Offset Printing FAQs: Answers to All Important Questions
Offset printing is one technology that you can rely on for high-quality mass production in a shorter span. It is one of the oldest methods, dating back to 1875. Despite the prevalence of digital printing, many businesses still use it, for example, in direct mail marketing. This is because its benefits outweigh contemporary methods. For instance, it provides more detailed and vibrant images than its digital counterparts. However, despite this, companies have many questions about it. This blog will cover common printing offset FAQs to help you understand the technology.
Key Takeaways
- Offset printing involves transferring ink from a plate to a rubber blanket and then to a medium.
- It is ideal for high-volume printing jobs where quality and cost are essential.
- It has four categories, each serving a different purpose. Web printing is suitable for mass production, but sheet-fed printing is appropriate for small jobs.
- Unlike digital printing and flexography, offset printing produces high-quality images and is highly adaptable across multiple applications.
What is Offset Printing?
It is also called lithography, offset lithography, or litho-offset and is one of the most sought-after printing methods used for various applications, including direct mail marketing. It involves using a sequence of rotating cylinders to transfer ink to receiving media such as paper, wood, cloth, or leather. Unlike other methods, it does not transfer ink onto the printing substrate. Instead, it moves into the rubber cylinder and then delivers it to the paper or other media, hence the name. This three-step process reduces the wear and tear of the printing place, thus extending its lifespan.
What Type of Ink is Used for Offset Printing?
Typically, you use an oil-based ink in this process. It consists of three ingredients: pigment, vehicle, and modifiers. The pigment is the colouring material, and the vehicle is a liquid that holds the pigment and carries it to the medium. The modifier is an element that is added to the ink to control drying, fading, smell, resistance, and scuffing. Earlier, manufacturers made this ink from petroleum, but now it uses soy-based products, which give precise colours. It is also recyclable, as you can easily remove the ink during de-inking.
What Are the Steps Involved in Offset Printing?
Image Preparing
This involves creating a plate for each colour present in your design. You can make them from metal or polyester. You can chemically etch the text or image that you want to print on them. Each plate corresponds to a single colour in the final print, such as cyan, magenta, yellow, and black. This method prints one colour at a time; hence, the operator adjusts colour groups per printer to produce a correct and sharp image. This involves maximizing the cyan hues while reducing the shades of yellow.
Ink and Water Separation
Oil-based ink and water don’t mix; hence, the system has separate rollers for both. The printing plates also have dedicated areas that attract water and ink. The tool applies ink to the image area of the print while repelling the non-image area with water. This separation helps maintain clear and precise prints.
Transfer to Blanket Cylinder (Initial Offsetting)
A blanket cylinder is a roller that has a rubber covering. After separating the ink and water, the tool transfers the image to this cylinder. This prevents the picture from directly touching the paper, ensuring consistency and even pressure during printing. The tool has a unique vibrating roller. When it comes in contact with the wet plate, the ink sticks to the untreated part.
Transfer to Paper (Final Offsetting)
Air jets will push the paper automatically to the printer to automate the process. The blanket cylinder will meet the paper and transfer the inked image. The paper will absorb the ink, leading to a printed image.
Drying
The paper goes through drying units and racks to prevent unwanted moisture and set the ink. This helps prevent smudging and ensures the print material is ready to finish. After this, you can add a matte or glossy coating to give it an appealing finish. You can then fold, collate, bind, and add perforation to the paper per your requirements.
What Are the Types of Offset Printing?
Web
It involves continuously feeding rolls of paper through a high-speed press. The tool transfers the ink on a series of rollers before applying it to the paper as it moves quickly through the machine. Due to its rapid speed and efficiency, businesses use it to produce newspapers, magazines, and catalogues.
Sheet-Fed
This process involves passing a single sheet of paper through the press at a time. The operator loads precut sheets into the press, which the machine guides through rollers and cylinders. There are two types of cylinders in this process: plate and blanket. The plate cylinder carries the metal plate, which transfers ink to the blanket cylinder. The blanket cylinder then presses the ink on the paper. This process is suitable for smaller runs where detail and clarity matter.
UV
It uses specially formulated ink containing photo-initiators that react to UV light. When the sheet passes through the press, the UV lamp instantly presses and dries the ink, giving it a smudge-resistant finish. This process speeds up production and is helpful in time-sensitive projects.
Waterless
Instead of using water and ink-resistant areas, this method uses silicone plates, which repel ink from non-image areas. Since there is no interference by water, the images are sharper and more vibrant. Additionally, it helps the environment by minimizing water usage and chemical waste, which the standard method generates.
How is Offset Printing Different From Other Methods?
