Offset Printing Explained
Known as one of the most common flat printing techniques, offset printing is a unique combination of art and science. Simply put, it is a process wherein ink is transferred from a plate to a rubber blanket, then back to the printing surface. While the process can be really technical (hence, the science part), the person operating the press (applies artful skill) also plays a significant part in delivering the desired outcome of the printed piece.
It’s no secret that the digital age has enjoyed tremendous success, yet, print media remains as popular and as in demand. At Rex 3, direct mail is used in advertising daily through the development of flyers, posters and brochures in our fulfillment center. These types of large paper printing jobs would be nearly impossible without offset printing.
The Printing Process
Step One: Make sure you have very well-prepared files. “Print-ready” files have specific requirements like CMYK colors and bleed margins. Submitting a file for offset printing that does not include your printer’s specifications may result in delays or additional costs to convert or redesign the files to the correct specifications. Often, information to help you properly prepare files and avoid unplanned pre-press costs as well as other trouble spots can be found on the printer’s website.
Step Two: A proof is prepared based on the final files. As the name implies, the proof is a tool to verify the quality and accuracy of the printed piece prior to plating and beginning the print run. This is a critical step in the process, assuring that no errors make it to press. Signing the proof is final approval to run the job. The proof will be made full frame, meaning colors and images will go beyond the printable borders or cut lines out to the bleed margins. This is standard. Check colors, text, spacing, fonts, logos, images, everything. The approved proof is kept as part of the official file.
Step Three: After the proof is approved, plating is next. Metal plates in each color are made that get “hung” on the press. Colors include: Cyan, Magenta, Yellow, and Black – CMYK – to make four color process, or any Pantone Color for a single color job.
Step Four: The correct size and paper stock is then loaded into the offset press. The size and scope of the project determines the length of the run—it can be as quick as 30 minutes or as long as multiple days. Knowing how long a print run will take is essential for optimal project management. Allowing adequate time to design, amend, approve, and complete the print run can mean a smooth-flowing project with less stress that is delivered ontime and on budget.
Step Five: The bindery stage is next. Many options exist which includes die cutting, scoring, stamping, numbering, folding, stitching, etc. Since ink and finishes need to dry before a job can be completed, this could turn into a multi-day process. Another note for project planning.
Step Six: Delivery time! The final product is ready to be boxed and shipped to the client.
When it comes to quality, offset printing typically produces more consistent prints, as long as the printers are handled by experienced personnel. The true skills of professionals cannot be overlooked in this process that combines art and science, advanced machinery and hands-on experience. Rex 3 has several decades of expertise in sheet-fed offset print jobs and is home to the SuperPress, the most advanced offset press available today and the HP Indigo 7900, the latest in digital printing technology.