# Halftone Screen Printing: Gradients and Shading With One Screen

> How to print gradients and shading with a single screen: halftone dots from first principles, the mesh-to-LPI rule of thumb, moiré angles, and dot gain compensation on fabric.

**Source:** https://vectosolve.com/blog/halftone-screen-printing-gradients
**Author:** Robin Monteiro (Founder of VectoSolve)
**Published:** 2026-07-15
**Last updated:** 2026-07-15
**Category:** Tutorial
**Reading time:** 13 min read
**Tags:** screen printing, halftone, mesh count, dot gain, lpi, film positive

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Halftones start from clean art: if your source is still a raster file, run it through the [image to vector converter](/convert/image-to-vector) first.

## One screen is a binary device

Every point on a screen is either open or blocked. The stencil cannot do partial opacity: ink passes through open mesh at full strength or not at all. That is the fundamental constraint of the process, and it is why a smooth grayscale gradient sent straight to film comes back as a harsh edge between solid ink and bare fabric. The press has no way to lay down 40% ink.

Halftones solve this by trading resolution for tone. Break the image into a grid of cells, keep the grid spacing fixed, and vary only the size of the dot inside each cell. A region that should read as 20% gray gets small dots covering 20% of the cell area; a 70% region gets large dots covering 70%. Every individual dot is solid ink, which the press can print, and at viewing distance the eye averages dot and garment into an intermediate tone. Newspapers used the same trick for a century. Screen printers use it to put photographs, fades, and soft shading on shirts with one screen and one ink.

Dot frequency is measured in lines per inch (LPI): the number of dot rows per inch. At 45 LPI each cell is 1/45 of an inch across, about 0.022 in. Garment halftones are visibly dotted up close; at normal viewing distance they read as continuous tone, and the dot structure is part of the accepted look of the medium.

Dot shape matters less than frequency, but it matters. Round dots are the default; elliptical dots join their neighbors along one axis before the other as tones darken, which spreads the mid-tone jump over a wider range and prints smoother gradients. For a first halftone job, round or elliptical at a conservative LPI is the safe choice.

## Mesh count sets your LPI ceiling

The screen itself is a grid: threads woven at a count of 110, 156, 230, or more threads per inch. A halftone dot is not printed as a perfect circle; it is built from whichever mesh openings fall inside its outline. A dot spanning many openings reproduces well. A dot the size of a single opening is at the mercy of where it lands on the weave: over an opening it prints, over a thread it vanishes.

This is why LPI cannot be chosen independently of mesh. The working rule of thumb: **LPI at most mesh count divided by 4.5 to 5.**

Industry guidance converges on this ratio from both directions. ScreenPrinting.com's halftone crash course states the ideal LPI as the mesh count divided by 5 — a 160 mesh screen gives an ideal 32 LPI — and allows dividing by 4 instead (40 LPI on that same 160 mesh) only for shops with a dialed-in darkroom, according to ScreenPrinting.com. Chromaline, the stencil manufacturer, runs the arithmetic the other way: multiply the target LPI by 4.5 to find the lowest suitable mesh count, so 45 LPI calls for 45 × 4.5 = 202.5, with 195 or 200 being the closest real mesh (Chromaline). Chromaline adds a detail that rarely makes it into rules of thumb: tensioning elongates the mesh by 4 to 8%, so a 195 mesh pulled to 34 N/cm opens up to roughly 183 threads per inch on the frame. The count on the label is not the count you print through, and a mesh chosen with no margin can quietly fall below the ratio once stretched.

At that ratio, each halftone cell spans roughly 4.5 to 5 threads, which gives even small highlight dots enough mesh structure to anchor to. Run the numbers on a concrete case: a 10% dot at 45 LPI has a diameter of about 0.008 in (a circle covering 10% of a 0.022 in cell). On 230 mesh, threads are spaced 1/230 in apart, about 0.0043 in, so that 10% dot spans slightly less than two thread spacings, which is already marginal. Push the same art to 65 LPI on that mesh and the highlight dots shrink toward the size of a single opening and drop out while the shadow dots bridge together; the gradient collapses at both ends.

