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Screen printing: moire, white underbase, LPI.

Screen printing moire, white underbase and halftones: 300 DPI raster, 1 pt strokes, 2 pt gaps, 46 to 55 LPI: what printers and RIPs ask of a file.

Sources read 2026-10-21 · updated 2026-10-26 · next re-read due 2027-01-19

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How the process treats your file

Screen printing pushes ink through a mesh stencil, one screen per colour (Custom Ink: image resolution guide). Flat art goes in as vector, listed as .ai, .eps or .svg in Custom Ink’s screen-printing row (Custom Ink), with every colour set as a 100% spot swatch (Freehand: AccuRIP Emerald halftones). The floors read are 1 pt strokes and 6 pt text (Custom Ink), 8 pt text (Oregon Screen Impressions) and 2 pt negative gaps (Print Your Cause).

Photographs and gradients take a second path. A separation RIP or a Photoshop workflow splits the art into channels, and the RIP outputs film positives at a chosen halftone frequency in LPI (CADlink: separations and halftones). The UltraSeps sheet sets 55 or 60 LPI for CMYK separations (UltraSeps film output); AccuRIP Emerald defaults to 30 LPI (Freehand: AccuRIP halftone settings). Mesh follows the frequency: AccuRIP says 5x, so 46 LPI means 230 mesh (Freehand: Don’t Fear Halftones), and Chromaline’s rule of thumb is 4.5x (Chromaline).

On dark garments the white underbase is flash cured before the top colours print (Anatol). It is choked inward: 0.05 pt by default in Separation Studio NXT (Freehand: base choke), up to 2 pt (Freehand: base generation), or 1, 2 or 3 pixels in UltraSeps (UltraSeps user guide).

What the printers specify

Two sources give sizes: Custom Ink’s per-garment table, which covers all decoration methods (Custom Ink), and Print Your Cause, which scales files at 10 inches (Print Your Cause). Neither states a maximum canvas.

  • Custom Ink (all decoration methods) (platform): typical print size with raster pixel minimums at 200 and 300 DPI; vector is unaffected. Left chest or pocket 3.5 × 3.5 in, 700 × 700 px at 200 DPI, 1,050 × 1,050 px at 300. Full front medium 8 × 10 in, 1,600 × 2,000 and 2,400 × 3,000 px. Full front large 12 × 14 in, 2,400 × 2,800 and 3,600 × 4,200 px. Full back 12 × 16 in, 2,400 × 3,200 and 3,600 × 4,800 px. Hat front 2.5 × 2.5 in, 500 × 500 and 750 × 750 px. Sleeve 3 × 3 in, 600 × 600 and 900 × 900 px — Custom Ink: image resolution guide
  • Print Your Cause (platform): “a minimum resolution of 300 dpi (pixels per inch) scaled at 10 inches”; many garments print at or near 10 inch width, so a file saved at that size keeps its resolution across products — Print Your Cause: Screen printing, everything you need to know

Resolution at print size

Raster art: Custom Ink calls 300 DPI at print size the gold standard and accepts 200 (Custom Ink); Oregon Screen Impressions asks for 300ppi or larger (Oregon); Print Your Cause asks for 300 dpi as a minimum (Print Your Cause). Separation workflows state their own range: UltraSeps wants 200 to 300 dpi for the working file (UltraSeps).

File format

Custom Ink prefers vector (Custom Ink), Print Your Cause asks for a vector file (Print Your Cause) and Oregon lists vector formats first (Oregon). The separation software works on other files: the Simulated Process side of Separation Studio NXT takes PNG, TIFF or JPEG (Freehand: PMS colours in NXT).

Colour mode and profile

Which mode the file needs depends on the separation software: UltraSeps says work in RGB 8-bit (UltraSeps), Separation Studio NXT separates in RGB, not CMYK (Freehand: why NXT has no CMYK), and AccuRIP Emerald offers Separations only for CMYK, Multichannel or Duotone files (Freehand: Separations not available). Ask the shop before converting.

