{"course":{"slug":"vector-and-print","title":"Vectors, Logos and Things That Get Printed","url":"https://addaly.com/learn/vector-and-print","level":"beginner","track":"create"},"lesson":{"slug":"halftones-and-dot-gain","title":"Why your 20% tint printed at 30%","url":"https://addaly.com/learn/vector-and-print/halftones-and-dot-gain","position":31,"of":73,"minutes":9,"answer":"Tone is made of dots, and a dot grows when it hits paper (around 15% on coated and 25% on uncoated at the midtone) which the press profile already corrects for.","keyIdea":"Tone is made of dots, and a dot grows when it hits paper (around 15% on coated and 25% on uncoated at the midtone) which the press profile already corrects for, so the failures come from converting with the wrong profile or from relying on very light tints and small reversed type."},"body":{"format":"markdown","text":"## Ink is one density; tone is an illusion\n\nA press lays down ink at full strength or not at all. There is no such thing as 30% cyan ink. A 30% tint is a field of tiny cyan dots covering 30% of the area, and your eye averages them.\n\nThat conversion (continuous tone into a pattern of dots) is **screening**, and the RIP does it.\n\n## AM screening, the traditional kind\n\n**Amplitude modulated** screening puts dots on a regular grid at a fixed spacing and varies their *size*. The spacing is the **line screen**, measured in lines per inch:\n\n- Newsprint: **85 lpi**\n- Uncoated stock, general commercial: **133 lpi**\n- Coated stock, quality commercial: **150 to 175 lpi**\n- Fine art and packaging: **200 lpi and above**\n- Screen printing on textile: **35 to 65 lpi**, because the mesh cannot hold finer\n- Large format outdoor: as low as **15 to 25 lpi**, seen from distance\n\nEach of the four inks is screened at a **different angle** so the dots do not sit on top of each other. The conventional set is cyan 15°, magenta 75°, yellow 0°, black 45°: black at 45° because a diagonal pattern is least visible to the eye, and yellow at 0° because it is the palest and its pattern shows least.\n\nGet the angles wrong and you get **moiré**: a coarse interference pattern from two fine patterns overlapping. Get them right and you get a **rosette**, the tiny flower shape you can see with a loupe on any printed photograph.\n\nMoiré also appears when your *artwork* contains a fine regular pattern (a scanned halftone, a fabric weave, a pinstripe) that interferes with the press screen. The fix is to blur the artwork very slightly or change its scale, and it must be done before the RIP sees it.\n\n## FM screening\n\n**Frequency modulated** or stochastic screening uses dots of one small size scattered pseudo-randomly, varying their *number*. No grid, so no angles and no moiré at all, and much finer detail. It demands better press control and it dries differently. Increasingly common on good digital and offset work; ask whether your shop offers it if the job has a scanned pattern in it.\n\n## Dot gain, and the number you need\n\nA dot printed on paper comes out bigger than the dot on the plate. Two separate mechanisms:\n\n- **Mechanical gain.** Ink physically spreads as it is pressed into the paper. Worse on absorbent, uncoated stock.\n- **Optical gain.** Light enters the paper beside a dot, scatters, and emerges under it. The dot *appears* larger than it is even when it is not.\n\nTogether they are substantial. Typical midtone (50%) gain:\n\n- Coated sheetfed offset: **13 to 17%**, so a 50% tint reads as about 64%\n- Uncoated: **20 to 25%**: a 50% tint reads as about 72%\n- Newsprint: **25 to 30%**\n- Screen print on textile: **can exceed 30%**\n\n**The press profile already accounts for this.** Convert with FOGRA51 for coated or FOGRA52 for uncoated and the numbers going to the plate are adjusted so the printed result is right. Dot gain becomes a problem when you *do not* use a profile, or when you use the wrong one: an uncoated job converted with a coated profile prints visibly dark and muddy.