Process · Screen printing
Screen printing colour separation that aims at the inks you actually mixed.
Set the hue of each extended ink to the one in your bucket, then export a positive halftone film — spot separations (Sanguine) or halftoned CMYK, with registration marks. And measure your own dot gain: exposure and ink spread through your mesh, not a chart average.
Reviewed by Tristan Sidem + Raphaël Lebas de Lacour
Le problème
Sound familiar?
- 01
Highlights disappear at exposure
Small halftone dots that were supposed to hold the lightest tones do not harden the emulsion enough — they wash out at rinsing, and the print comes out with no highlights at all.
- 02
Midtones plug up on the print
Ink spreads through the mesh beyond the open dot. A 50% dot on the film can cover 65-75% on the shirt or the paper — differently in every workshop, since it depends on your mesh, ink and pressure.
- 03
Moiré between colours in a halftoned job
Every film comes out at the same screen angle. Overlay two or three halftoned separations and an interference pattern can appear where traditional prepress would have rotated each angle.
The difference on a screen print
The same source file, printed without calibration on the left and calibrated with Calibration Flow on the right. You can see how calibration frees the full tonal range of your screen process.
Spécificités du procédé
A positive film, a mesh that sets the ceiling, and ink that spreads.
Screen printing is not an alternative photo process — it is frame printing: a silk (or polyester) mesh screen, coated with a photosensitive emulsion, exposed under a film, then rinsed and squeegeed with ink. That changes the first rule you have to unlearn coming from cyanotype or Van Dyke: the film is a positive, not a negative. The emulsion hardens where light passes; the film must be opaque wherever you want ink.
A screen only knows two states — ink passes, or it does not — so tonal gradation has to become dots of variable size: a classic AM halftone, angled screen, with an automatic Floyd-Steinberg error-diffusion fallback when the configuration suits it poorly. Frequency follows export resolution (300 dpi ≈ 50 lpi, 400 ≈ 67, 500 ≈ 83) and must respect the mesh: lpi ≤ threads per inch ÷ 4-5. Fine paper/poster meshes (≥ 90 threads/cm) are comfortable at 50 lpi; coarse textile meshes (43-55 threads/cm) push you towards flat spot colours or error diffusion instead.
Multi-colour separation has two regimes. Sanguine splits the tonal range into 2-3 spot films by band, with a reconstitution check and a share slider — the most common setup in craft screen printing. Halftoned CMYK goes up to 4 films (7 inks in Full Gamut), but every film shares the same screen angle: a real moiré risk in a halftoned quadri job that traditional prepress avoids by rotating each angle, which this tool does not do. Registration uses printed targets with an orientation key.
What calibration actually fixes is dot gain: the tonal drift from exposure and ink spread through the mesh, specific to your mesh + emulsion + ink + squeegee pressure. Print a 25-patch target under your real conditions, photograph it, and the measured curve compensates it — recalibrate at every change of mesh, ink, emulsion or press. It does not fix mechanical defects: an unevenly tensioned screen or uneven exposure still needs a stable process before you calibrate on top of it.
Target polarity: positive — the one process on this site where that is true.
Lire en détail dans le manuel
Référence externe : Wikipedia
Custom inks
You mix your own inks. The separation should aim at those.
A screen printer rarely prints a catalogue orange: you mix it, on the bench, for that job. Every RIP separates towards a fixed, assumed ink set — so the file aims at an orange that is not in your bucket, and the overlap lands somewhere else. Here you set the hue of each extended ink to the one you actually mixed, and the separation is recomputed for that ink.
Reference inks — the starting point, not an obligation.
Honest limits: three extended inks are adjustable in hue (orange, green, violet), each within the range shown above — not an arbitrary Pantone. The setting is deliberately not remembered between sessions: your ink changes from batch to batch, and a stale saved hue would silently separate towards last month's mix.
Screen angles
Every film comes out at its own angle. As in prepress.
A halftone is a grid of dots. Two grids laid at the same angle put their dots in exactly the same place: each ink covers the previous one as much as it can, the colour is as dark as the ink laid down allows, and the slightest frame misregistration shows as a fringe. Rotating each film to a different angle is the rosette — the basic gesture of screen-printing prepress.