  • Freehand Separation Studio NXT (RIP): “engineered to separate and print using RGB colors, not CMYK”, because RGB gives a wider gamut — Freehand: why NXT has no CMYK
  • Freehand AccuRIP Emerald (RIP): in Photoshop the Separations option appears only in CMYK, Multichannel or Duotone mode; an RGB file shows no Separations option — Freehand: Separations not available
  • UltraSeps (RIP): “ALWAYS work in RGB mode”; for a CMYK separation, prepare the art in RGB and let UltraSeps convert — UltraSeps: user guide v3 (PDF)
  • UltraSeps (RIP): the “UltraSeps Custom Color.csf” file must be loaded; without it the channels do not render correctly because dot gain is not compensated — UltraSeps: user guide v3 (PDF)
  • UltraSeps (RIP): before outputting from Photoshop CS1 to CS4, delete the RGB channels or composite cluster above the separation channels; from Illustrator or CorelDraw the RGB channels must stay — UltraSeps: print PSD separation, CS1-CS4 (PDF)
  • RushOrderTees (platform; colour-selection help for all products): “Create your images using CMYK if possible; otherwise, they will need to be converted.” A customer-facing request, the opposite of the RGB-first advice from separation vendors, at a different stage of the workflow — RushOrderTees: colour selection

Transparency and alpha

Where an underbase is used the background must be transparent, with no white fill and no white around the art (UltraSeps); Print Your Cause adds no transparencies, opacities or drop shadows, because everything prints on a solid white underbase (Print Your Cause).

White handling

Mesh counts named for the white base run 160 to 230 (Freehand: printing a white base); the UltraSeps sheet gives 156 to 230 for the underbase and 200 to 230 for highlight white (UltraSeps film output). The underbase is flashed, so it counts as a colour and a press position.

  • Anatol (maker): the underbase is flash cured before colours print on it; a two-colour job with an underbase needs at least four print heads — Anatol: the tricky business of underbase
  • Anatol (maker): 125-150 mesh is a start for spot-colour underbases, 200+ for fine detail or halftones; use a separate white for underbase and top colour, because using the underbase as highlight “uses too much ink” — Anatol: the tricky business of underbase
  • International Coatings (ink maker): mesh 110 and 155 for a large ink deposit, such as athletic numbers and white on black fabric; 160, 180, 200 for an underbase white with a softer feel — International Coatings: choosing mesh
  • Wilflex Epic Bolt LC White (ink maker; low-cure product): pair with K2100 Epic Armor LC Gray as an underlay for dye-migration resistance on 100% polyester performance fabrics — Avient: Wilflex product selection guide (PDF)
  • Freehand Separation Studio NXT (RIP): the “Magic White” screen builds secondary and tertiary colours in Sim Process RGB images; KnockOut White removes data from colour screens so the base screen serves base and highlight — Freehand: KnockOut White
  • Freehand AccuRIP and Separation Studio (RIP): standard white base at 160-230 mesh; 160-180 for more ink, 200-230 for more detail and a softer hand — Freehand: printing a white base
  • UltraSeps (RIP): simulated process, mesh 280-305 for top colours, 156-230 for the underbase white, 200-230 for highlight white — UltraSeps: film output settings (PDF)
  • Promo Decorators (print shop): an underbase adds a screen and “slows production slightly (about 20%)”; a vendor estimate, not a measured figure — Promo Decorators: underbase screen printing
  • Custom Ink (platform): on 50/50 blends or polyester-heavy hoodies a grey underbase may be needed to prevent dye migration on darker or pigment-dyed styles — Custom Ink: hoodie printing methods

DTG prints the same white base on dark garments from the file, without a screen: see DTG: White handling.

Minimum line and text size

Lines of 1 pt, negative gaps of 2 pt and text of 6 to 8 pt are the floors: 1 pt and 6 pt at Custom Ink (Custom Ink), 1 pt and 8 pt at Oregon (Oregon), 1 pt for garments, 2 pt for hats and textured items, and 2 pt for negative space at Print Your Cause (Print Your Cause).