Saati's Tech Tips Handbook puts a hard number on that dropout threshold: the minimum detail you can cleanly and consistently print corresponds to a stencil opening equal to one mesh opening plus one and a half thread diameters. On a 305 plain-weave mesh with 34-micron threads that works out to dots of about 100 microns — a 3% dot on a 45-line halftone but already a 9% dot on an 85-line, and detail smaller than that, in Saati's words, "will always print as a moiré pattern." The same physical dot limit costs three times as much highlight range at the higher frequency.

| Mesh count (threads/in) | Conservative LPI (mesh / 5) | Upper bound (mesh / 4.5) | Typical use |
|---|---|---|---|
| 110 | 22 | 24 | Heavy ink deposit; halftones look coarse and bold |
| 156 | 31 | 34 | General garment work; a common halftone starting point |
| 200 | 40 | 44 | Finer detail with a thinner ink layer |
| 230 | 46 | 51 | Fine detail, softer hand feel |
| 305 | 61 | 67 | The fine end of garment printing |

Treat the table as a ceiling, not a target. Nothing stops you from running 35 LPI on a 305 mesh, and the print will be more forgiving for it: dots get bigger relative to the weave, exposure latitude improves, and dot gain hurts less. Coarse halftones fail gracefully; fine ones fail all at once.

Working guidance from the press-manufacturer side lands even more conservative than the table. Mark Coudray, of the Academy of Screen Printing Technology, writing in M&R's guide to printing halftones, recommends line counts around 40 to 50 LPI for garment work and says machine printing should rarely go over 55 LPI — paired with a 280 to 305 mesh in 34 to 35 micron thread, plain weave, which puts his mesh-to-LPI ratio closer to 6:1 than 5:1 (M&R Companies). He also specifies what the table leaves out: screen tension. His workable range is 25 ±2 N/cm, lower in a pinch but never below 20. Saati sets the same 20 N floor for four-color process printing and adds that all screens in a set should match within one to two newtons, or registration suffers (SaatiPrint Tech Tips Handbook). A loose screen moves under the squeegee, and a moving grid is one more moiré source that no angle change can fix.

## Moiré: why the angle is not zero

Lay two regular grids over each other and you get a third pattern that neither grid contains: interference bands, called moiré. In halftone screen printing at least two grids are in play on every job, the halftone dot grid and the mesh weave, and moiré between them shows up as wavy banding or a checkered shimmer across what should be a smooth gradient.

The weave runs at 0° and 90°. A halftone set at 0°, 45°, or 90° aligns with it in the worst way, drifting in and out of phase with the threads. The standard countermeasure for single-color halftone work is to rotate the dot grid to an angle with no simple relationship to the weave; 22.5° is the common choice, and nearby angles in the low-to-mid twenties work on the same principle. ScreenPrinting.com's halftone guide teaches the same figure and the mechanism behind it: at 22.5° the dots fall between the mesh threads rather than landing on threads or knuckles, while angles of 0°, 90°, 180°, or 270° line up with the threads and simply will not print, according to ScreenPrinting.com. (The 45° angle that is standard in offset lithography is a poor default here precisely because offset has no mesh to fight.)

The offset heritage is worth knowing because halftone software defaults often come from it. PrintWiki's screen-angles reference lists the standard four-color set as yellow at 0°, magenta at 15°, black at 45°, and cyan at 75°, built on the principle that moiré between two overlaid screens stays minimal when they sit 30° apart — a separation that cannot be given to all four inks, since four 30° separations would demand 120° and only 90° of distinct angles exist (PrintWiki). None of those angles were chosen with a mesh in the way. On a screen press the weave is the loudest grid in the stack, which is why single-color garment work converges on one weave-clearing angle instead of importing the offset set.