\n\n> Figure: What the paper does to a tint. Line chart of Tint measured on the sheet, per cent against Tint in the file, per cent: Uncoated, about 25% at the midtone (0, 0) (10, 21) (25, 44) (50, 72) (75, 91) (100, 100); Coated, about 15% (0, 0) (10, 16) (25, 36) (50, 64) (75, 86) (100, 100). The press profile already corrects for this, so the trouble comes from converting with the wrong one. An uncoated job converted with a coated profile prints dark and muddy across every midtone in it.\n\n## What to do about it in your artwork\n\nThree practical consequences you control directly.\n\n**Light tints close up.** A 5% tint on uncoated can print at 12% or vanish entirely depending on the press's minimum dot. If a design depends on a very pale wash, print a test or use a heavier tint of a lighter colour.\n\n**Small reversed type fills in.** White text on a dark ground loses width as ink spreads into the counters. Below about 8 pt in a light weight on uncoated stock, an `e` closes up. Use a heavier weight, a larger size, or accept it.\n\n**Fine screens in artwork clash.** Avoid pinstripes below about 0.3 mm pitch in anything going to litho.\n\n## The check that costs nothing\n\nAsk the printer for a printed **tint chart** on the stock you are using: a grid of 5% steps in each ink and in common builds. Many shops have one and will hand it over. It is the single most useful object in the trade: it tells you exactly what 20% cyan looks like on that paper, on that press, with no screen involved in the decision."},"check":{"question":"A brochure designed with a delicate 5% grey background wash is proofed on a coated digital printer and looks right. The production run is on uncoated stock and the wash prints as a distinctly visible grey. Nothing was changed in the file. Why?","options":[{"text":"The uncoated run used FM screening, which distributes dots randomly and increases apparent coverage at low percentages.","correct":false,"tempting":"FM screening changes dot placement, not total coverage, and it is generally chosen to improve fidelity rather than to darken light tints."},{"text":"Uncoated stock is less bright, so the same ink coverage reads darker against a duller paper white.","correct":false,"tempting":"Paper brightness contributes a little, but a 5% tint becoming clearly visible is an ink-coverage effect, not a substrate-brightness effect."},{"text":"The digital proof rendered the 5% as a continuous tone while the offset press screened it into dots, which always look darker.","correct":false,"tempting":"Screening does not inherently darken. A correctly profiled screened tint matches its continuous-tone equivalent."},{"text":"Dot gain on uncoated stock runs around 25% at the midtone, so a 5% tint prints as considerably more.","correct":true}]},"prev":{"slug":"gamut-and-rendering-intents","title":"What happens to a colour the press cannot print","url":"https://addaly.com/learn/vector-and-print/gamut-and-rendering-intents"},"next":{"slug":"spot-colours-and-plates","title":"A spot colour is a plate, and a plate is money","url":"https://addaly.com/learn/vector-and-print/spot-colours-and-plates"},"authorship":"Founder and series editor: Dr Mustafa Mun. Written by AI models to a written standard. Exam keys checked blind by a second model: 3,665 of 3,666 agreed. Academic review invited.","review":{"status":"Draft, open for academic review"},"cite":"Addaly (2026) 'Why your 20% tint printed at 30%', in Vectors, Logos and Things That Get Printed. Edited by M. Mun. Addaly. Available at: https://addaly.com/learn/vector-and-print/halftones-and-dot-gain (Accessed: 13 October 2026).","licence":{"name":"CC BY-NC-SA 4.0","url":"https://creativecommons.org/licenses/by-nc-sa/4.0/"},"reader":{"schema":1,"title":"Why your 20% tint printed at 30%","courseTitle":"Vectors, Logos and Things That Get Printed","module":{"index":4,"slug":"colour-for-print","title":"Colour that survives the press"},"answer":null,"keyIdea":"Tone is made of dots, and a dot grows when it hits paper (around 15% on coated and 25% on uncoated at the midtone) which the press profile already corrects for, so the failures come from converting with the wrong profile or from relying on very light tints and small reversed type.","hero":{"kind":"figure","figure":{"t":"figure","label":"Figure","figure":{"type":"line","title":"What the paper does to a tint","series":[{"label":"Uncoated, about 25% at the midtone","points":[[0,0],[10,21],[25,44],[50,72],[75,91],[100,100]]},{"label":"Coated, about 15%","points":[[0,0],[10,16],[25,36],[50,64],[75,86],[100,100]]}],"xLabel":"Tint in the file, per cent","yLabel":"Tint measured on the sheet, per cent","caption":"The press profile already corrects for this, so the trouble comes from converting with the wrong one. An uncoated job converted with a coated profile prints dark and muddy across every midtone in it."