4 Pre-Press Preparations Before Sending Design Files to the Printer: Bleed/Resolution/Color Mode/Fonts — Clients Most Often Trip Up on Fonts Not Being Converted to Outlines

In August 2024, a client in cosmetics packaging came to us. The client's exact words:

"Our designer sent the AI file to the printer, but when the printer opened it, all the fonts turned into the default SimSun — it turns out the designer never converted the fonts to outlines. The entire batch of design files had to be redone, delaying the project by 5 days and costing 8,000 RMB."

This is a real pre-press preparation mistake. Before a packaging printer takes a digital printing order, 4 pre-press preparations must be sorted out.

Preparation 1: Bleed 3mm

What is bleed? The edge of the design file must extend 3mm beyond the actual print size, leaving margin for trimming.

Why 3mm? The printing industry standard bleed is 3mm (some printers require 5mm). Less than 3mm tends to leave white edges; more than 3mm increases paper cost.

The 3 most common bleed mistakes clients make:

• Bleed not set: the design file edge matches the print size exactly, leaving white edges during trimming
• Bleed set to 5mm: wastes paper and increases cost unnecessarily
• Bleed only on one side: bleed must be on all 4 sides, not just one

Printer recommendation: the printer should check the bleed the moment it receives the design file. Files without bleed should be sent back to the client for resetting.

Preparation 2: Resolution 300dpi

What is resolution? The number of pixels per inch of an image. Printing requires ≥300dpi; below 300dpi the image will blur.

The 4 most common resolution mistakes clients make:

• Screenshot from a webpage: web images have only 72dpi resolution, blurry when printed
• Screenshot from video: video frames have only 72–96dpi resolution, blurry when printed
• Exporting raster from AI software: raster images exported from AI default to 72dpi, must be manually changed to 300dpi
• Mobile phone photos: although phone photos have high resolution (4000x3000), they default to 72dpi output and need to be changed to 300dpi

Printer recommendation: the printer should use AI software to check image resolution upon receiving design files. Images below 300dpi should be rejected and the client should be asked to provide high-resolution versions.

Preparation 3: Color Mode CMYK

What is color mode? Printing uses CMYK (Cyan, Magenta, Yellow, Black); screen display uses RGB (Red, Green, Blue). When a client sends an RGB file, the printer must convert it to CMYK, but the conversion will cause color shifts.

The 4 most common color mode mistakes clients make:

• Sending RGB directly to the printer: the printed color differs from screen display by 10–20%
• Using RGB spot colors: RGB spot colors cannot be converted to CMYK, resulting in incorrect colors
• Using CMYK spot colors without specifying the Pantone number: Pantone numbers are the color standard; without them the printer cannot match colors
• Using RGB black: converting RGB black to CMYK results in "four-color black" — all 4 inks are applied, wasting ink and causing smudging

Printer recommendation: client design files must use CMYK mode. Spot colors must include the Pantone number (e.g. Pantone 1655 C). Black should be single-color black (K 100%), not four-color black (C 100% M 100% Y 100% K 100%).

Preparation 4: Fonts Converted to Outlines

What is converting fonts to outlines? Converting the fonts in a design file to paths/curves, so that any computer can display them correctly.

The 4 most common outline conversion mistakes clients make:

• Fonts not converted: when the printer opens the file, fonts become default SimSun, ruining the entire design
• Some fonts converted, some not: mixed conversion causes inconsistent display
• Text still wrong after outline conversion: some fonts deform after outline conversion and need to be re-checked
• Using non-system fonts: if the client uses non-system fonts (e.g. Hua Kang Jin Wen Ti), the printer's computer won't have that font installed and will fall back to the default

Printer recommendation: clients must convert all fonts to outlines in design files. In AI software, the menu 【Type】→【Create Outlines】 can convert all fonts in one click.

4 Iron Rules for Printers Receiving Design Files

1. Check 4 things the moment you open the design file: bleed / resolution / color mode / fonts converted to outlines
2. Require client revisions if any item fails: don't "make do" — products made reluctantly will be poor quality
3. Quote only after all 4 preparations pass: to avoid repeated revision costs later
4. Print a digital proof for confirmation: after all 4 preparations pass, print a digital proof for the client to confirm color and effect

3 Most Common Composite Mistakes Clients Make

1. Design file crosses boundaries, is blurry, and fonts aren't converted: failing all 3 items is the most common "designer newbie" mistake
2. RGB mode + screen color: clients design in RGB and judge color on screen, resulting in large color shifts when printed
3. Using素材 downloaded online:素材 downloaded online have low resolution and may infringe copyright

4-Item Pre-Press Preparation Checklist

Before sending design files to the printer, clients are advised to use this checklist for self-inspection:

• Bleed: 3mm on all 4 sides? ✓/✗
• Resolution: all images ≥300dpi? ✓/✗
• Color mode: CMYK? ✓/✗ Spot colors have Pantone numbers? ✓/✗
• Fonts converted to outlines: all fonts converted to outlines? ✓/✗

Only when all 4 items are checked ✓ can the file be sent to the printer; otherwise it will be sent back for rework.

Further Reading

• Comparison of 3 Pre-Press File Formats: AI / PDF / CDR — A Real Case of 3 Days of Rework from Sending the Wrong Format
• 3 Types of Printing Accidents Caused by Insufficient File Resolution: The Client's "HD Image" Is Actually Only 72dpi
• Pantone vs CMYK vs Digital RGB: The Real Gap Between 3 Color Gamuts, Told Through the Story of 1655 Orange