Artwork for Custom Mailers: A Practical Preparation Guide

Custom compostable mailers are printed at scale — potentially thousands of units in a single run. An artwork issue that is small on a screen becomes very visible across an entire production run. A logo that is slightly pixelated, a colour that does not match the brand reference, a design element clipped at the edge — these problems are much cheaper to identify at the artwork approval stage than to discover when the stock arrives.

Preparing artwork for custom mailers does not require a specialist print design background. It requires the right files in the right format, an understanding of a few key print concepts, and either the assets to supply them or access to design support to prepare them. Zero Pack offers free design support — and many brands start with nothing more than a PNG logo and a HEX colour code, which is enough to begin.

This guide covers the practical requirements: what files to prepare, how to handle colours, what safe zones and bleed are, how to write disposal instructions, and what to send your designer before they start. For the full production process from enquiry to delivery, see the How Custom Compostable Mailers Work guide.

The most important thing to understand about file format is the difference between vector and raster. A raster image — PNG, JPG, TIFF — is made up of pixels and becomes blurry when enlarged beyond its native resolution. A vector image is made from mathematical paths and scales to any size without quality loss. A vector logo will print sharply at 30 mm or 300 mm.

Print colour does not work the same way as screen colour. Screens display colour using RGB — red, green, blue light. Print uses CMYK — cyan, magenta, yellow, and black inks. The same colour reference can look different in each mode, and some vivid screen colours cannot be accurately reproduced in CMYK print.

Pantone (PMS) colour references are the industry standard for accuracy. Pantone colours are physical ink standards — a printer matching Pantone 485 knows exactly what formulation to use, regardless of screen calibration. If your brand has Pantone references, supplying them ensures the most consistent match. If you do not have Pantone references — many smaller brands do not — HEX codes are the next best option. Zero Pack can convert HEX to the closest Pantone equivalent as part of the artwork process.

If your design extends to the edges of the mailer — a full-bleed background, a pattern covering the entire surface, or a logo positioned close to the edge — you need to understand safe zones and bleed margins.

Bleed is extra artwork that extends beyond the final edge of the mailer. Because production cutting is not perfectly precise at the millimetre level, artwork that ends exactly at the intended edge may show a small white margin if the cut runs fractionally inside. Bleed — typically 3–5 mm of artwork beyond the intended edge — ensures any cutting variation is within the coloured area. Safe zone is the inverse: a margin inside the intended edge where critical content — your logo, any text — should not be placed. Anything too close to the edge may be clipped. A typical safe zone is 5–10 mm inside the finished edge. If you are working with a graphic designer, letting them know the files are for custom mailer production is sufficient — they will handle safe zones and bleed from there.

For compostable packaging, disposal instructions on the mailer are both a best practice and increasingly a regulatory requirement in some markets. The instruction must match the specific certification of your material. Designing disposal messaging into the layout from the start avoids retrofitting text that disrupts the design — which is the most common problem.

Example wording by material type:

If you work with an external graphic designer, the briefing they need for a custom mailer job differs from a web or social media brief. Sending them the following information before they begin prevents the most common revision rounds.