Offset printing, which is commonly referred to as lithography, is one of the good employed printing methods that enables the production of top-notch printed materials. In this technique, ink is transferred from a metal plate to a rubber blanket. Subsequently, onto the printing surface. The term “offset” signifies that the ink isn’t directly applied onto the paper or substrate but instead goes through a surface before being applied.
Offset Printing Process Overview
CTP Plate Preparation
The first step in the printing process is to transfer the desired image onto a metal plate. This is typically accomplished using either a method or computer to plate technology. To ensure ink distribution specific areas that need to attract ink are made water-repellent (hydrophobic) while the parts that do not form the image are made water-attracting (hydrophilic).
Inking the CTP Plate
The plate is moistened with water. Then ink is applied to the areas containing the image. The ink sticks to the image areas while the non-image areas repel the ink because of the water film.
Transfer to the Blanket
Afterwards the inked image, on the CTP plate is moved onto a rubber blanket. The blanket adjusts itself to match the surface of the material being printed on.
Transfer to the Substrate
Lastly, the image that you want to print is transferred from the blanket to paper or another printing surface. This indirect transfer method helps to ensure a clear image.
Types of Offset Printing
Offset printing can be categorized into types depending on variations, in the printing process or equipment employed. Some known forms of printing comprise;
Sheet-fed Offset Printing
In printing using sheet-fed machines, paper sheets are loaded into the printing press individually one, at a time. This method is mostly ideal for doing print with quantities. This method offers great versatility in terms of paper dimensions and varieties.
Web Offset Printing
In web offset printing the printing press feeds a roll of paper. This type of technique is mostly used for printing newspapers, magazines, and catalogues in quantities. It is faster and runs at less cost for extensive print jobs.
Coldset Printing
Coldset printing or non-heatset printing is a method of web offset printing that enables the ink to dry naturally by being absorbed into the paper. This special type of offset printing is frequently used for newspaper production.
Heatset Printing
Heatset printing is a type of web offset printing where the ink gets dried using air force. This results in drying times making it ideal for producing high-quality color prints on coated papers, like magazines.
UV Offset Printing
UV offset printing utilizes ultraviolet (UV) light to cure or dry the ink enabling the printing, on substrates and delivering vivid colors. Verily this method is commonly employed for premium applications and packaging purposes.
Waterless Offset Printing
Waterless offset printing is a method that eliminates the requirement for dampening solutions through the utilization of a printing plate coated with silicone. It is good enough for the production of images to reduce waste and have an impact on the environment.
Variable Data Offset Printing
Variable data offset printing involves integrating content like customized text or images into the printing procedure. This is frequently seen in the creation of mail-personalized marketing materials and transactional documents.
Offset Printing VS. Digital Printing
Offset printing and digital printing are two types of printing methods each having their unique features and benefits. Let’s take a look at some variations, between offset printing and digital printing;
| Offset Printing | Digital Printing | |
|---|---|---|
| Printing Process | It includes the transfer of ink from a metal plate onto a rubber blanket and then onto the printing surface, typically paper. | Digital printing involves transferring files directly to the print material, using toner or inkjet technology. |
| Setup Time | The setup for offset printing takes longer due to plate creation and press adjustments, ideal for large print runs. | Digital printing has a faster setup time as it requires no plates, suitable for small, on-demand runs. |
| Costs | Offset printing is cost-effective for large quantities but expensive for small runs due to higher setup costs. | Digital printing is more affordable for short runs but higher per unit for large quantities. |
| Print Quality | Offset printing is known for its consistent, high-quality images and color accuracy, especially with Pantone colors. | Digital printing has improved but may not match offset printing for color accuracy and fine details. |
| Variable Data Printing | Offset printing is not ideal for variable data printing, where individual items need customization. | Digital printing excels in variable data printing, allowing easy customization of text and images. |
| Substrate Compatibility | Offset printing supports a wide variety of papers and cardstocks. | Digital printing supports a variety of materials, but offset printing still offers more flexibility. |
Offset Printing Machines
Every printing machine that we are going to mention has its own specifications. While serving for specific purposes, within the field of offset printing. Let me provide you with an overview of each one;
Solna 125 Plus
The Solna 125 Plus is a printing press that uses sheets of paper and offset technology. It is specifically built for printing on a medium scale. The “Plus” in its name implies that it offers features or enhancements compared to the Solna 125 model. Also has the ability to handle paper sizes. Produce excellent print quality. Solna 125 Plus main applications include printing magazines, catalogs, brochures, and other materials used for purposes.
Roland 28*40 and 25*38
The mention of “28*40” and “28*38” probably refers to the sheet size that these Roland offset printing presses can accommodate. The type of machines belong to the Roland 700 series, which is known for their automatic features with fast printing speeds, and precise output. While it is important for the printing industry who want to handle large-scale printing tasks. Have the capability to process various types of materials. In the end, these printers find applications in producing packaging materials, promotional items, and publications of quality.
Half Rota or Rota
“Half Rota” and “Rota” are likely terms used in the printing industry to describe web offset printing presses. Web offset presses differ from presses as they use rolls of paper or individual sheets. Specially, used for high-volume printing purposes such as newspapers, magazines, and catalogues. The term “Rota” may indicate a full-scale web offset press while “Half Rota” could potentially refer to a smaller version of the same press. And also maintaining consistent quality.
GTO (Heidelberg GTO)
The Heidelberg GTO (Goss Toyoda Original) is widely recognized as a favored choice, among sheet-fed offset printing presses. Renowned for its dependability, flexibility, and user-friendly interface the GTO series encompasses models that are commonly used for short prints. However, this is good for fulfilling the needs of commercial items such as business cards, letterheads, and smaller-scale publications.
Advantages
- High-quality prints
- Cost-effective for huge print quantities
- A good quality of images is crucial for qualitative work like for magazines, brochures, and packaging
- As the print volume increases the unit cost decreases.
- An economical choice for large-scale production
- Color control through Pantone color matching ensuring brand consistency
- A wide variety of paper options
- Flexibility to printers and designers, in their decisions
Disadvantages
- The extended setup time
- Higher initial expenses
- Creating printing plates
- Making press adjustments demands time
- Resources rendering it less efficient for short print runs or on-demand printing needs
- During the setup and make-ready process offset printing tends to generate waste
- Remains the option for high-volume print jobs that require quality and color precision
