Silk Screened Glass service

When printing on glass, it is very important to conduct a strict degreasing (pre-treatment) inspection before printing. Grease, adhesives, dust, and other substances that adhere to the glass surface will cause poor adhesion between the ink and the glass.
The ink itself is not strong enough to firmly fix the ink film. It is best to use other types of ink for printing. Improper selection of dilution solvents will also cause the ink film to be weakly fixed. The properties of the ink should be considered when selecting dilution solvents to avoid the phenomenon of weak adhesion between the ink and the glass.

There are several causes for uneven ink film thickness. From the perspective of the ink itself, improper formulation can result in inconsistent application. Additionally, even if the ink has been prepared correctly, dried ink skins or contaminants can negatively affect the film’s uniformity. Using solvents can cause the screen mesh to swell and soften during the printing process. This swelling can block the mesh openings, typically allowing ink to pass through. Consequently, the ink cannot transfer smoothly, leading to irregular thickness of the ink film.

Several precautions must be taken to prevent issues related to uneven ink film thickness. First, it is important to filter the prepared ink—especially older ink—through a mesh before use to ensure that any dried ink skins or impurities are removed. Additionally, when reusing previously employed screens, all residual ink attached to the screen frame must be thoroughly cleaned. After each printing session, cleaning the screens and related tools, such as squeegees, is crucial to maintaining their condition for future use.
When printing on glass, damage to the sharp edge of the return ink blade can cause streaks in the direction of the blade’s movement, resulting in uneven ink application. To avoid this, the blade’s edge must be well protected and kept free from damage. If any damage occurs, the blade should be carefully polished with a grinding machine to restore a smooth edge.

Furthermore, the evenness of the printing table can significantly affect ink distribution. Uneven surfaces can cause the ink film to vary in thickness, with raised areas producing thinner ink layers and the recessed regions producing thicker ones. This phenomenon is another form of uneven inking. Additionally, dust particles on the back of the glass or the surface of the printing table can also contribute to such defects. Therefore, maintaining a clean, level printing surface and a dust-free environment is essential for achieving consistent ink application.

① Dust and foreign matter attached to the plate. When making the plate, some souls will be mixed during water washing and development. In addition, during the emulsion coating, dust will be mixed in, and pinholes will be formed when it is attached to the screen. These can be discovered and repaired in time if you pay attention to the inspection during the test. If Dust and foreign matter are attached to the screen, they will block the screen opening and cause pinholes. Before formal printing, carefully check the screen and remove the dirt on the plate.
② Washing the glass surface. The glass plate should be pre-treated before printing to clean its surface and then printed immediately. If the glass is not printed immediately after treatment, it will be contaminated again. After pre-treatment, dirt such as grease can be removed, and at the same time, Dust attached to the surface can also be removed.
③. Pay special attention to your hands when carrying the glass. Fingerprints will also adhere to the printing surface and form pinholes during printing.

Bubbles in the Ink: Bubbles can be introduced when solvents and additives are added and mixed during the ink preparation. These bubbles may dissipate naturally over time if the ink has a low viscosity. However, in high-viscosity inks, some bubbles may not escape easily. While some bubbles might break naturally during the transfer process of printing, others may become larger and more problematic. To address this, defoamers can be added to the ink. The typical defoamer used is around 0.1% to 1%, but excessive use can have the opposite effect and worsen bubble formation. Even when bubbles are present, using ink with the correct viscosity and good levelling properties can help achieve a smooth and flat ink film. If bubbles are not adequately removed and remain in the ink, they can create an uneven, crater-like surface on the printed film.

Fast Printing Speed: Printing excessively high speeds can result in uneven ink distribution and bubble formation. To mitigate this, it is advisable to lower the printing speed to improve the uniformity and quality of the ink film.

If none of these measures effectively eliminates the bubbles from the printed product, it may be necessary to consider using a different type of ink that is less prone to bubble formation. Properly managing these factors will help achieve a flawless and smooth printed surface on the glass.

Use Inks with Good Leveling Properties: Selecting an ink with high flow and levelling capabilities can help ensure the ink spreads evenly after being printed, filling in any mesh marks and creating a smooth surface.

Opt for Slower-Drying Inks: Using slower drying speed allows the ink to flow and level out before solidifying. This extended flow time helps the ink fill in mesh marks and cure naturally.

Use a Fine Mesh Screen: When preparing the screen, it is advisable to use a finer single-thread mesh. Finer mesh screens produce less pronounced web marks, making it easier for the ink to flow and cover any residual patterns.

Applying these techniques reduces the risk of web marks, resulting in a high-quality, smooth ink film on the glass surface.