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Guided workflow variation

A white underbase for dark shirts,choked so it stays hidden.

Bright inks on a black tee need white beneath them. Underbase builds that plate from the inks you tick, pulls its edges in by the amount you set, and shows it against the garment color before a single positive is printed.

Tick the inks that need white beneath them, set the choke, preview the plate on the garment, and the underbase prints as its own film page.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Full Underbase overview
One-time purchase No telemetry Local-first

windows · runs on your pc · no account · nothing uploads · 15-day free trial

If this sounds like your week

Building the base by hand is the slowest part of a dark-garment job.

The usual recipe is tedious: combine the selections for every bright color into one mask, contract that mask by a few pixels, fill it with white, decide which deep tones should skip it, and save the result as a separate channel. Then repeat for the next order, because each design has different shapes. Navy lettering, for example, often looks richer printed straight onto a black blank than sitting on a white pad.

Where tooling usually breaks

Too wide and it halos. Too tight and it gaps.

A base that matches the top colors exactly will peek out wherever registration wanders by a hair, leaving a bright fringe around letters. Pull it back too far and the colored ink loses brightness along every edge. Get the coverage wrong and you also spend extra white, a longer flash, and a stiffer hand than the job needed, and the customer notices.

Where Underbase lands

Tick, choke, preview, and print.

In Underbase each ink row carries a UB checkbox; deep tones start unticked and a notice explains it. The Choke field moves in 0.05 mm steps and its helper shows the same amount in source pixels. Show underbase plate draws the white plate alone, and Show plate on garment lays any plate over Black, Navy, Heather, Red, Forest, or Sand swatches. Tint and halftone the base when a softer feel matters.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Learn more about Underbase

windows · runs on your pc · no account · nothing uploads · 15-day free trial

What you get

Feature highlights

Spot or index separation from the files customers send

PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF, and Illustrator (.ai) files, with close shades grouped, the background left unprinted, and shaded art dithered between a fitted set of inks.

A choked white underbase

built from the inks you tick, pulled in from 0 to 3 mm in 0.05 mm steps, with dark inks printing straight on the shirt and a preview on seven garment colors.

Trapping in one click

spread or choke any ink from -3 to +3 mm, or apply the default trap to every ink so lighter colors tuck under the darkest.

Halftones tuned to your press

screen any plate at your ruling, angle, and tint, take a ruling suggested from the mesh, thin halftones for measured dot gain, and check the output dots before film.

A plate budget you can see

Underbase counts the underbase and every printing ink against the screens your press holds, holds generation until the job fits, and merges inks to fit in one click.

True-size film and a production ticket

a film PDF with identical registration marks and plate labels, one plate per sheet or ganged, 1-bit TIFFs at up to 1440 dpi, and a ticket as PDF and JSON.

Especially when

  • Turn a customer PNG, JPEG, SVG, PDF, or Illustrator file into one plate per ink without selecting colors by hand in a design program
  • Build a white underbase for dark shirts that is choked so it never shows at the edges, and keep dark inks off it
  • Know the plate count before burning a screen, and merge inks to fit the screens the press holds
  • Print film positives at true size with registration marks and plate labels, plus a production ticket, without sending the job to an outside separator

Who benefits

Real-world scenarios

A three-color surf logo on black tees

The design is navy waves, a coral sun, and cream lettering, printed on black cotton. Coral and cream need white beneath them to read; the navy should print straight on the shirt.

Underbase finds the three inks, ticks UB on coral and cream, and leaves navy unticked with a notice saying it will print directly on the garment. The base is choked 0.25 mm by default, and the plate budget shows 4 of 6 plates: the base plus three inks.

A manual press with loose registration

An older four-color manual press drifts slightly between prints, and white has been showing at the edges of bright letters on dark hoodies.

The operator raises Choke from 0.25 to 0.4 mm. The helper shows the new amount in source pixels, and Show underbase plate confirms the base now sits well inside every letter before the film is printed.

A softer hand on heather shirts

A customer wants a vintage look on heather tees, with the shirt showing through slightly and less ink weight than a solid white base gives.

