RGB mockups look punchy on screen; CMYK on paper often mutes colors and shifts neutrals. For machine-readable symbols, the priority is edge sharpness and contrast—not brand cyan. Barcodes and QR codes are usually safest as 100% black on a clean white or light field; “rich black” mixes (C+M+Y+K) can spread unevenly under dot gain and blur module edges.
Dot gain means printed dots grow compared to the digital file—especially on uncoated stock and consumer laser printers. If your proof looks crisp on coated glossy paper but the production run uses matte labels, re-verify module width and the minimum X-dimension your scanner vendor quotes.
Resolution and vector workflow
Export QR and linear barcodes as vector (PDF/EPS/SVG) when the RIP allows—raster upscaling creates soft edges. If you must use PNG, generate at the final print width at 300 DPI or higher for plate or digital label presses; lower resolutions may look fine to the eye but fail ISO verification.
Batch workflows should freeze one “golden” export per SKU revision: filename, dimensions, and checksum. When marketing requests a last-minute color tweak on the surrounding artwork, re-link the same barcode asset so the encoded payload cannot drift silently.
Margins, bleed, and imposition
Custom sheet jobs need enough margin so guillotines do not cut into quiet zones. Add bleed only to artwork that touches the trim—never clip the quiet zone to “save space.” Print an alignment sheet with crop marks and measure the first article before committing thousands of labels.
Verification before full runs
- Use a handheld verifier or supplier-grade scan if available; phone cameras are a sanity check, not a certificate.
- Test after rubbing with dry cloth and with a dab of oil—retail labels see worse abuse than office proofs.
- Archive PDF proofs with embedded fonts and placed barcode graphics for audit trails.