Offset printing (also called offset lithography) is one of the most common image-production methods for marketing materials and documents for mass-production. It is a form of mass-production printing in which the images on the metal plates are relocated to rollers or rubber blankets and then to the print media. Metal plates, generally made from aluminium, are used to transmit the image on to a rubber blanket and then roll that image on to the printing paper. The process is called offset printing because the ink is not printed directly on to the sheet of paper, instead, it has to pass through the metallic plates.
During printing, the image to be printed is transferred on to thin metallic plates, dampened with ink and water, via rollers on the printing press. The ink sticks to that part where the image needs to be and the water adheres to any part of the plate that has no image. The inked image is transferred to the rubber blanket cylinder and then on to the paper. The press system prints on both sides of a sheet of paper in a single process.
Below are some of the advantages of offset printing:
- Offset printing produces sharp and clear images.
- The colour reproduction is crisp and accurate.
- Offset printing works on a wide variety of printing surfaces.
- It is more cost-effective than any other form of printing.
- It is very quick.
On the other hand, there are several drawbacks of this system:
- Offset Printing is time-consuming and requires a large quantity of ink.
- Offset printing is less feasible in graphic designing.
- Offset printing has slightly low image quality as compared to rotogravure printing.
Factors influencing quality in Offset Printing:
In offset printing, the final print quality does not depend on a single factor. There are a number of factors which may influence the final print results. All necessary components like the printing plates, ink and substrate have a considerable impact on the final shots. Some of the factors linked with the printing press are listed below:
- Register-defined printed image
To get the most precise printing results, it is important to align the metal plates and ink in the production units to ensure register accuracy during the printing course. The image that needs to be printed must remain in the exact same position throughout the run, otherwise, register differences may result in colour variations.
- Colour Fluctuations
Offset printing is more prone to such variations than any other printing method, because of the many factors that can affect the balance between the damping medium and ink. Hence, to get the best quality image, colour fluctuations during a production run must be minimised.
- Low Dot Gain
Low Dot Gain is a common problem with offset printers; in which the printed material looks darker than it was originally intended to be. Hence, dot gain should be kept at the minimal level to get the maximum range of tonal value. Naturally, all the materials including ink, rollers, metal blankets, printing plates and substrate play an important role in minimizing the dot grain. To reduce it, ensure the correct unrolling of cylinders, optimise the printing press adjustment and set the rollers precisely.
If you need to a large number of products printed within a short period of time, offset printing in Singapore should be your first consideration.