  • Custom Ink (platform): minimum stroke weight 1pt and minimum text size 6pt at print size — Custom Ink: screen printing custom T-shirts
  • Oregon Screen Impressions (platform): outline live fonts; fonts no smaller than 8pt, lines no thinner than 1 pt; inverse art and negative-space text need larger sizes — Oregon Screen Impressions: art guidelines
  • Print Your Cause (platform): lines at least 1 point for garments, 2 points for hats and textured items; negative spaces at least 2 points, or the lines “bleed together”; text converted to outlines in a vector file — Print Your Cause: Screen printing, everything you need to know
  • Teespring / Spring (platform; Wayback capture of 2022-05-19, live page blocked, not current policy): supply the typeface file for specific fonts; outline text in AI and EPS files, rasterize it in PSD and TIFF files — Teespring: Design Support, Wayback capture 2022-05-19
  • Freehand AccuRIP and Separation Studio (RIP): registration marks, four of them, one per corner, on the Registration swatch so they appear on all separations; 0.75 pt is a typical size — Freehand: registration marks
  • Ulano ExpoCheck, fine mesh (maker; exposure test positive, not a minimum-line spec): for mesh above 260 t/in with threads of 40 microns or less, line patterns of 50-250 microns plus 300 microns and fonts of 3-12 pt — Ulano: ExpoCheck (PDF)
  • Ulano ExpoCheck, medium mesh (maker; evaluation targets only): for 110-260 t/in, lines of 100-350 microns and fonts of 4-12 pt — Ulano: ExpoCheck (PDF)
  • Ulano ExpoCheck, coarse mesh (maker; evaluation targets only): for 110 t/in or less, lines of 200-500 microns and fonts of 10-14 pt — Ulano: ExpoCheck (PDF)

Bleed and safe zone

No source read states a bleed figure. UltraSeps asks for a working canvas slightly larger than the finished separation (UltraSeps), and two separation guides cover register marks and canvas resizing.

Ink limits and gradients

Custom Ink lists 1 to 6 spot colours (Custom Ink) and Underground Printing suggests 1 to 10 (Underground Printing). Gradients are out where a solid white underbase prints (Print Your Cause).

Halftone LPI, angle and mesh

The pairs the sources give: 46 LPI on 230 mesh at 22.5 degrees (Freehand: Don’t Fear Halftones), 55 LPI on 280-305 mesh at 26 degrees for simulated process (UltraSeps film output), and 45-50 LPI on 230 mesh for manual presses (UltraSeps film output). RIPs output film positives at a chosen LPI; the sources here use 45-60 LPI for simulated process and CMYK, and 300 or 50 LPI for spot work (UltraSeps film output). When the mesh count is unknown, ask the shop for its LPI and angle.

  • Freehand AccuRIP Emerald (RIP): the default screen is 30 LPI, the default angle 22.5 degrees, the default shape Round; “The common industry factor is 5 (e.g., 230 mesh ÷ 5 = 46 LPI max)” — Freehand: AccuRIP halftone settings
  • Freehand AccuRIP Emerald (RIP): an “industry standard 46 line screen halftone at an angle of 22.5 degrees”; the mesh count should be 5x the line screen, equal or next higher, “never a lower number” — Freehand: Don’t Fear Halftones
  • UltraSeps (RIP): simulated process, elliptical dot, 26 degrees at 55 LPI, mesh 280-305 for top colours, 156-230 for the underbase white, 200-230 for highlight white. CMYK: 22.5 degrees at 55 or 60 LPI (26 can also be used), mesh 305-330 top colours, 200-230 underbase white, 230 highlight white; print order white base, yellow, magenta, cyan, highlight, black — UltraSeps: film output settings (PDF)
  • UltraSeps (RIP): basic spot colour separations, elliptical dot, 26 degrees at 300 LPI with no tints and at 50 LPI with tints and gradients; mesh 156-200 for designs without a white base, 200-305 for top colours over a white base, 156-200 for the underbase white — UltraSeps: film output settings (PDF)
  • UltraSeps (RIP): manual printing may use lower LPI and mesh for simulated process, such as 230 mesh for top colours with films at 45-50 LPI at 26 degrees — UltraSeps: film output settings (PDF)
  • UltraSeps (RIP): “You’d never hold a 1% or 2% dot when exposing screens”, especially a white underbase on a lower mesh — UltraSeps: deleting fringe pixels from the white underbase
  • CADlink FilmMaker (RIP): highlights run 0-10% (smaller dots), midtones 10-90%, shadows 90-100% (larger dots) — CADlink: separations and halftones
  • Chromaline (maker): tensioning stretches mesh by 4-8%; a 195 mesh at 34 N/cm opens to about 183 threads per inch. Rule of thumb: LPI times 4.5 gives the lowest suitable mesh, 45 LPI x 4.5 = 202.5, so a 195/200 screen — Chromaline: harmonizing mesh count to line count
  • Chromaline (maker): the smallest printable dot is (2x thread diameter) + (2x mesh opening distance), so a finer mesh can hold a higher LPI with a good tonal range — Chromaline: harmonizing mesh count to line count
  • Ulano ExpoCheck (maker; exposure-test halftones, not recommended print frequencies): 85, 55 and 35 lines per inch at dot percentages of 10, 25, 50, 75, 85 and 90 — Ulano: ExpoCheck (PDF)
  • Murakami Screen USA (maker): “Higher mesh counts can be used with similar results to lower mesh counts. 45 and 55 line halftones can be imaged on 150LX and 180LX.” — Murakami: S-Mesh and LX-Mesh
  • Murakami Screen USA (maker): tonal values run from 0% to 100% (solid black on film); 1% to 99% become halftones; its Filmgate linearization uses a tonal ramp assigned a halftone value, 55 lpi for example — Murakami: linearization of halftones
  • SAATI Hi-Dro (maker; water-based ink mesh, TDS Rev 2 Oct 2024): mesh count in threads per inch / thread diameter in microns / maximum recommended tension in N/cm: 110 / 64 / 27-30; 122 / 55 / 24-26; 140 / 48 / 25-28; 157 / 48 / 25-28; 198 / 40 / 20-24; 230 / 40 / 20-24; 305 / 31 / 21-24 — SAATI: Hi-Dro mesh TDS (PDF)
  • International Coatings (ink maker): mesh 230, 280, 305 for low ink deposit, good for halftone, simulated process or CMYK; 355 for very low deposit, “generally used by very experienced printers only”, often for 65 line or higher halftones — International Coatings: choosing mesh