A round-dot screen repeats every 90°, so there are three safe slots 30° apart for the strong inks, with yellow at 0°. Seven inks for four slots: each extended ink takes the angle of its complement — the one that is absent where it is laid. The separation engine guarantees it: a saturated orange contains no cyan, and in the greys, where cyan, magenta and yellow work together, the extended inks are zero.
| Ink | Angle | Why |
|---|---|---|
| Yellow | 0° | The lightest ink: its moiré is invisible. It takes the worst angle. |
| Cyan | 15° | A strong ink, 30° from black. |
| Black | 45° | The angle where the eye detects a pattern least. In Aquaprint it goes on second, opaque, over dry ink. |
| Magenta | 75° | A strong ink, 30° from black on the other side. |
| Orange | 15° | Same angle as cyan — where orange is laid, cyan is absent. |
| Green | 75° | Same angle as magenta — its absent one. |
| Violet | 0° | Same angle as yellow — its absent one. |
| Single film | 54° | Negative, positive, ink steps, target: a single film, nothing to spread apart. The historical angle, which avoids running parallel to the mesh threads. |
Transparent inks
Aquaprint, process inks: the overlap IS the colour.
A yellow under a cyan makes a green because light goes through both. The rosette makes that overlap regular and tolerant to registration; the total ink amount stays the engine’s. It is the app’s default screening; in the colour negative, the Effects tab keeps under “Screen” a “Screen angles: One per ink / Aligned” selector so you can compare both on your press.
Opaque inks
Plastisol, opaque inks: each layer hides the one below.
There, stacking no longer mixes: an opaque cyan over a yellow makes a cyan. Colours have to form in the eye, side by side. That is not a screened-separation case: with opaque inks you print flat colours, one plate per colour, and the app has no “opaque inks” setting — the process inks of a four-colour job are transparent by design.
Honest limits: the angles are those of the table, not adjustable film by film — and no angle is safe for every mesh, mesh/halftone moiré is checked on a test strip. Halftone fineness follows the export resolution (300, 450, 600 dpi → 50, 75, 100 lpi): choosing an lpi from the mesh count is a separate piece of work, not shipped yet.
Generate your screen printing target now
25-patch target (5×5 grid + continuous gradient), equal steps of about 4.2 % in grey value, from white to black. Positive polarity (matches this process). Download, print on inkjet transparency with colour management off, expose onto your sensitised paper.
Round dot, screen rotated to 54° — the screen-printing rendering of a single film. Use it if you print halftoned films: measuring dot gain on a continuous-tone target measures something other than what you print.
Downloaded file at 1680×1410 px (300 dpi), free, no sign-up. In the app, a 25-step grey grid and its gradient print straight onto a corner of your negative (Target → Show the target tab) and get the same curve as the image.
Target computed like the app’s: evenly spaced grey steps and a continuous gradient, then AM halftone with a round dot, 54° screen, 50 lpi at 300 dpi — the same halftoner as the app, with its 6-dot minimum cell. 54° is the single-film angle; in colour, the app rotates each film to its own angle (rosette). On a scan, the app reads each step as perceptual lightness, L* (CIELAB).
Workflow en 3 étapes
Mire, insolation, courbe.
Generate the halftoned positive film (or separations)
Positive mode, Dither halftone on (AM screen, error-diffusion fallback if needed). Sanguine for 2-3 spot inks, CMYK for a halftoned quadri job.
Expose the screen, print the 25-patch target
Coat the emulsion, expose, rinse, dry. Print the target under your real conditions: your mesh, your ink, your squeegee pressure, your substrate.
Photograph, measure, export the .acv curve (Pro Mode)
The app reads the real value of each patch and builds the dot-gain compensation curve, applied to every film you export afterwards. .acv export is reserved for Pro mode (€9.90/month).
Adjust the curve live
Calibration Flow corrects any non-linear response with three sliders. No point to draw with the mouse, no Bézier handle to wrangle. Play with the values below and see the effect on the curve and on the screen printing tonal rendering immediately.
