» Common problems and causes in screen printing

There is no ink on the surface of substrate (uneven ink leakage), the reason is:
1. The mesh number of the screen is too high, and the ink permeability is poor.
2. The sensitive film is too thick and the ink permeability is poor. .
3. There are scars on the blade of the rubber scraper. .
4. The pressure of the rubber scraper is not enough or uneven. .
5. The gap between screen printing plate and substrate is too large. .
6. Ink viscosity is too high and penetration is low. .
7. The ink return rubber scraping is uneven. .
8. The printing speed is too fast, which makes the ink supply uneven.
There is too little ink on the screen.
After printing, the ink seeps oil, resulting in edge shadow or virtual shadow, blurred image and text. The reasons are as follows:
1. The edges and corners of the blade of the rubber scraper are worn, and the effect of ink breaking in the rubber scraper is poor.
2. The printing angle of rubber scraping is too small, resulting in excessive ink supply.
3. The viscosity of the ink is too low, and the ink will flow through after printing.
4. Uneven mixing of ink and solvent causes the ink with more solvent to penetrate after printing.
5. After cleaning the silk plate, there is residual solvent.
6. The screen printing plate and substrate overprint rules are in error.
7. Improper selection of ink and screen mesh, fine ink and too low screen mesh.
8. Pause or repeat in the process of silk screen printing.
9. When returning ink, the rubber scraping force is too large. When not scraping, a small amount of printing material has extruded out of the mesh.
Causes of mesh blocking:
1. Substrate is not smooth or low strength, off powder, hair caused by blocking.
2. The pigment and other solid particles in the ink are large, so it is easy to block the mesh during screen printing.
3. High temperature, low temperature, fast volatilization of solvent in the ink, high viscosity, causing blocking, or long downtime, also easy to cause blocking. Low temperature, poor ink liquidity, but also easy to create blocking.

4. Screen printing plate placed for a long time, cleaning before printing, adhering to dust, resulting in blocking.

5、 When scraping, the pressure is too high, and the bending degree of rubber scraping is too large, resulting in the surface contact during scraping.

6. The screen plate can not be separated from the substrate after scraping. When lifting, the printing surface of the plate adheres to the ink, which is easy to be blocked.

Plate making is the pattern part with ghosts.

There are burrs and sawtooth on the edge of the picture and text. The reasons are as follows:

1. Sensitive glue resolution is not high, resulting in fine lines broken or incomplete.

2. Screen printing plate exposure insufficient or too long, development will appear burr (sawtooth).

3. Screen printing plate printing surface is not smooth, there is a gap, when scraping, ink overflow, resulting in burr.

4. The original film is not good.

5. The angle of tension is improper.

The mesh number of the screen is too low, so there is burr in plate making.
After screen printing, the ink and substrate are not firmly bonded, resulting in the following reasons:

1. The surface of substrate is not clean with oil, dust, etc., or plastic products are not fully treated before printing.

2. The adhesive force of the ink itself is not strong. In this case, other kinds of ink should be replaced.

3. Improper selection of diluent.

4. Ink expired.

5. The net distance is too large.

Improper addition of additives.
The causes of air bubbles on the surface of finished silk screen ink:

1. The speed of rubber scraping is too fast or the drying is too fast.

2. The ink itself has bubbles or uneven mixing.

3. The screen is polluted.

4. The substrate surface is not clean or greasy.

The reason why the screen ink layer is too thick:

1. Mesh count too low.

2. The squeegee is too soft or the cutting edge is too round.

3. The squeegee angle is too small.

4. Too much ink is placed on the Internet.

5. The pushing pressure of the rubber scraper is improper.

6. Screen printing plate film thickness is too thick.

7. The speed of rubber scraping is too slow.

The reasons for the enlargement of the size of image and text of screen printing products:

1. The viscosity of the ink is too low.

2. Ink liquidity.

3. The wire mesh tension is too low.

4. The pressure of the rubber scraper is too high.

The reason for the screen mark on the imprint is that the ink has low fluidity and dries too fast

1. Choose a more liquid ink.

2. Use the ink with slower drying speed, or add some efficient slow drying agent into the ink.

3. When making screen, try to use single wire mesh with thin wire diameter.



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