Pantone and spot colours

Pantone matching is a named request, and at the two shops that state it, a paid extra (Custom Ink, RushOrderTees).

  • Custom Ink (platform): enter Pantone colours via “Edit Colors” or the Upload panel’s “Need a Pantone Color Match?” prompt; each Pantone match is a paid extra — Custom Ink: match your ink colours
  • Teespring / Spring (platform; Wayback capture of 2022-05-19, live page blocked, not current policy): name any required PMS colours, or the closest PMS colours are chosen during vectorization — Teespring: Design Support, Wayback capture 2022-05-19
  • RushOrderTees (platform): Pantone Color Matching is an additional paid service — RushOrderTees: colour selection
  • Freehand AccuRIP Emerald (RIP): swatches from colour libraries, or process colours converted to spot, give a 100% solid swatch instead of a mix of process values — Freehand: spot colours in AccuRIP Emerald
  • Freehand Separation Studio NXT (RIP): symbols such as ! $ @ / in swatch names can cause errors opening the PDF; keep spot colour names to letters and numbers — Freehand: naming colour swatches

Trapping and choke

Choke runs from 0.05 pt, the NXT default for a vector PDF base (Freehand: base choke), to 2 pt (Freehand: base generation); Anatol says make the underbase a point or two skinnier (Anatol); UltraSeps chokes by 1, 2 or 3 pixels (UltraSeps). For trapping between colours, Trimingham sizes the trap from a test print (Screen Printing Magazine).

  • Freehand Separation Studio NXT (RIP): for a vector PDF base the Choke value applies to each separation; default 0.05 pts. Base Jump example: an exaggerated 1pt choke on all separations, then the base moved to the end of the line — Freehand: base choke in NXT
  • Freehand Separation Studio NXT (RIP): “CHOKE: Value up to 2 pt to improve on-press registration” — Freehand: base generation in NXT
  • CADlink Digital Factory (RIP): a choke of 2 pulls the underbase 2 pixels closer to the job bounds, preventing it “peeking out” — CADlink: Digital Factory Layer tab
  • UltraSeps (RIP): if white creeps beyond the top colours, choke the underbase by 1, 2 or 3 pixels; on a 100 dpi test file the effect is greatly exaggerated — UltraSeps: user guide v3 (PDF)
  • UltraSeps (RIP): a curve on the white underbase channel removes pixels in the 1%-6% range to clear fringe — UltraSeps: deleting fringe pixels from the white underbase
  • UltraSeps (RIP): if a gap could be an issue on press, a small trap is needed on some or all colours except black; the “Trap Spot Colors RUN” action helps; avoid trapping black, which adds line weight — UltraSeps: user guide v3 (PDF)
  • Scott Fresener (RIP, in Screen Printing Magazine): a 10 pixel white stroke at 600 dpi (5 pixels at 300 dpi) pulls the edge in by 5 pixels, 0.0083 in or about 0.6 pt; the article says “about 1 point” — Screen Printing Magazine: colour separations tips
  • Thomas Trimingham (in Screen Printing Magazine): define a minimum trap as double the largest gap in a test file; a 1/64-inch gap calls for a 1/32-inch trap. The article prints the point values as 2.25 and 4.5, twice the true values — Screen Printing Magazine: how to trap artwork
  • Anatol (maker): make the underbase “a point or two skinnier than your top colors”, called choke, to keep it inside the top layers of ink — Anatol: the tricky business of underbase