Angle alone does not make a job moiré-proof. Keeping the mesh-to-LPI ratio at 4.5:1 or higher does as much, because interference is strongest when the two frequencies are close. And the garment adds a third grid: knit fabric has its own repeating structure, which is one more reason coarse halftones on garments outlast fine ones. When moiré survives an angle change, drop the LPI before blaming the mesh.

## Dot gain: fabric makes everything darker

A halftone that looks correct on film prints darker on fabric. Squeegee pressure spreads the ink at the edge of every dot, and the fibers wick it further. This growth, called dot gain, is not uniform across the tonal range. It happens at dot perimeters, adding a ring of roughly constant width around each dot, so the tones with the most perimeter per unit area gain the most, and that peaks in the midtones around 50%. Highlights and shadows shift less; the middle of your gradient shifts a lot. A gradient built on a linear ramp comes off press with its midsection crushed toward black.

Two practical compensations:

1. **Clip the tonal range.** Dots below roughly 10% risk not anchoring to the mesh, and dots above roughly 85 to 90% gain their way into solid coverage. Treat both figures as rules of thumb that move with mesh, ink, and fabric. Saati's handbook tabulates exactly how they move: a 305 plain-weave 34-micron mesh safely holds 3% to 94% dots on a 45-line halftone but only 9% to 80% on an 85-line, and a job that has to hold a 10% to 85% tonal range at 85 LPI requires a 355 mesh or higher (SaatiPrint Tech Tips Handbook). The printable window narrows as frequency climbs; the coarser halftone is not just easier, it carries more of your gradient. Set the grayscale so printing tones stay inside that window, and let true white stay empty and true black stay solid.
2. **Lighten the midtones before halftoning.** Pull the 50% region of the grayscale down toward 35 to 40% with a curve adjustment. If that sounds aggressive, the manufacturer literature says it is not: Mark Coudray, in M&R's halftone guide, advises setting dot gain compensation for garment printing at a minimum of 38% and as high as 50%, noting he knows "very few screen printers that have less than 35% dot gain" — with gain always measured and added at the 50% tone (M&R Companies). Exactly how far to pull depends on your press, ink, and garment, which is why working shops keep a printed step wedge (tone patches from 5% to 95%) made on their own equipment and read the compensation off it instead of guessing.

On dark garments the logic inverts: you are often printing white or light ink, so gain makes the image lighter rather than darker, and the halftone is frequently printed over an underbase. The mechanics are identical; only the direction of the error flips.

## The workflow: art to film to screen

**1. Start from clean art at final size.** Halftoning is the last resolution-destroying step, so everything before it should be as clean as possible. If the source is a logo, a sketch, or a low-resolution raster, vectorize it first so edges are sharp and scaling costs nothing; the [screen print file converter](/c/screen-print-file-converter) handles this, and its watermarked preview is free with no signup; the clean file comes with a plan from $7.99/month. Scale the art to its printed dimensions before generating the halftone, never after. Resizing a finished halftone resamples the dots themselves and manufactures moiré out of nothing.

**2. Convert to grayscale and set the range.** Reduce the art to a single channel. Apply the range clip and the midtone compensation from the previous section. This is also the moment to decide what maps to bare fabric (no dots) and what maps to solid ink.

**3. Generate the halftone.** The [halftone generator](/halftone-generator) is free and runs in your browser: set the LPI from your mesh using the table above (the tool covers 5 to 60 LPI, so on 305 mesh its 60 maximum sits right at the conservative bound), set the angle to 22 or 23° (the slider moves in whole degrees, and anything in the low twenties clears the weave alignments), pick a dot shape, and export. Be clear about what it does not do: it produces the dot pattern, but it does not apply printer linearization or a dot gain curve calibrated to your press. The midtone compensation in step 2 stays your job, informed by your own step wedge.

**4. Output the film positive.** Print at exactly 100% scale onto film, with dots as opaque as your printer can make them. Semi-transparent dots under-expose the emulsion behind them and wash out unevenly. Check the film against a light source: highlight dots should be present with crisp edges, and shadow areas should show clear open film between dots.