},"alt":"Figure: What the paper does to a tint. Line chart of Tint measured on the sheet, per cent against Tint in the file, per cent: Uncoated, about 25% at the midtone (0, 0) (10, 21) (25, 44) (50, 72) (75, 91) (100, 100); Coated, about 15% (0, 0) (10, 16) (25, 36) (50, 64) (75, 86) (100, 100). The press profile already corrects for this, so the trouble comes from converting with the wrong one. An uncoated job converted with a coated profile prints dark and muddy across every midtone in it."}},"blocks":[{"t":"h2","id":"ink-is-one-density-tone-is-an-illusion","runs":[{"text":"Ink is one density; tone is an illusion"}]},{"t":"p","runs":[{"text":"A press lays down ink at full strength or not at all. There is no such thing as 30% cyan ink. A 30% tint is a field of tiny cyan dots covering 30% of the area, and your eye averages them."}]},{"t":"p","runs":[{"text":"That conversion (continuous tone into a pattern of dots) is "},{"text":"screening","b":true},{"text":", and the RIP does it."}]},{"t":"h2","id":"am-screening-the-traditional-kind","runs":[{"text":"AM screening, the traditional kind"}]},{"t":"p","runs":[{"text":"Amplitude modulated","b":true},{"text":" screening puts dots on a regular grid at a fixed spacing and varies their "},{"text":"size","i":true},{"text":". The spacing is the "},{"text":"line screen","b":true},{"text":", measured in lines per inch:"}]},{"t":"ul","items":[[{"text":"Newsprint: "},{"text":"85 lpi","b":true}],[{"text":"Uncoated stock, general commercial: "},{"text":"133 lpi","b":true}],[{"text":"Coated stock, quality commercial: "},{"text":"150 to 175 lpi","b":true}],[{"text":"Fine art and packaging: "},{"text":"200 lpi and above","b":true}],[{"text":"Screen printing on textile: "},{"text":"35 to 65 lpi","b":true},{"text":", because the mesh cannot hold finer"}],[{"text":"Large format outdoor: as low as "},{"text":"15 to 25 lpi","b":true},{"text":", seen from distance"}]]},{"t":"p","runs":[{"text":"Each of the four inks is screened at a "},{"text":"different angle","b":true},{"text":" so the dots do not sit on top of each other. The conventional set is cyan 15°, magenta 75°, yellow 0°, black 45°: black at 45° because a diagonal pattern is least visible to the eye, and yellow at 0° because it is the palest and its pattern shows least."}]},{"t":"p","runs":[{"text":"Get the angles wrong and you get "},{"text":"moiré","b":true},{"text":": a coarse interference pattern from two fine patterns overlapping. Get them right and you get a "},{"text":"rosette","b":true},{"text":", the tiny flower shape you can see with a loupe on any printed photograph."}]},{"t":"p","runs":[{"text":"Moiré also appears when your "},{"text":"artwork","i":true},{"text":" contains a fine regular pattern (a scanned halftone, a fabric weave, a pinstripe) that interferes with the press screen. The fix is to blur the artwork very slightly or change its scale, and it must be done before the RIP sees it."}]},{"t":"h2","id":"fm-screening","runs":[{"text":"FM screening"}]},{"t":"p","runs":[{"text":"Frequency modulated","b":true},{"text":" or stochastic screening uses dots of one small size scattered pseudo-randomly, varying their "},{"text":"number","i":true},{"text":". No grid, so no angles and no moiré at all, and much finer detail. It demands better press control and it dries differently. Increasingly common on good digital and offset work; ask whether your shop offers it if the job has a scanned pattern in it."}]},{"t":"h2","id":"dot-gain-and-the-number-you-need","runs":[{"text":"Dot gain, and the number you need"}]},{"t":"p","runs":[{"text":"A dot printed on paper comes out bigger than the dot on the plate. Two separate mechanisms:"}]},{"t":"ul","items":[[{"text":"Mechanical gain.","b":true},{"text":" Ink physically spreads as it is pressed into the paper. Worse on absorbent, uncoated stock."