Bag Printing Artwork Checklist: Avoid Rejection & Delays

Most artwork rejections on custom bag orders are not creative problems — they are technical ones. A logo that looks perfect in a brochure can fail on a 340 GSM canvas tote because the file is 120 dpi, the type is not outlined, the Pantone reference is a paper shade that cannot exist in dye, or a 0.2 mm line disappears into the weave on the first pull. Every one of those failures is preventable before the file leaves your desk. This is the pre-flight checklist professional printers run against incoming artwork, item by item, with the thresholds that decide pass or reject.

What a printer needs before the first sample

A complete artwork package contains four things: the vector source file, a colour reference (Pantone or CMYK with swatches), the intended print dimensions, and placement instructions against the bag's seam lines. Missing any one of these costs a sampling round. The strongest package is the vector file plus a 300 dpi raster proof at the true print size — the vector for scaling and separation, the raster so the printer can see exactly what you approved. Placement matters too: specify distance from seams, handle drops and the top hem, because those are the dimensions that decide whether a print can be registered at all.

Vector vs raster: the format decision

Vector artwork — AI, EPS, PDF or SVG with live paths — is resolution-independent and is the only format that can be scaled, separated and trapped without quality loss. Raster files — PSD, TIFF, PNG or JPG — are acceptable only if they meet a hard threshold: 300 dpi at the actual print dimension. Below 150 dpi at print size, reject or re-build; the print will show jagged edges and bleeding halftones that no press setting can fix. One exception: full-colour photographic prints for DTF or sublimation are raster by nature, and there the ceiling is the source file itself — a 1,200 dpi film printer cannot invent detail that a 72 dpi web export never contained. The failure mode on woven fabric is specific: interpolated edges soften into a fuzzy outline at print size, and the halftone dots that carry grey tones break up across yarn crowns, leaving a speckled, muddy image. If the original vector artwork still exists, re-export from that source — tracing a low-resolution file adds artifacts of its own that only appear once the print is on cloth.

Minimum line weight and text size

Fabric is not paper. A 8 oz canvas surface has yarns and interstices that swallow fine strokes, and every decoration method has a floor below which detail simply disappears. For screen printing on canvas, hold lines to 0.3 mm or thicker; on 12 oz (400 GSM) fabric, go to 0.5 mm. Reverse-out (knockout) text is the classic casualty — thin counters close up under ink gain, so keep reversed lettering at 2 mm stroke minimum. Embroidery is the most restrictive: letter height below 8–10 mm loses legibility because stitch paths cannot reproduce tiny serifs. DTF and sublimation tolerate finer detail, but a practical floor of 0.3 mm keeps the design robust across production runs.

Pantone matching: TCX vs TPX and the coated-fabric reality

Pantone issues two relevant swatch systems. TCX (Textile Cotton eXtended) shades are dyed on cotton and represent what a fabric actually absorbs; TPX (Textile Paper eXtended) is the paper equivalent. For bag fabric, match to TCX, not TPX — a paper shade assumes a smooth, coated surface that absorbs no dye, while cotton canvas reflects colour differently because the yarn scatters light. The same Pantone number also behaves differently across substrates: a 6 oz natural canvas reads warmer and lighter than a bleached-white 10 oz canvas because the grey fabric shows through the ink film. Do not approve a colour from a screen or a paper fan deck. Ask for a lab dip or print swatch on the actual fabric, and accept a commercial tolerance of roughly ΔE 1.5–2 measured with a spectrophotometer under D65 lighting. Spot-colour builds differ between the coated reference and the substrate too: on coated stock the ink lies on a sealed surface, while on canvas the film spans the yarns, so pale shades read speckled and may need a second flood coat or a white underbase. If the logo will be dyed into the fabric rather than printed on it, the build is a dye recipe rather than an ink lay-down — expect a wider shade tolerance and approve the result on a lab dip.

Colour separation, trapping and registration tolerance

Every spot colour in a screen-printed design becomes its own screen, which is why 1–4 colour logos dominate the category. Separation is the job of deciding how those colours overlap, and it is done in the artwork, not on the press. Two rules govern it. First, adjacent spot colours must share a slight overlap — 0.15–0.3 mm of spread or choke — so that registration error does not open a white hairline between them. Second, anything claiming to be full-colour needs either a process (CMYK halftone) separation, which is visible on canvas at typical rulings, or a move to DTF/sublimation, which handle continuous tone natively. Black-and-white logos that will print on coloured fabric need a decision up front: print the black as solid ink, or reverse it out and let the fabric carry the colour.

Registration tolerance: the numbers on fabric

Registration is the physical alignment of one colour layer to the next, and on fabric it is measured in fractions of a millimetre that the weave constantly threatens. A realistic registration spec on flat tote panels is ±0.5 mm; on gussets and curved panels it loosens because the fabric is cut on the bias and shifts under the squeegee. Trapping is the insurance: by overlapping neighbouring colours slightly (spread the lighter colour, choke the darker one) you make the ±0.5 mm error invisible. Ask your supplier what registration tolerance their equipment holds on your fabric — if they answer "we just line it up by eye," that is a red flag; the answer should be a number.

Bleed and placement on curved panels

Print placement interacts with the bag's construction more than buyers expect. A print crossing a seam, gusset fold or hem will distort, crack at the fold line, or both — so artwork boundaries should sit at least 10–15 mm clear of seams and 20 mm from gusset fold lines. If the design must run edge to edge, add 3–5 mm bleed beyond the panel cut line so fabric tolerance of ±1 cm cannot leave an unprinted sliver. On curved panels, remember the pattern piece is two-dimensional: a logo spanning a curved side must be adjusted for the curvature or it will look stretched. The golden sample is where placement is locked — approve it with a tape measure, not a nod.

Common artwork rejection reasons

What to include when you send your artwork

Build the package once and reuse it: vector master file, outlined fonts, Pantone TCX references with acceptable tolerance, print size in millimetres, placement diagram against the bag panels, and a 300 dpi raster proof. A supplier that cannot work from that package will waste your sampling budget; one that asks the right questions about substrate and wash performance is worth the conversation. Wenzhou Conlene Bags Co., Ltd. runs a 4-stage in-house QC that begins with an artwork check — flags on resolution, trapping and placement are raised before any screen is burned, not after. Upload your logo through the customization and design support service and the development team will return a technical feedback sheet with any corrections needed, plus printed colour swatches on your chosen fabric. For a full rundown of what happens after the artwork is approved, from pre-production sampling through bulk QC, contact Conlene and the sampling schedule will be laid out within two working days.