**5. Expose, wash out, print.** Fine highlight dots are the first casualty of over-exposure and the first thing to rinse away under aggressive washout, which is one more argument for conservative LPI on early jobs.

For multi-color designs the halftone step simply repeats per ink. Split the art into one layer per spot color with the [SVG color separator](/svg-color-separator), which takes vector art apart by fill color. Note the limit: it separates flat spot colors from vector art; it is not a simulated-process separator for full-color photographs. Each separation then gets its own grayscale, its own halftone, and its own screen.

## FAQ

**What LPI should I use for T-shirts?**
Derive it from the mesh with the rule of thumb LPI at most mesh count divided by 4.5 to 5. On the common 156 mesh that means roughly 31 to 34 LPI; on 230 mesh, up to about 50. When in doubt, go coarser. A 35 LPI print that holds its full tonal range looks better than a 55 LPI print with blown highlights and plugged shadows.

**Can I really print a photo with one screen?**
Yes. Grayscale the photo, halftone it, and print it in one ink. At garment LPIs the result has a visible dot structure, closer to newsprint than to a lab print, and it works best on photos with strong tonal contrast. Low-contrast photos live entirely in the midtones, exactly where dot gain does the most damage.

**My gradient shows wavy bands on press. What went wrong?**
That is moiré. Check the halftone angle first (22.5° rather than 0°, 45°, or 90°), then the mesh-to-LPI ratio (raise the mesh or lower the LPI until the ratio is at least 4.5:1). If the banding tracks the fabric texture rather than the mesh, the knit itself is interfering, and the fix is the same: coarser dots.

**Do I halftone before or after resizing the art?**
After all resizing is finished, always. A halftone is a fixed physical pattern: dots of specific sizes at a specific frequency. Scaling it changes the effective LPI and resampling distorts the dots. Set final print dimensions, then generate the halftone as the last step before film output.

## Sources

- [ScreenPrinting.com (Ryonet) — A Crash Course in Halftones for Screen Printing](https://www.screenprinting.com/blogs/news/a-crash-course-in-halftones-for-screen-printing) — the mesh-count-divided-by-5 LPI rule (divided by 4 for dialed-in darkrooms) and the 22.5° halftone angle convention with the thread-alignment warning.
- [Chromaline — Harmonizing Mesh Count to Line Count](https://chromaline.com/harmonizing-mesh-count-to-line-count/) — the LPI × 4.5 minimum-mesh multiplier and mesh elongation under tension (4 to 8%; 195 mesh at 34 N/cm opening to ~183 threads per inch).
- [M&R Companies — Quick Start Secrets to Printing Better Halftones, by Mark A. Coudray (PDF)](https://www.mrprint.com/files/top-ten-secrets-v3-9r6BVM00r20144yr.pdf) — garment line counts (40 to 50 LPI, rarely over 55), mesh and thread spec (280 to 305 mesh, 34 to 35 micron plain weave), working tension (25 ±2 N/cm, never below 20), and dot gain compensation figures (38% minimum, up to 50%, measured at the 50% tone).
- [SaatiPrint Tech Tips Handbook (PDF)](https://www.catspitproductionsllc.com/Documents/SaatiPrint%20TechTip%20Handbook.pdf) — the minimum printable dot rule (one mesh opening plus one and a half thread diameters), printable tonal ranges per mesh and LPI (305.34 PW: 3 to 94% at 45 LPI vs 9 to 80% at 85 LPI), and process-work tension guidance (20 N floor, screens matched within 1 to 2 N).
- [PrintWiki — Screen Angles](https://printwiki.org/Screen_Angles) — the standard four-color offset screen angles (yellow 0°, magenta 15°, black 45°, cyan 75°) and the 30° separation rule.

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*Maintained by VectoSolve. When citing, link to https://vectosolve.com/blog/halftone-screen-printing-gradients.*

*VectoSolve — AI-powered SVG platform: image-to-vector conversion, AI animation, brand identity generation, and more. https://vectosolve.com*