Minimum stroke thickness in design
When designing, you often use lines or strokes. You can adjust the thickness or weight of these lines based on your design needs. As you increase the stroke weight, the line becomes thicker, and conversely, decreasing it makes the line thinner.
One issue that can cause problems during preflight and production is using an extremely thin stroke weight. For example, you can set a line as thin as 'Hairline' in CorelDRAW or 0.25 points in Illustrator. But is this weight sufficient for a good print? If not, why is this option even available in the software?
The weight or thickness of a line in design software doesn't necessarily guarantee its accurate reproduction in print. Many design elements are created solely for digital display and aren't intended for printing. It's crucial to adjust file settings based on the specific printing process and material. This means carefully considering factors like the printing machine's capabilities and the paper's characteristics when determining line weight.
Amount of stroke weight
The minimum stroke weight or line thickness should be chosen based on production requirements and in coordination with the printing press. It's clear that unilateral adjustments made by the designer without consulting the production team can lead to issues during printing.
The minimum stroke weight depends on the quality of the printing material, the precision of the printing plate (cliché or plate), and other factors during printing, like cylinder pressure. For instance, some flexography printing machines can't produce a line as thin as 0.25 points on the plate, even if the machine and materials are suitable.
In another scenario, when a file is processed for lithography, the software that converts digital images into halftones might create broken or uneven lines. Consequently, the plate will reproduce these imperfections.
As you've likely realized, factors like stroke weight, ink coverage, and packaging diecut configuration shouldn't be determined solely by the designer without input from the printer. The question then arises: How can printers effectively communicate technical specifications and data to designers?
1. Production manager experience
Basically, the printer who is in charge of production knows best because they've worked with many different printing jobs. Their experience tells them what will and won't work on their machines. However, different printing presses and materials can have slightly different requirements, so the exact numbers can vary from one printer to another. But the differences won't be huge.
2. Create Fingerprint
We've explained this in detail elsewhere, but here's a brief overview. Imagine a printing press that needs to be precisely calibrated. In the process of lithography to printing, all crucial elements like minimum stroke weight, dot gain, ink coverage, and the smallest printable font size are tested and recorded in a production chart for future reference. During this calibration process, a fingerprint file is used. This is a special file containing specific graphic elements that is printed once, just like any other file.
And as a result...
By printing and meticulously analyzing the fingerprint, print production experts can establish a precise minimum stroke weight for the specific printing press, material, and ink combination.
This crucial data, often referred to as the "press profile," becomes a foundational element for future print jobs. It enables printers to optimize settings, reduce errors, and ensure consistent print quality.
The fingerprint process also helps identify potential machine limitations or material incompatibilities that might affect print outcomes. This knowledge empowers both printers and designers to make informed decisions, leading to improved efficiency and higher-quality printed products.
