Paper & GSM Guide for Printing in India — Art Paper, Art Card, Maplitho, Duplex and Board Explained

What GSM actually measures

GSM is grams per square metre. It is a weight, and only a weight. It tells you what one square metre of that paper weighs and nothing at all about how thick it is, how stiff it is, how opaque it is or how it will take ink. This is the source of almost every paper misunderstanding in a print specification.

The property you actually feel when you handle a sheet is caliper — its thickness — and the relationship between GSM and caliper depends on bulk, which varies enormously between paper types. A 300 GSM art card and a 300 GSM duplex board weigh exactly the same and behave completely differently: the duplex is noticeably thicker and stiffer, because its recycled core is bulkier, while the art card is denser, smoother and prints a sharper image. Specify 300 GSM without naming the paper type and you have specified almost nothing.

The second property that matters and is not GSM is opacity — how much of the print on the reverse shows through. Opacity rises with weight, but it also rises with filler content and with bulk, which is why a 70 GSM high-opacity maplitho can be more usable for a book than an 80 GSM cheap sheet. On a diary, a notebook or a book, opacity is the specification that determines whether the product feels good, and it is the one nobody asks about.

The practical rule: name the paper type, then the GSM, then the mill or the brightness if it matters. “One hundred GSM art paper” is a specification. “One hundred GSM” is not.

Coated or uncoated — the choice nobody explains properly

A coated sheet has a mineral layer on its surface that stops ink soaking into the fibre. The ink sits on top, stays where it is put, and dries with its colour intact. That is why a photograph on art paper looks sharp and saturated, and the same photograph on maplitho looks flat and slightly grey — the ink has spread into the fibre, a phenomenon called dot gain, and every fine detail has thickened slightly.

Uncoated sheets take a pen, feel warmer, and are what anything meant to be written on must be. Coated sheets do not take most pens reliably, which is why an art-paper diary is a bad idea however good it looks in a photograph. That single rule resolves most coated-versus-uncoated arguments: if a human will write on it, use uncoated; if a human will only look at it, use coated.

There is a middle ground worth knowing about. Matt-coated art paper has the coating but a low-gloss finish, so it holds image detail while being much easier to read long passages of text on than gloss. It is what good catalogues and most annual reports use. It costs marginally more than gloss art paper and is almost always the better choice for anything with more than a paragraph of body text on it.

One practical warning: ink dries much more slowly on coated stock, because it cannot soak in. A heavy 4-colour job on 130 GSM art paper needs real drying time between the press and the folding machine, and a job that is rushed through will set off — the wet ink on one sheet transferring onto the back of the sheet above it. If a schedule looks too fast for the ink coverage, that is what the press is worried about.

How paper choice changes your price — a worked example

Take a 5,000-piece run of a 4-page A4 brochure, 4-colour both sides. On 130 GSM art paper the band is ₹4–₹7 a piece. Paper is roughly 45% of that, so about ₹1.80–₹3.15 of it is the sheet.

Step up to 170 GSM and the paper weight rises by about 31%. Paper cost rises roughly in proportion, adding about ₹0.55–₹0.98 a piece, which lands you around ₹4.55–₹8.00 — and that is before any extra drying time. Step down to 100 GSM instead and you save roughly ₹0.42–₹0.73, landing around ₹3.60–₹6.30, at the cost of visible show-through on a dark-backed page.

Now change type rather than weight. Move the same brochure from 130 GSM art paper to 130 GSM maplitho and the paper gets cheaper by roughly 20%, saving about ₹0.36–₹0.63 a piece — but the images lose their snap entirely and the piece reads as a handout. Move it from art paper to matt-coated art at the same weight and you pay a few paise more and get a better-looking job. The lesson is consistent: changing type usually changes perceived quality more than it changes price, and changing weight usually changes price more than it changes perceived quality.

The one change that beats both is quantity. The same brochure at 1,000 pieces is ₹8–₹12 and at 50,000 is ₹2.20–₹4.00. No paper decision available to you is worth anything like that. The cost guide has the full matrices.

Glossary of Indian print trade terms

Deckle

The width of a reel or sheet as the mill supplies it. It determines how your job imposes and how much of every sheet is trimmed away unused.

Ream

Five hundred sheets. Paper is bought and priced by weight, but counted and stored by the ream.

Bundle

A packed quantity of finished pieces, usually 25, 50 or 100, shrink-wrapped before going into an outer carton.

Make-ready

The press time and waste sheets spent bringing a job up to colour and register before good copies start. Fixed cost, unrelated to run length, and the main reason short runs cost so much per piece.

Forme

One side of one press sheet as imposed. A 16-page section printed both sides is two formes and, in 4 colours, eight plates.

Gang run

Several jobs imposed onto one press sheet so they share a single make-ready. Cheap, and only possible when the jobs share paper and colour set.

Imposition

The arrangement of pages on the press sheet so that, after printing, folding and trimming, they end up in reading order.

Bleed

Artwork extended 3 mm beyond the trim line so that a slight trimming variance does not leave a white edge.

Dot gain

The spread of a halftone dot as ink soaks into the sheet. High on uncoated stock, low on coated — which is why the same file looks different on the two.

Set-off

Wet ink transferring from one sheet onto the back of the sheet stacked above it. Caused by heavy coverage, coated stock and an impatient schedule.

Met-pet

Metallised polyester. Laminated to board or used as a label face to give a true metallic ground under the printing.

Wrapper

The printed cover sheet wrapped around a notebook block. Bought, printed and priced separately from the block, and a trade in its own right in Sivakasi.

Realart

Sivakasi trade term for a heavier art-paper calendar, usually 130 GSM at 20 × 30 in with full ink coverage.

Chutti, Super, Regular, Great, Giant, Day-Month, Mini

The seven Sivakasi calendar trade sizes. See the size table above for dimensions.

Panchangam sheet

A daily calendar leaf carrying almanac data — tithi, nakshatra, rahu kalam, yamagandam and muhurtham marks.

Centre-pinning

Stapling through the fold of a notebook or booklet. Reliable to about 200 pages, and not beyond.

Sectional-sewn

Signatures thread-sewn before being cased or glued in. The most durable binding available and the reason a good diary survives a year.