The operator turns on Halftone the underbase, lowers the tint, and uses Suggest ruling from mesh for the base screen. The ruling and mesh print on the film label and the production ticket, so the screen room burns the right screen.

Deep dive

How Underbase builds, chokes, and outputs the underbase plate

What goes into the base. Turn on Print a white underbase first and Underbase builds the base from every printing ink with UB ticked. The plate is named Underbase White by default; rename it under Underbase plate name if your shop uses another name. The base is always counted in the plate budget and printed first in the order.

Dark inks print straight on the shirt. Deep tones such as navy or black usually look better without white beneath them, so Underbase leaves dark inks unticked and says so in a notice: Navy will print directly on the garment. Tick UB on that row if this job needs it under the base.

Choke in millimeters and pixels. The Choke field runs from 0 to 3 mm in 0.05 mm steps, with 0.25 mm as the default. Its helper shows the same amount in pixels at the source resolution and suggests a typical range of 0.2 to 0.5 mm, with more on loose mesh or manual presses. The choke is computed with a distance transform on the mask, so the edge pulls in evenly around curves and corners.

Check it before film. Show underbase plate switches the preview to the base alone, labeled with its name, choke, and screening. In the Plate tab, Show plate on garment draws the current plate over the shirt color: pick Black, White, Navy, Heather, Red, Forest, or Sand, or type a hex value for the garment. The Composite tab shows the whole print on the same color.

Solid, tinted, or halftoned. The base prints solid by default. Set a tint for a lighter base, or turn on Halftone the underbase and choose the screen ruling and angle. Suggest ruling from mesh sets the ruling from the base mesh at 22.5 degrees and turns the halftone on. Dot gain compensation applies to the halftoned base too.

Highlight white on top. A light top white is a separate ink from the base. Suggest print order (white last as highlight) puts colors from light to dark, black next to last, and the white ink on top, so the base and the highlight white each get their own screen.

Where it lands. Generate underbase pack writes the base as its own page in the film PDF, its own 1-bit TIFF in film-tiff, an unscreened channel in channels, and a row on the ticket with mesh, screening, and coverage. The ticket also records the choke so the next run of the job matches.

How it is built

Built for the press, not the design studio.

The press sets the limits

You enter the screens your press holds, the mesh, and the dot gain you measure. Underbase counts every plate against that budget and thins halftones to match before any film is written.

Film at true size

Every plate lands on the sheet at true size with identical registration marks, center ticks, and a label naming the job, plate, ink, screening, offset, and mesh.

Nothing uploads

Underbase runs entirely on your PC with no account, no telemetry, and no network connections. Customer artwork is only read. One-time purchase in the Microsoft Store.

Head-to-head

How Underbase compares

Feature Underbase Building it by hand Outside separation service
Base built from chosen inks Yes, tick UB on each ink Selections merged one by one Built by the service
Choke amount 0 to 3 mm in 0.05 mm steps, shown in pixels too Contract the selection and check by eye Set by the service
Dark inks left off the base Yes by default, changed with one tick Decided for each job Varies by service
Preview on the garment color Seven garment swatches or your own hex color Mock-up by hand Proof on request
Halftoned or tinted base Yes, with ruling, angle, tint, and a ruling suggested from the mesh Extra steps On request
Output Its own film page, 1-bit TIFF, and line on the ticket Exported as another file Delivered as files

FAQ

Straight answers—no glossary dump

How much should I choke a white underbase?

Underbase starts at 0.25 mm and suggests a typical range of 0.2 to 0.5 mm, with more on loose mesh or manual presses where registration moves more. Type a value or use the plus and minus buttons in 0.05 mm steps, up to 3 mm. The helper under the field shows the same amount in pixels at the source resolution, and Show underbase plate lets you check the result.

Which inks should sit on the white underbase?

Bright and light inks, such as reds, yellows, oranges, and light blues, usually need white beneath them to read on a dark shirt, while deep tones like navy and black often print well straight on the garment. Underbase ticks UB for the lighter inks and leaves dark inks unticked, with a notice. Change any row with one tick, and the base and plate count update.

Can the underbase be halftoned for a softer hand?

