2, direct plate method failure and reasons.

(1) Loss of photosensitive film during development cannot be achieved

A, caused by insufficient exposure, should extend the exposure time.

B. Insufficient or invalid dose of sensitizer caused by reduced sensitivity. Should add more sensitizers, but not excessive, excessive pinholes will be generated.

(2) The full-page image produces a pale ash.

A. Due to the over-brightness of the work place where the photosensitive liquid is applied and dried, it is necessary to perform work under a yellow light.

B. Due to the lack of positive film density, a higher density positive film should be used.

C. If the positive film density is normal, it is caused by too long exposure time, and the exposure time should be reduced.

D. Because of the overheating caused by the application and drying of the photosensitive liquid, it should be replaced by cold air.

E. Due to insufficient exposure time and insufficient development, the exposure time should be extended, and sufficient development should be performed. The excess water on the layout should be quickly removed with a sponge or absorbent paper for drying.

(3) The subtle part of the image is not developed:

A. The reason is that the exposure time is too long.

B. The positive and negative sides are reversed, and the positive film is poorly attached to the photosensitive surface.

C. The prevention of scattering from the screen is insufficient.

D. The photosensitive film is too thick and the type of the photosensitive liquid is not properly selected or the photosensitive liquid is invalid. It is best not to use a high-temperature light source to prevent emulsion hardening.

(4) If there are a lot of bubbles in the coated screen plate, the reason is:

A. Whether the screen degreasing treatment is sufficient.

B. Whether the screen cleaning before coating the photosensitive adhesive is clean.

C. During the coating process, pay attention to whether the temperature difference between the screen drying and the photosensitive adhesive is large.

D, whether the storage temperature of the photoresist is too high.

E, photosensitive adhesive and coating layer is too thin.

F, coating speed is uniform.

(5) There are too many pinholes in the layout. The reason is:

A. Dust is the main cause.

B. Sometimes it is caused by the bubbling of the photosensitive liquid itself.

C. When using a coating scraper, the coating scraper moves too quickly and it is easy to blistering to produce pinholes.

D. Adding excess photosensitizer can also produce pinholes.

E. The coated surface is very easy to get dusty. Therefore, it is necessary to keep the workplace clean. For example, the surface of the printing glass, the surface of the positive printing sheet, and the coated surface of the photosensitive liquid must be kept completely clean.

F, can add a small amount of octanol as a defoamer in the photosensitive liquid.

(6) If the screen plate shows obvious air holes after development, the reason is:

A. Whether high temperature drying is performed after the development (this should be noted).

B. Whether a sensitizer with a long shelf life was used.

C. Is there any dust in the photoresist?

D. Whether the sensitizer and the emulsion are mixed with sufficient stirring, whether it is used after the bubbles have disappeared.

E, to grasp the exposure time is appropriate.

(7) If the graphic resolution is not high after printing, the reason is:

A. Whether the development is sufficient; whether it is flushed with clean water after development.

B. The screen for secondary use has been cleaned before use.

C. Whether the screen is in a horizontal position and dry.

D. Whether to use a high-sensitivity photopolymer.