensionally stable. In a basement stockroom that argument beats any colour consideration.

None of these change the retail price; they change how many units you write off, which is a margin question, and the arithmetic belongs with pricing reference charts so the margin survives the rent.

Frequently asked questions

What GSM should an art print be?

For an unframed print, 200 gsm is the working default and 230–260 gsm the safe range at 50 × 70 cm and above. Below 170 gsm a sheet curls and creases in a browser bin; above 300 gsm you pay for weight a customer cannot see.

Is 200gsm or 300gsm better for a poster?

300 gsm is stiffer and more opaque, but GSM says nothing about surface or whiteness, so the real question is which 200 gsm and which 300 gsm. With the same finish and fibre, take 200 gsm at 30 × 40 cm and 300 gsm at 70 × 100 cm; at 50 × 70 cm, spend the difference on a coated or pigment-inked option.

What is the difference between giclée and a lithograph?

A lithograph is printed by offset lithography from plates, at a fixed screen ruling, with a high fixed cost and a low unit cost. Giclée is a marketing term for large-format inkjet printing with no standard definition, so it specifies no particular paper, ink or permanence. Compare the specifications underneath the word.

Are pigment inks really more fade resistant than dye inks?

Yes, and the mechanism is straightforward: pigment colourant is solid particles held on or near the surface by a binder, while dye colourant dissolves into the coating, exposed to light, humidity and pollutants. How much longer a pigment print lasts depends on the paper, the light level and the pollutants, which is why no supplier can honestly quote a number of years without the conditions.

Does acid-free paper mean the print will not fade?

No. Acid-free describes the paper and says nothing about the ink on top of it. A print's life is set by its least stable component, so an acid-free sheet carrying dye ink will still fade.

What to do next

1. Take one print you already stock, find its GSM, finish and ink type, and write all three on the stock card — if you cannot find two of the three, that is the problem in one line.
2. Send the checklist above to your current supplier and to one alternative, put the answers side by side, and price the difference per unit against what you charge.
3. Settle the format question first — print, scroll or frame — then set one house paper and ink across the range, so reorders match: a title such as the Twenty-Eight Mansions star chart at 50 × 70 cm is only as consistent as the specification behind it.