Input 0–255 ↔ Output 0–255
Minimum input threshold. Everything below it becomes pure black.
Maximum input threshold. Everything above it becomes pure white.
Midtone curvature. 1.00 = linear, < 1 = darker mid-tones, > 1 = lighter mid-tones.
Source gradient (before correction)
Corrected gradient (after applying the curve)
This demo applies a simple formula (black/white points + gamma exponent) for illustration. The app additionally uses a robust LOWESS + monotone PCHIP smoothing pass that rounds off transitions without creating artefacts. The Mode Pro (€9.90/month) then lets you export a .acv file, loadable into Photoshop or Affinity Photo in two clicks.
Preuve d'autorité
Pourquoi nous faire confiance.
« Screen printing is the process that reverses the rule every alt-process photographer learns first: the film is positive, not negative. Beyond that inversion, the real work is the same — measure what your own screen, ink and squeegee actually do to a tonal step, and correct exactly that. Not a chart average, your own dot gain. »
Références techniques
- Wikipedia — Screen printing (mesh, emulsion, squeegee mechanics)
- Wikipedia — Dot gain (halftone dot growth at exposure and printing)
- Calibration Flow manual — Making a screen printing halftone film, Halftone frequency and screen mesh, Calibrating dot gain
Signé
- Tristan Sidem — founder of Calibration Flow + Vision Picturale
- Raphaël Lebas de Lacour — co-founder of Vision Picturale
Access & pricing
Try Calibration Flow.
Web
Free with account
- 3 curves, unlimited presets, 10 HD scans, 300 MB storage
- No credit card required
Pro · Web + iOS
€9.90/month
- .acv export for Photoshop/Lightroom
- HD Full Gamut export (5-7 inks) & advanced separation settings
- 100 HD scans, 5 GB cloud storage
- One subscription for Web + iOS, cancel anytime
Code Luminograph
1 year of Pro included
- Shipped with the purchase of a Luminograph at Vision Picturale
- One year of Pro mode, then reverts to free
- Extended quotas and 5 GB of cloud storage
Honest comparison
Against the tools screen printers actually compare.
| Dimension | Calibration Flow | Wasatch SoftRIP | AccuRIP + Sep Studio | Manual, in Photoshop |
|---|---|---|---|---|
| Separates towards YOUR mixed inks | Hue of the 3 extended inks is adjustable | Fixed ink set from the profile | Chosen spot inks, catalogue hues | By hand, layer by layer |
| Dot gain measured on your own press | 25-patch target, photographed | Curves you enter yourself | Curves you enter yourself | Estimated by eye |
| Per-colour screen angle (anti-moiré) | No | Yes | Yes | Yes |
| Positive halftone film output | Native, in the browser | Native | Native | Manual |
| Platform | Browser + iPhone | Windows | Windows / macOS | Photoshop required |
| Entry price | €0 — free with an account | $569/year (or $49/month) | $399/year (bundle) | Adobe subscription |
Competitor prices read from public vendor pages, September 2026 — check before you buy.
When to choose one of the others
For a large halftoned CMYK production run, a dedicated screen-printing RIP still wins: it rotates the screen angle per colour, which is the classic defence against moiré, and Calibration Flow does not. Separation Studio also goes further on simulated-process separations with many spot inks. Calibration Flow owns the step neither of them does — aiming the separation at the ink you mixed this morning, and measuring the dot gain your own press actually produces.
FAQ
Questions from screen printers.
- Yes, for the three extended inks. Beyond cyan, magenta, yellow and black, Calibration Flow can output up to three more films — orange, green, violet — and you set the HUE of each one to the ink actually in your bucket, with a slider. The separation is then recomputed for those inks. No RIP does this: they separate towards a fixed ink set, assuming a catalogue orange you do not have on the bench. Two honest limits: each ink is adjustable within a hue range (an orange stays an orange — this is not an arbitrary Pantone), and the setting is deliberately not remembered between sessions, because your mix changes and a stale saved hue would silently separate towards last month's ink.
