Preparing artwork

Production rarely stalls because something is hard to make. It stalls because a file arrived that cannot be used, somebody had to ask, and the answer took two days. Almost all of it is preventable in the twenty minutes before you send.

Vector or raster, and why it decides everything after

Vector artwork — Illustrator, EPS, PDF, SVG — is made of mathematical paths. It has no resolution and can be scaled to any size with no loss. Colours are discrete, named objects, which means they can be separated onto screens.

Raster artwork — Photoshop, PNG, JPEG, TIFF — is a grid of pixels. It has a fixed resolution and degrades when enlarged. Colours are per-pixel, which is what makes photographs possible and separations hard.

This single distinction determines what is possible downstream:

• Screen printing wants vector, because each colour must become a separate screen.
• Embroidery wants vector, because the digitiser is tracing paths into stitches.
• DTG, DTF and sublimation are happy with raster, because they reproduce continuous tone natively.

Sending a raster file for a screen-printed job is not fatal — it can be redrawn — but redrawing is someone’s afternoon, and the redraw is an interpretation of your design rather than your design.

Resolution, stated properly

The rule is 300 DPI at final printed size. The qualifier is the part people miss.

A file that is 300 DPI at 10cm wide is 150 DPI at 20cm wide. Enlarging does not add detail; it spreads the detail you have over more area. If a back print is going to be 30cm across, the file needs to be 300 DPI at 30cm, which is roughly 3,500 pixels wide.

Two things that look like resolution and are not:

• Upscaling. Software that enlarges an image invents pixels. AI upscalers invent them convincingly, which makes the result worse to review, not better — it will look sharp on screen and mushy in print.
• A large file size. A heavily compressed JPEG can be physically large and still carry visible artefacts, which become very visible once printed at size.

Colour

Three systems, used for different things, and conflating them is where colour surprises come from.

RGB is additive light — what your monitor does. It has the widest range of the three and it is not achievable in ink. Design in it if you like; do not specify in it.

CMYK is subtractive process ink. It is what DTG, DTF and sublimation work in. Its range is narrower than RGB, and the colours that fall outside — vivid oranges, deep blues, anything fluorescent — get mapped to the nearest achievable value automatically and without telling you.

Spot colours are pre-mixed inks specified by a standard such as Pantone. Screen printing uses these. A spot colour is a physical recipe rather than a mixture of process inks, which is why it is the only way to get a brand colour consistent across runs, suppliers and years.

If your brand has a defined colour, know its spot reference. If it does not, defining one is worth doing before the first production run rather than after the second one comes back looking different.

Fabric shifts colour. Ink is translucent and the garment underneath contributes. The same ink prints differently on white, on heather grey and on black, and on a dark garment it needs a white underbase to read at all. This is normal and expected — it is why a strike-off exists.

What to send

For anything screen-printed or embroidered:

• Vector source, with all text outlined and all effects expanded
• Colours specified as spot references
• Artwork at, or proportional to, final printed size
• Every placement as a separate file, named for its placement

For digital decoration:

• 300 DPI at final size, CMYK, PNG or TIFF
• Transparent background where the garment should show through — a white box around a logo prints as a white box
• Flattened, unless you specifically need layers preserved

For everything:

• A mockup showing placement and size on the garment
• The size the design should print at, in centimetres or inches — not “large”

The problems that actually happen

Text that was not outlined. The font substitutes silently and nobody notices until the sample.

A white background nobody saw. Extremely common with logos exported as JPEG, which has no transparency. On a white garment it is invisible on screen and invisible in print. On any other colour it is a rectangle.

Artwork scaled up in the wrong software. A vector logo pasted into Photoshop becomes raster at whatever resolution the document was, permanently.

Effects that do not exist in the process. Drop shadows, glows and transparency are continuous tone. In screen printing they must be simulated with halftones, which needs an extra screen. They either cost more or get removed, and it is better to decide which on purpose.

Small text and fine lines in embroidery. Thread has a physical width. Below roughly 5mm cap height, letterforms fill in and stop being legible. This is not a quality problem to be solved by trying harder; it is the medium.

Before you send

• Open every file on a machine that is not yours
• Zoom to 100% at final print size and look at the edges
• Check nothing is white-on-white
• Confirm the colours are specified, not just visible
• Say where it goes and how big

Twenty minutes of that removes most of the back-and-forth that otherwise happens after the clock has already started.