When you create version 1.3 PDF, white lines might be visible in the PDF. White lines are likely to be a display issue in Acrobat. Here are some conditions that can cause this.
• Spot colors can cause the white lines to print if file is used in a 4 color workflow. All spot colors need to be converted to 4 color process.
• White lines can also appear if an image file behind objects or text that have transparency applied, including drop shadows. This tech note is based on Knowledge Base Tech Note (kb403359) from Adobe’s web site.
Here are a few reasons that “White Lines” may appear.
• White or dark lines might appear in areas where process colors and spot colors interact during flattening.
• You might have an image file behind objects or text that have transparency applied, including drop shadows.
IMPORTANT: All spot colors must be converted for 4 color process workflows.