Digital Printing
It involves directly printing digital images on various media substrates without plates. However, ensuring accuracy requires specialized technology, printing software, ink, and calibration tools. The table below shows how it is different from offset printing.
| Parameters | Offset Printing | Digital Printing |
| Resolution | It works at a higher resolution, typically above 2400 dpi. The traditional method of transferring ink from the plate to the rubber blanket and applying it to the desired surface prints intricate, sharp images with vibrant colours. | Digital printing presses operate at a lower resolution, i.e., 1200 dpi. The images are not sharp, and the colour accuracy will be low. |
| Ideal For | As the volume increases, the per-piece cost of printing decreases. This method is suitable for high-quantity jobs because the installation cost spreads over many prints. | It is economical for low-quantity printing jobs as it does not require plates or manual adjustment and can start the work almost instantly. However, since it uses specialised toners and ink, the cost per piece increases as the volume increases. |
| customisation | It is efficient for large batches of identical prints, as personalization would require setting up separate plates for each variation. However, it is labour-intensive and expensive for custom prints. | It allows variable data printing, where you can change the design element of each piece directly from the digital file and instantly send it for the job. |
Flexography
It involves using a flexible relief plate to print on various substrates. There is a polymer plate wrapped around a rotating cylinder to create colours. The plates raise the images and texts of each colour; hence, only those parts receive ink. The table below will show why you should prefer offset over this technique.
| Parameters | Offset Printing | Flexography |
| Resolution | It provides higher-resolution prints (up to 2400 dpi), which create highly detailed images with fine lines. | It works on lower resolutions (150 dpi to 200 dpi). The images are less precise, and there is noticeable pixelation. |
| Versatility | They can be used for different materials, textures, and shapes, whether a brochure, business card, notebook, or packaging. | It is only suitable for packaging and labels, especially on non-porous surfaces like plastic and corrugated cardboard. |
| Consistency | It can print high-quality prints without any variation throughout the run. This ensures uniformity across thousands of copies. | The colours may vary, especially with different substrates and intricate designs. The variation is prominent on non-absorbent materials. |
What Are the Benefits of Using Offset Printing?
High-Definition Quality
It produces sharp images with vibrant colours. Since the process involves transferring ink from the plate to the paper, the photos are accurate and consistent in colour regardless of the quantity. Printing operators can configure the setting to achieve desirable results.
Lower Cost
Compared to other printing methods, it has a low setup fee. After the setup, you can print as many materials as you want. The price per print will fall as the number of orders increases. This makes it ideal for small businesses that want to execute direct mail marketing strategies on a mass scale without breaking the bank.
Additionally, earlier, each print would require a customized plate, which made the process costly. However, with the latest technologies, making the plates is cost-effective, and you can use one piece many times, further reducing the cost.
Prints on Any Surface, Material, or Shape
The rubber blanket used in this technique allows you to print on different textures and shapes. You can print on plastic bottles, labels, and round containers without issues. You can also print on any material, such as metal, paper, wood, and fabric. You can also use it to print on glossy and matte finish papers and light-weight or heavy cardstock.
Sustainable
As mentioned, it uses vegetable- and water-based ink, creating biodegradable printing materials. Moreover, the cylinder’s aluminum plates directly contact the rubber blanket instead of abrasive and coarse material like cardstock or wood, making them last longer.
Fast Turnaround Time
Its efficient setup and quick-drying ink enable faster production than other methods. Another feature that leads to quicker turnaround time is the web figure. This method continuously feeds the paper roll through the press, which speeds up the printing. This is especially advantageous when the requirement is high and time-sensitive.
Where is Offset Printing Used?
Schools
They need books and magazines in large quantities while maintaining consistency and cost-effectiveness. Offset printing helps generate high-resolution images and texts with precision. It helps make the colours pop and sharpen the image, thus enhancing the visual appeal.
Direct Mail Marketing
It is ideal for creating postcards, brochures, letters, and other collateral, especially for small businesses on a limited budget. Its ability to reproduce consistent colours makes it the right choice for maintaining brand identity through printed materials.
Newspaper
News houses print newspapers in large quantities. Offset printing efficiently and cost-effectively handles this. It offers the speed and quality publishers can use to meet daily requirements while ensuring readability and clarity in the text and images.
Packaging
This printing technique generates high-quality boxes, labels, and cartons. It ensures that the box’s intricate designs, logos, and images come out with exceptional clarity and colour fidelity. This is especially important in industries like cosmetics and electronics, where appealing packaging can significantly affect branding.
Get Support for Every Printing Technique With PostGrid
Offset printing remains a top-notch choice to create superior quality and cost-efficient materials, whether a direct mail marketing piece, a newspaper, or a magazine. However, businesses today need flexibility, and this is where PostGrid Print & Mail API can help you. Whether you need to fulfil high-volume jobs through offset or digital printing for on-demand personalization, we have you covered. With automation, we will help you print and ship various collaterals like postcards, letters, etc., regardless of scale or complexity. To know more about our solution, talk to our sales team today.