Where the sources disagree

Colour mode: RGB first, or CMYK

UltraSeps says “ALWAYS work in RGB mode” and let UltraSeps do any CMYK conversion (UltraSeps); Separation Studio NXT separates in RGB, not CMYK (Freehand). AccuRIP Emerald offers Separations only for CMYK, Multichannel or Duotone files (Freehand). RushOrderTees, on a colour-selection page for all products, asks customers to create images in CMYK if possible (RushOrderTees).

On the floor: the RushOrderTees line is a customer-facing request, made at a different stage from the separator’s working file, so it is not a direct clash with UltraSeps. The real split is between RGB-first separation software and AccuRIP’s host separations. Ask which one the shop runs before converting.

Mesh for a given LPI: 5x, 4.5x or a thin-thread mesh

AccuRIP says the mesh “should be 5x” the line screen, equal or next higher, never lower (Freehand). Chromaline offers 4.5x as a rule of thumb (Chromaline). Murakami says 45 and 55 line halftones can be imaged on 150LX and 180LX thin-thread mesh (Murakami), about 3.3x for 150LX at 45 and 180LX at 55.

On the floor: a shop on thin-thread mesh can hold the same LPI on fewer threads per inch than the 5x rule gives. Taking 5x is the cautious side of the AccuRIP wording; the mesh is the shop’s choice, not the file’s.

Underbase edge: fixed choke or a curve

Separation Studio NXT sets a 0.05 pt choke by default for a vector PDF base (Freehand). UltraSeps, for tonal raster fades, removes 1%-6% pixels from the white underbase channel with a curve (UltraSeps: deleting fringe pixels), and its user guide says choking “is not required, especially with photograhic and busy images” (UltraSeps user guide).

On the floor: these are different art types, so this is a contrast more than a conflict. Hard vector edges get a choke; soft fades get a curve on the underbase channel.

Halftone angle: 22.5, or 26 with a 56 degree fallback

AccuRIP’s default angle is 22.5 degrees (Freehand). The UltraSeps sheet gives 22.5 degrees for CMYK, with 26 also usable, and 26 degrees for simulated process and spot; for mesh interference on press it suggests the white base at 50 LPI and 56 degrees (UltraSeps film output, UltraSeps user guide).

On the floor: 22.5 and 26 are both in use, and the angle is set at film output, not in the customer’s file. Ask the shop’s separator for its values.

What fails on the floor

The cases below are descriptions from the cited pages. One, the halftone dots along vector edges, is illustrated with screenshots in the magazine article (Screen Printing Magazine); none comes with the file’s properties.

Halftones print where solid was expected

Symptom: halftone dots on film where a solid fill was wanted. Cause in the file: elements not set up as 100% spot colours, or Illustrator’s print dialog left in Composite instead of host-based Separations. “make sure that all elements in the file you want to print solid are set up using 100% spot colors” (Freehand: halftones printing instead of solids).

White box behind the graphic on dark garments

Symptom: a solid white box or blob behind the art. Cause in the file: raster art flattened onto white or surrounded by white is read as white ink and generated in the underbase and highlight channels (UltraSeps). Print Your Cause adds that opacities and drop shadows print as opaque (Print Your Cause).

White fringe or halo around soft fades

Symptom: white showing beyond a faded or glowing edge. Cause in the file: 1%-6% tonal pixels at the edge of a glow or fade in the white underbase channel. “the easiest way to make the adjustment is through the use of a simple Curve of the white underbase channel” (UltraSeps: deleting fringe pixels).

Halftone dots along vector edges

Symptom: small halftone dots along the edge of what was a clean graphic. Cause in the file: anti-aliasing left on when a vector file is opened in Photoshop or exported to PNG, which adds soft or semi-transparent edge pixels (Screen Printing Magazine, Freehand).