}],[{"text":"Optical gain.","b":true},{"text":" Light enters the paper beside a dot, scatters, and emerges under it. The dot "},{"text":"appears","i":true},{"text":" larger than it is even when it is not."}]]},{"t":"p","runs":[{"text":"Together they are substantial. Typical midtone (50%) gain:"}]},{"t":"ul","items":[[{"text":"Coated sheetfed offset: "},{"text":"13 to 17%","b":true},{"text":", so a 50% tint reads as about 64%"}],[{"text":"Uncoated: "},{"text":"20 to 25%","b":true},{"text":": a 50% tint reads as about 72%"}],[{"text":"Newsprint: "},{"text":"25 to 30%","b":true}],[{"text":"Screen print on textile: "},{"text":"can exceed 30%","b":true}]]},{"t":"p","runs":[{"text":"The press profile already accounts for this.","b":true},{"text":" Convert with FOGRA51 for coated or FOGRA52 for uncoated and the numbers going to the plate are adjusted so the printed result is right. Dot gain becomes a problem when you "},{"text":"do not","i":true},{"text":" use a profile, or when you use the wrong one: an uncoated job converted with a coated profile prints visibly dark and muddy."}]},{"t":"h2","id":"what-to-do-about-it-in-your-artwork","runs":[{"text":"What to do about it in your artwork"}]},{"t":"p","runs":[{"text":"Three practical consequences you control directly."}]},{"t":"p","runs":[{"text":"Light tints close up.","b":true},{"text":" A 5% tint on uncoated can print at 12% or vanish entirely depending on the press’s minimum dot. If a design depends on a very pale wash, print a test or use a heavier tint of a lighter colour."}]},{"t":"p","runs":[{"text":"Small reversed type fills in.","b":true},{"text":" White text on a dark ground loses width as ink spreads into the counters. Below about 8 pt in a light weight on uncoated stock, an "},{"text":"e","code":true},{"text":" closes up. Use a heavier weight, a larger size, or accept it."}]},{"t":"p","runs":[{"text":"Fine screens in artwork clash.","b":true},{"text":" Avoid pinstripes below about 0.3 mm pitch in anything going to litho."}]},{"t":"h2","id":"the-check-that-costs-nothing","runs":[{"text":"The check that costs nothing"}]},{"t":"p","runs":[{"text":"Ask the printer for a printed "},{"text":"tint chart","b":true},{"text":" on the stock you are using: a grid of 5% steps in each ink and in common builds. Many shops have one and will hand it over. It is the single most useful object in the trade: it tells you exactly what 20% cyan looks like on that paper, on that press, with no screen involved in the decision."}]}],"check":{"question":[{"text":"A brochure designed with a delicate 5% grey background wash is proofed on a coated digital printer and looks right. The production run is on uncoated stock and the wash prints as a distinctly visible grey. Nothing was changed in the file. Why?"}],"options":[{"text":[{"text":"The uncoated run used FM screening, which distributes dots randomly and increases apparent coverage at low percentages."}],"correct":false,"tempting":[{"text":"FM screening changes dot placement, not total coverage, and it is generally chosen to improve fidelity rather than to darken light tints."}]},{"text":[{"text":"Uncoated stock is less bright, so the same ink coverage reads darker against a duller paper white."}],"correct":false,"tempting":[{"text":"Paper brightness contributes a little, but a 5% tint becoming clearly visible is an ink-coverage effect, not a substrate-brightness effect."}]},{"text":[{"text":"The digital proof rendered the 5% as a continuous tone while the offset press screened it into dots, which always look darker."}],"correct":false,"tempting":[{"text":"Screening does not inherently darken. A correctly profiled screened tint matches its continuous-tone equivalent."}]},{"text":[{"text":"Dot gain on uncoated stock runs around 25% at the midtone, so a 5% tint prints as considerably more."}],"correct":true,"tempting":null}],"order":[1,2,0,3],"why":null},"prev":{"slug":"gamut-and-rendering-intents","title":"What happens to a colour the press cannot print","minutes":8},"next":{"slug":"spot-colours-and-plates","title":"A spot colour is a plate, and a plate is money","minutes":9}}}