- Positive, always. That is the opposite of contact-exposure photo processes (cyanotype, Van Dyke, platinum/palladium), which need a negative target. In screen printing, the photosensitive emulsion hardens where light passes through, so the film must be opaque wherever you want ink. In Calibration Flow, pick Positive mode (Type tab) — the rest of the workflow (halftone, registration, calibration) does not change.
- The workshop rule: lpi ≤ threads per inch ÷ 4 to 5. In Calibration Flow, the halftone frequency follows export resolution — 300 dpi ≈ 50 lpi, 400 dpi ≈ 67 lpi, 500 dpi ≈ 83 lpi. A fine mesh (≥ 90 threads/cm, paper or poster work) is comfortable at 300 dpi. A coarse textile mesh (43 to 55 threads/cm) makes a 50 lpi AM halftone risky — prefer flat spot colours (Sanguine) or test the error-diffusion fallback on a strip before a run.
- That is what Sanguine does: it splits the tonal range into 2 or 3 spot films, one per band, each with its own exposure rank and a reconstitution check that verifies the overlay rebuilds the image before export. The share slider sets your tolerance to registration drift. It is the most common setup in craft screen printing — and it avoids the moiré risk of a halftoned CMYK job, since each ink carries a different tonal band rather than the same overlaid screen.
- Yes, up to 4 films (and 7 inks in Full Gamut). Each film comes out at its own screen angle, as in screen-printing prepress: yellow 0°, cyan 15°, black 45°, magenta 75°, and each extended ink takes its complement's angle. That keeps the dots of each ink from landing in the same place — but no angle is safe for every mesh: test before a production run. For 2-3 colours, Sanguine stays the safer choice.
- A halftone dot grows twice over: at exposure (small dots do not always harden cleanly) and at printing (ink spreads through the mesh). A 50% dot on the film can end up covering 65-75% on the print, and how much depends on YOUR screen, YOUR emulsion, YOUR ink and YOUR squeegee pressure — no standard value predicts it. Calibration Flow measures it: you print a 25-patch target under your real conditions, photograph it, and the app builds the compensation curve applied to every following film. Recalibrate whenever mesh, ink, emulsion or press changes — the curve compensates tonal drift, not mechanical defects (an unevenly tensioned screen, uneven exposure).
Screen printing is not an alt-process photo technique — it is frame printing.
The Picturale ecosystem's six UV-exposure processes — cyanotype, gum bichromate, carbon, bromoil, gumoil, resinotype — all print by contact exposure onto a light-sensitised surface, negative film against paper. Screen printing works the opposite way: a positive film exposes a stencil on a mesh screen, then ink is pushed through by hand with a squeegee. Calibration Flow calibrates it the same way regardless: you print a target under your real conditions, scan it, measure it, export a .acv curve (Pro mode, €9.90/month).
A few references if you are starting screen printing:
- Screens and emulsion — mesh count is given in threads/cm (Europe) or threads/inch; photosensitive emulsions and diazo/photopolymer sensitisers are sold by most screen-printing suppliers (Fimor, Sun Chemical, MacDermid) with their own exposure-time charts as a starting point.
- Ink — water-based inks (textile, more environmentally benign, heat-cured) and plastisol inks (opaque, does not dry in the screen, also heat-cured) behave differently for dot gain and mesh choice; this tool does not measure or distinguish between them, only the tonal result on your print.
- Registration — printed registration targets with an orientation key help align 2-4 colours by eye; a mechanical registration jig remains the reference for production runs.
- Reading — Wikipedia's Screen printing and Dot gain entries cover the underlying mechanics referenced above.
- Calibration — open Calibration Flow, follow the step-by-step. Positive film, target print, scan, measurement,
.acvcurve (Pro mode) — the same workflow as for a cyanotype, just a positive film and a mesh instead of a negative and paper.
Do you also practise a Vision Picturale process in parallel (cyanotype, gum bichromate, carbon…)? See the six ecosystem processes →
Measure your dot gain before your next production run.
Free with registration on the Web version: target, curve and negative included, no credit card required. Pro Mode (€9.90/month) adds .acv export and extended quotas.
Try it free — no credit card