As digital printing has evolved, a new relationship with offset printing is emerging as well. Individually, each offers different benefits - together they are even more powerful. Offset preprinting brings the benefit of customization to large print runs, like one to one marketing materials or promotional direct mail.
Offset preprinting allows you to minimize costs through the printing of shells (static info) on offset presses, followed by printing variable data on digital equipment. Offset preprinting combines the best of both worlds, providing customized marketing campaigns, reduced costs, and increased response rates for print. Here are a few things to keep in mind to achieve best results when combining both technologies.
• Basis Weight – make sure you know what the recommended paper specs are in terms of weight for equipment you’re using. It is suggested that using a minimum weight of 24/60# paper will optimize your production.
• Coated vs. Uncoated – be mindful if preprinting on coated. The heat from a laser fuser can blister coating which may cause damage to the digital device.
• Finish – textured and embossed finishes may pose a challenge, although some paper manufacturers are now making grades expressly for digital with embossed finishes like linen. A sheet with a smooth, level surface will allow for the even transfer of toner, preventing voids or broken letters.
• Samples – make sure you test the sheet to ensure compatibility on the digital equipment.
• In general, try to format the product so that it can run through the equipment grain long. When ordering folio product – be sure the final form can be cut to this grain direction. This will help in feeding the paper through laser equipment.
• Be wary of large solids or gradients which can cause banding or mottling. Try to use noise or texture to filter out these effects.
• Be mindful of raised surfaces such as letterheads or embossing, they can cause feeding issues and lower print quality.
• Communication is key, talk to your printer to determine compatible inks, techniques and papers for the project and the equipment.
• Specify laser compatible inks that can with stand temps of 350 – 400o - inks should be oil based and heat or thermal resistant. Avoid metallic, fluorescent or cold set inks, which are generally not compatible with laser fusers.
• Keep the ink coverage light. Toner does not adhere to heavily printed offset inks. Also, avoid overlapping laser printed images with offset images. If you have to over print offset ink, use a half tone screen.
• Avoid anti-setoff powders, they can interfere with toner transfer and fusing.
• Make sure the final cut of your form is square and clean – any poorly trimmed paper can cause feeding issues.
Packing & Storing
• Make sure all pre printed materially has ample drying time before its placed in a moisture barrier wrap. In general three days is a pretty safe rule of thumb.
• Maintain 50% humidity to acclimate the paper and minimize moisture fluctuations.
• Use chipboard above and below the paper stack to minimize damage to the edges and corners. Avid packing the material too tightly, it can result in curl.
• Preprinted material should be allowed to acclimate for 24 hrs. at minimum while still inside the moisture barrier wrap. This should be done in the area where the material will be imaged.