Definition
File Requirements for DTF and UV DTF production at Long Island DTF Printing. Every transfer line prints from a 300 DPI raster file with a clean alpha channel. Preferred format is PNG with transparent background sized to the actual print dimension. PDF, AI, EPS, and SVG vectors also accepted. Common failure modes and the submission checklist below.
File prep is where most decorators lose hours. The fixes are not complicated, but they have to be done before submission, not after the transfers arrive. Every transfer line at Long Island DTF prints from a 300 DPI raster file with a clean alpha channel. Get those two facts right and most other issues disappear.
Submission checklist
- Final file is 300 DPI at the actual print size, not scaled up from low resolution.
- Background is transparent. No white box around the artwork.
- Color mode is RGB, sRGB profile embedded.
- All text is converted to outlines or rasterized.
- All effects, smart filters, and adjustment layers are flattened.
- No spot colors. No Pantone references unless previously discussed with production.
- Hairline strokes are 1.5 pt or thicker at final size.
- Smallest text is 6 pt or larger when going on a dark garment.
- File is named clearly: jobname_size_v01.png. No spaces.
Rules reference
| Spec | Value | Notes |
|---|---|---|
| Resolution | 300 DPI at final print size | Lower resolutions cause edge pixelation and banding on full-tone fills. |
| Preferred format | PNG with transparent background | Transparent alpha removes the need for manual knockout. |
| Accepted formats | PNG, PDF, AI, EPS, SVG | Vector files are rasterized at 300 DPI on intake. |
| Color profile | sRGB | CMYK files are converted at intake. Convert in-house if exact match matters. |
| Color mode | RGB 8-bit | 16-bit and 32-bit files are flattened to 8-bit before RIP. |
| Minimum stroke | 1.5 pt at final size | Hairline strokes under 0.75 pt drop out during the white underbase pass. |
| Minimum text height | 6 pt on dark, 4 pt on light | Below this point size, fine serif details lose legibility. |
| Alpha channel | Premultiplied or straight, both accepted | Anti-aliased edges over transparent backgrounds reproduce cleanly. |
| Bleed | None required | DTF and UV transfers cut to the artwork edge, no trim needed. |
| Layer flattening | Required before submission | Live text, smart objects, and effects must be rasterized. |
White knockout on dark garments
Standard DTF includes an automatic white underbase. The RIP generates the white channel from the alpha and the color data. No manual knockout is required for standard DTF. For Crystal White DTF on dark garments, the entire white underbase is replaced with a tuned bright-white formulation, also generated automatically by the RIP. The decorator does not need to supply a separate white plate.
Gold and silver foil is the one exception, and it is a file-prep exception rather than a colour-channel one. The metallic areas are printed as their own transfer, so what you submit decides what foils. If the whole design is metallic, send one file and you receive one transfer. If only part of it is metallic, send TWO files: one containing ONLY the metallic areas with the colour removed, and one containing the full-colour artwork with the metallic areas removed. How you size those two files depends on where the metal sits. When the metallic areas sit INSIDE the colour artwork, export both files on the SAME canvas, do not move, resize or re-crop either one, and the shared canvas registers them for you at the press. That is the recommended default because it removes the alignment work entirely. It is not a requirement: when the metal OUTLINES the colour or extends past it, the metallic file is wider than the CMYK file by design, so size each file to its own artwork. Each half is then quoted on its own square inches. What we cannot work from is a single merged file, which cannot be separated for you and is the most common reason a foil order is paused.
Alpha channel handling
Soft edges, drop shadows, and feathered halos reproduce cleanly because the RIP reads the alpha channel directly and applies a matching gradient to the white underbase. The shadow lifts off the garment with the same softness it has in the file. The common mistake is exporting from Photoshop with a hidden white background layer turned on, which produces a hard white halo around the entire design. Always preview the file against a transparency grid before submitting.
Vector files
AI, EPS, PDF, and SVG submissions are rasterized at 300 DPI at intake. The vector is preserved as the source of truth. If you anticipate resizing the same artwork across multiple jobs, submit vector. If the file already contains photographic content, submit the highest-resolution PNG or TIFF available. Mixed files with embedded raster inside vector are accepted, but the embedded raster must already be at print resolution at the intended placed size.