7 Common Flat Screen Printing Problems and How to Solve Them

Flat screen printing is one of the most famous methods used in different industrial sectors. For example, textiles, promotional products, signage, packaging, labels, industrial components, and many other applications use it for printing purposes. Like many other methods, it can encounter issues with the screen, stencil, ink, squeegee, substrate, or printing conditions.

There can be several common issues. We have discussed the top seven common issues and explained how you can resolve them. Let’s look at them in detail.

Uneven ink coverage causes irregular printing. Some areas appear darker and thicker while others may have a small quantity of ink and appear lighter. It often occurs during the printing process or under the conditions in which it occurs.

Common Causes

There can be several causes of the uneven ink coverage listed as follows:

• ​Incorrect squeegee pressure
• Inconsistent squeegee speed
• Uneven squeegee angle
• Incorrect ink viscosity
• Poor screen tension
• Insufficient ink on the screen
• Inadequate flooding
• Uneven substrate surface

Solutions

A standard squeegee operation is crucial for consistency in printing and the right printing steps. Here are a few solutions in this case.

• ​You should consider and maintain consistent squeegee pressure.
• Ensure the squeegee angle remains stable during the stroke.
• Always keep a consistent printing speed.
• The screen should have appropriate and uniform tension.
• Make sure there is an adequate amount of ink on the screen.
• Use a proper flood stroke before printing.

Sharp edges are essential when printing logos, small text, patterns, or detailed graphics. Sometimes, blurred or fuzzy print edges disrupt the overall print pattern and make the graphics look odd or slightly invisible.

Common Causes

There can be a few causes of blurred or fuzzy edges, as follows.

• Excessive squeegee pressure
• Incorrect off-contact distance
• Poor screen tension
• Low-quality stencil
• Excessively thin ink
• Screen movement
• Ink bleeding
• Poor substrate positioning

Solutions

You should check the relationship between the screen and the substrate. Here are a few typical solutions implemented in this case.

• Don’t apply excessive squeegee pressure.
• Check the off-contact setting.
• Ensure adequate tension of the screen.
• Inspect the stencil for damage or poor exposure.
• Use ink with the correct viscosity.
• Secure the substrate properly.
• Check the screen for movement during printing.
• Avoid excessive ink deposition.

Have you noticed pinholes and small unwanted dots during the printing process? They occur for several reasons; for example, dust particles can obstruct ink coverage.

When the printing area is large, dots may appear noticeable.

Common Causes

Here are a few typical causes of such issues.

• Dust on the screen
• Dirty working environment
• Grease or oil contamination
• Poor emulsion coating
• Inadequate screen exposure
• Air bubbles in the emulsion
• Damaged mesh
• Contaminated substrate

Solutions

Proper cleaning and preparation of the screen mesh are essential. Here are a few typical solutions in this case.

• Clean and degrease screens properly.
• Work in a clean environment.
• Inspect the screen before printing.
• Verify exposure settings.
• Remove dust and contamination before printing.
• Repair minor stencil defects before production.
• Replace screens with severely damaged mesh.

Color alignment is essential for accurate printing and performance. When colors don’t align properly, unwanted color shifting occurs, creating gaps, overlaps, or outlines.

In such a case, you should focus on ensuring proper registration.

Common Causes

The typical causes of such issues are:

• Incorrect screen positioning
• Loose screens
• Movement of the substrate
• Poor registration marks
• Inconsistent substrate placement
• Machine calibration problems
• Changes in substrate dimensions

Solutions

The possible solutions are:

• Use accurate registration marks.
• Align each screen carefully.
• Secure screens firmly.
• Keep substrate positioning consistent.
• Calibrate the printing equipment.
• Check for movement during the printing stroke.
• Perform test prints before production.
• Inspect registration periodically during long production runs.

Ink smearing and blotting can distort the whole design structure. It often occurs after printing and handling.

Common Causes

The typical causes of ink smearing and blotting include:

• Insufficient drying time
• Incomplete curing
• Excessive ink deposition
• Incorrect ink-substrate combination
• Improper stacking
• High humidity
• Incorrect curing temperature
• Slow-drying ink

Solutions

A few solutions are discussed below.

• Allow sufficient drying time.
• Verify curing temperature.
• Confirm curing or dwell time.
• Avoid stacking freshly printed products.
• Avoid applying excessive amounts of ink.
• Use an ink suitable for the substrate.

Ink adhesion issues occur when the ink doesn’t adhere to the substrate, resulting in poor design printing. It can cause issues such as scratching, peeling, cracking, flaking, or washing away during use.

Common Causes

Here are a few common issues for poor ink adhesion.

• Incorrect ink selection
• Dirty substrate
• Oil or grease on the surface
• Insufficient curing
• Incompatible surface coating
• Poor surface preparation
• Incorrect ink-substrate combination

Solutions

The typical solutions are:

• Identify the exact substrate material.
• Select an ink designed for that substrate.
• Clean the surface thoroughly.
• Remove oil, grease, dust, and other contaminants.
• Use primer when required.

When ink begins to dry and accumulate in the mesh openings, it clogs the mesh, causing poor printing. Poor ink flow often causes such issues and blocks the printing process. You should confirm and apply printing solutions.

Common Causes

Here is the list of common issues.

• Ink drying inside the mesh
• Incorrect ink viscosity
• Long production interruptions
• High temperature
• Low humidity
• Unsuitable ink formulation
• Insufficient flooding

Solutions

There are a few common solutions, such as:

• Maintain the recommended ink viscosity.
• Use proper flooding techniques.
• Avoid unnecessary interruptions.
• Keep the printing environment within suitable conditions.
• Prevent excessive heat around the printing area.
• Clean the screen when required.

The quality of printing through the flat screen depends on the screen, stencil, ink, squeegee, substrate, machine settings, and working environment. Any issue that often occurs involves all these steps and printing components.

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