Yes. Turn on Halftone the underbase and set the screen ruling, from 10 to 120 lpi, and the screen angle, or use Suggest ruling from mesh to set the ruling from the base mesh count at 22.5 degrees. You can also set a tint for a lighter solid base. The Output dots toggle in the Plate tab shows the halftoned base at the output resolution.

Does my customer's artwork stay on my PC?

Yes. Underbase runs entirely on your PC. There is no account, no upload, and no telemetry, and the app makes no network connections. It reads the artwork you open, writes each job to a folder inside the output folder you choose, and keeps its own settings in local app data. Jobs save as .underbase files you can reopen for a repeat order.

How do I get Underbase, and is there a trial?

Underbase is a one-time purchase in the Microsoft Store, and the listing shows the current price in your currency. The Store runs a 15-day free trial, so you can separate a job you have already printed, or one of the six bundled samples, and compare the film with what you burned. The Store installs and updates the app. It runs on Windows 11 version 24H2 or later on x64 PCs.

Related pages

Flat-color tee art, split into one plate per ink. Film positives at true size, with the dots you set. From customer art to film, in one separation app.

Customer art in.
Press-ready film out.

Underbase separates flat and shaded art into spot inks, builds a choked white underbase, traps colors in one click, keeps the job inside your plate budget, and writes true-size film with registration marks and a production ticket. Everything runs on your PC, and the Microsoft Store runs a 15-day free trial.

Pay once. Own it forever.

One-time purchase on the Microsoft Store · No subscription · Instant install

Get it from Microsoft

Buy through the Microsoft Store—instant install, automatic updates, and a Microsoft receipt for easy expensing. No account needed on our site, and no subscription on Store purchases.

Open full product page

Illustrator is a trademark of its owner, registered in the U.S. and other countries. Underbase opens Illustrator (.ai) files as an input format and is not affiliated with or endorsed by the trademark owner.

Technical specifications

Technical specifications for procurement

Spec Implementation
Data Sovereignty Reads only the artwork you open or drop on the window and never writes to it; writes each job (film PDF, TIFF plates, channels, ticket, preview, and .underbase job file) to a folder inside the output folder you choose; settings stay in local app data on this PC
Telemetry Status None; no account, no upload, no telemetry, and no network code in the app
Core Runtime .NET 10 and WPF, self-contained, distributed through the Microsoft Store as an MSIX package; separation, halftoning, TIFF, and PDF output run in the app’s own engine, with PDF and Illustrator (.ai) pages rendered by a bundled PDFium engine
Network Requirements Fully functional offline; the app makes no network connections and nothing is uploaded
Deployment Compatibility Windows 11 version 24H2 or later (10.0.26100), x64; 8 GB RAM recommended for very large artwork, about 400 MB of disk; one-time purchase in the Microsoft Store with a 15-day free trial
Inputs PNG, TIFF, JPEG, BMP, GIF, WebP, SVG, PDF, and Illustrator (.ai) files; vectors rasterised at 300 dpi at true size; print size from the file’s resolution tag or a print width you set, in inches or millimeters
Separation Spot mode (one ink per flat color, close shades grouped, background left unprinted) or index mode (error-diffusion dither between a fitted ink set, dither strength 0 to 100); reduce to 1 to 16 inks; rename, merge, reorder, or switch off any ink
Underbase and traps White underbase from the inks you choose, choke 0 to 3 mm; spread or choke per ink from -3 to +3 mm; one-click trapping of every ink under the darkest; suggested print order with highlight white
Screening Solid or halftone per plate at 10 to 120 lpi, any angle, with tint; ruling suggested from mesh count; dot-gain compensation from 0 to 50 percent; output dots preview at the output resolution
Outputs True-size film PDF with registration marks, center ticks, and plate labels, one plate per sheet or ganged, mirror for emulsion down; 1-bit CCITT G4 film TIFF per plate at 600, 720, 1200, or 1440 dpi; unscreened 8-bit channel TIFFs; production ticket as PDF and JSON; preview PNG; .underbase job file
Film sizes Letter, Legal, Tabloid, Super B, ANSI C, A4, A3, A3+, A2, or a custom sheet up to 60 x 120 in; direct printing to any Windows printer