Screen printing moire

Symptom: an interference pattern on the print. Cause in the file: a halftone line count mismatched to the tensioned mesh count; mesh elongates 4-8% under tension, so a 195 mesh at 34 N/cm opens to about 183 threads per inch (Chromaline).

Lost highlight dots

Symptom: 5% dots missing or unfaithful in the print. Cause in the file: dots smaller than (2x thread diameter) + (2x mesh opening distance) (Chromaline). SAATI’s Hi-Dro figure shows that on a standard mesh “threads block the openings” at 5% halftone dots (SAATI).

Gap between outline and fill

Symptom: “a glaring white space between your image’s fill and its outline”. Cause in the file: no trap overlap; the article’s remedy is a trap sized from measured distortion, double the largest gap in a test print (Screen Printing Magazine: how to trap artwork).

Fine lines break up, narrow gaps close

Symptom: gaps in thin lines, and lines bleeding together. Cause in the file: strokes under 1 point (2 points on hats and textured items) “will not adhere to the garment”; negative spaces under 2 points let lines “bleed together” (Print Your Cause).

PDF fails to open in separation software

Symptom: errors opening the PDF in Separation Studio NXT. Cause in the file: spot colour swatch names containing ! $ @ or / (Freehand: naming colour swatches).

What shops ask on the forums

Six file questions came up in at least two threads since 2024. The quotes are the askers’ opening posts; replies are not used. The second question is the weakest: its two askers report different symptoms and one of them suspects exposure, which is not a file matter. One thread under the fourth question never says “screen printing” and is kept because it uses separation and underbase vocabulary. Questions about whether a garment colour needs an underbase were asked in several threads but concern press and ink, not the file, and are left out.

“How do I set a halftone LPI, and what mesh goes with it, without Photoshop?”

“is there any programs like photoshop where I can simply plug in a specific LPI or something similar” — Forum: Free or one time payment programs for halftones, October 2026. Also asked in Forum: Procreate brushes for creating CMYK illustrations with halftones at the correct angles and frequency?, September 2026: “I don’t know what the 30 means- 30 whats per what?”, where the asker’s frequency is for 90T mesh. And in Forum: questions from a newbie, October 2026: “I read about lpi but im not sure how to tell what it is on gimp”.

What our sources say: LPI is halftone cells per inch, and at 300 DPI a 60 LPI cell is 5 × 5 pixels (CADlink). The pairings are 46 LPI at 22.5 degrees on 230 mesh with mesh at 5x the LPI (Freehand), 4.5x as a rule of thumb (Chromaline), and 55 LPI at 26 degrees on 280-305 mesh for simulated process (UltraSeps). None says how to set the frequency in GIMP, Procreate or Illustrator (the LPI rows are all set in a RIP), and none converts a metric mesh count such as 90T to threads per inch.

“Halftones fail on the screen (moire, or small dots will not clear) at an LPI and mesh that look right: what do I change?”

“we see some moaré effect, and we don’t kow how to fix it.” — Forum: Problem with halftone prints…., March 2026. The asker gives 55 LPI films on 272 mesh and suspects exposure time. Also asked in Forum: Halftones Not Washing Out of Screen, January 2025: “Part of the design has some very small halftone dots that aren’t washing out.” That asker gives 40 or 50 LPI on 196 mesh and also states emulsion, exposure unit and time.

What our sources say: a halftone line count mismatched to the tensioned mesh gives moire, and a 195 mesh at 34 N/cm opens to about 183 threads per inch (Chromaline). Dots below (2x thread diameter) + (2x mesh opening) are lost, and at 5% dots threads block the openings (Chromaline, SAATI). For mesh interference on press, UltraSeps suggests the white base at 50 LPI and 56 degrees (UltraSeps). None covers dot shape, whether a pair still holds after tensioning at the asker’s tension, or exposure source and emulsion.

“A customer sends flat, low-resolution or AI art: how do I get separable art out of it?”

“What programs are you using to upscale the image, remove the background, vector and color seperate?” — Forum: How are you handling CANVA designs from customers?, May 2025. Also asked in Forum: Separating a flat image! HELP!, June 2024: “is there a way to separate colors here? or am I boned?” And in Forum: Customer provided AI art is driving me crazy, February 2026: “we are sent these low resolution, overly detailed, full color ai created images with spelling errors and broken lines.” The artist in Forum: Getting orig artwork printed, July 2024, asks: “What’s the best way to get these into a format that a screen printer can use for t-shirts?” and says a 300 dpi file was printed pixellated.

What our sources say: the target is raster at 300 DPI at print size (Custom Ink, Oregon Screen Impressions, Print Your Cause), or 600 dpi for small text (Screen Printing Magazine). Anti-aliasing adds soft edge pixels that separate as halftone dots (Freehand). None gives a method for getting separable art out of a flat, low-resolution or AI raster, or says what to do with a flat PSD.

“What software does separating a file need, does NXT run without Adobe, and can free tools make the channels?”

“Do I need accurip for color seperation?” — Forum: Screenprinting Halftones, August 2024. Also asked in Forum: opensource color separation tools, Scribus, Photopea?, August 2025: “Please tell me how to create CMYK separations without Adobe or paid programs”. And in Forum: Is Sep Studio NXT user friendly?, November 2025: “I was wondering if I need Adobe software to run it or if it’s a standalone software”. Two more threads ask what people use for separations: Forum: Trouble learning the graphics side of printing, February 2026, and Forum: Open Source Color Separation Software with Underbase capability?, October 2024, which does not name screen printing but asks for an underbase layer.

What our sources say: each tool wants a set colour mode. UltraSeps says work in RGB (UltraSeps), Separation Studio NXT separates in RGB (Freehand) and saves a PSD (Freehand), and AccuRIP Emerald offers Separations only for CMYK, Multichannel or Duotone files (Freehand). None says whether NXT runs without Adobe or how free tools make the channels. The “free or cheap” half of these asks is pricing, not file-side, and is not answered.

“What should the underbase cover, and how is the base layer set up?”

“How should I set up my base layer in Photoshop?” — Forum: Halftone Base Under Solid Colors?, August 2026. The asker wants a halftone base to avoid a thick print-flash-print white, and asks for an LPI on 200 mesh. Also asked in Forum: Multi color screen printing logo, May 2026: “I’m thinking I would have to do an undertone behind the green print or would you undertone behind the entire logo including the black?”

What our sources say: Anatol says use a separate white for the underbase and the top colour (Anatol); NXT KnockOut White removes data from colour screens so the base screen serves base and highlight (Freehand); UltraSeps gives mesh 156-230 for the underbase and 200-230 for highlight white (UltraSeps), and a white base at 50 LPI and 56 degrees against mesh interference (UltraSeps). None gives a rule for thinning the base to cut the feel, an LPI for a base on 200 mesh in a print-flash-print job, or handles a shirt colour that is part of the art.

“How much should the underbase be choked, and how much do adjoining colours need to trap?”

“So I have chopped the under base at 0.5, 0.4, 03, 1, 2 and even -0.05 but still no luck.” — Forum: MY underbase is overlaping the top colour on transparency film …, July 2024. Also asked in Forum: Underbase white and color 2 pixel choke problem ?, October 2025: “do you use different choke settings for the green color screen between the black and white shirts?” And in Forum: Wet on wet art, August 2025: “how many pts do you trap/choke?”

What our sources say: NXT chokes from 0.05 pt by default up to 2 pt (Freehand, Freehand); CADlink uses 2 pixels (CADlink); UltraSeps 1, 2 or 3 pixels (UltraSeps); Anatol a point or two skinnier (Anatol); and Trimingham sizes a trap at double the largest gap in a test print (Screen Printing Magazine). The first asker’s positive values up to 2 sit inside that range; the -0.05 is a spread, not a choke. None gives a wet-on-wet rule, or says whether the choke changes between a white and a black shirt.

Preflight before you upload

Sources, checked on 2026-10-21

Forum threads

Could not check

  • teespring.com: HTTP 403 to the fetcher; the bullets link the Wayback capture of 2022-05-19 and are labelled as that capture, not current policy.
  • sefar.com (two screen-printing product pages): HTTP 429; nothing in the guide depends on them.
  • www.screenprinting.com: three articles on white base chokes and separation software returned HTTP 429 to the collector (HTTP 200 to the checker); no row cites them, so nothing in the guide depends on them.
  • www.saati.com 2025 printing catalogue PDF: HTTP 404; the Hi-Dro 2024 TDS was read instead.
  • www.customink.com legacy help-centre pages on file types and raster versus vector: HTTP 404; the 2026 Custom Ink guides and the Pantone help page were read instead.
  • Maximum print area or canvas for separation RIPs: no usable figure in the rows that passed the check.

Verdicts on claims in this guide

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