Reflective densitometer in the PC version of the quality of the test are mainly used in the following categories: Plate base density measurement of the measurement of the base density of the test, is to test the effectiveness of electrolytic ash removal ash. The measured value is too high, that is, the layout color is too heavy, indicating that the removal of ash is not complete; the measured value is too low, that is, the color of the layout is excessively white, indicating excessive ash removal. As the ash removal solution is made of acid or alkali, if the removal of ash is excessive, there will be phenomenon that the ash removal liquid will corrode the plate surface, destroy the normal structure of the sand, make the sand mesh become flat and unfavorable to the plate material. Normal use. Therefore, the control of the density of the plate base is very important. The specific method of determining the density of the substrate by using a reflection densitometer is to randomly take the test plate strip, take three test pieces from the left, middle, and right parts of the plate more than 10 cm apart, cut into 10 cm×10 cm, and remove the photosensitive layer with acetone. , dry, cool to room temperature. First, the reflection density meter is adjusted to the white light level, and then the instrument is calibrated with the standard white plate. After reading the correction value, the reflection density value of each test piece is measured. The difference between the two values ​​is the base of the plate. Absolute density.
For example, if the correction value is 0.07 and the measurement value is 0.30, the absolute density is 0.23. Under normal circumstances, the base density is controlled between 0.19-0.25, indicating that the degree of ash removal is relatively normal. The determination method of the measurement contrast of the printing contrast is: taking a test piece, taking the exposure time required for the continuous graying of the third grade sun drying, and then measuring the unexposed portion and the exposed portion with a reflection densitometer The reflection density value of the two density values ​​is the print contrast of the test piece. The positive difference indicates that the trial version is the light-reducing type PS version, and the print contrast is more appropriate than -0.10. The achromatic type PS version has a print contrast of 0.10-0.20, and satisfactory results can be achieved. .
Determination of the contrast of the contrast The measurement method of the contrast of the contrast is: take the test piece and print it with the exposure time required for the continuous drying of the third step of the grading scale, and perform the normal development operation with the matching developer. (25°C± (1°C, time 30 seconds) After drying, the reflection density values ​​of the unexposed portion (solid bottom portion of the layout pattern) and the blank portion of the plate after exposure development were measured with a reflection densitometer. The difference between the two density values ​​was the value of the test piece. Development contrast. Usually the color is normal, that is, the dye is added to a plate made of a suitable photosensitive adhesive, and the development contrast value is between 0.50-0.65. The determination method of the substrate color of the plate base is determined by taking the test piece, performing normal exposure, developing, rinsing with clean water, and drying, removing the background color of the half-size test piece with acetone, and measuring the unremoved bottom with a reflection densitometer. The reflection density of the color part and the removal part of the background color, and the difference in the two density values ​​is the plate base color of the test piece. According to national industry standards, the base color of the plate should be less than 0.033.
The determination method of the base ash of the plate base ash is as follows: take the test piece, remove the plate photosensitive layer with acetone, then wipe off part of the layout with acid or alkaline removing agent or special ash remover, and leave it for 60 seconds. drying. The reflection densitometer was used to measure the reflection density values ​​of the uncoated erasure agent part and the wiping agent part, and the difference was the bottom ash value of the plate. According to our experience, bottom ash control is appropriate below 0.02. It is particularly emphasized that the bottom ash and the plate base color have obvious differences in terms of concepts and measurement methods, and should not be confused and should be taken seriously.
PS version of the photosensitive characteristics of the production of a specific production method is as follows: Take a uniform coating PS plate, with a continuous gray ash ladder for normal exposure, development, drying, with a reflective density meter continuous ash grading The density value of each level is then made into a curve.
For example, if the correction value is 0.07 and the measurement value is 0.30, the absolute density is 0.23. Under normal circumstances, the base density is controlled between 0.19-0.25, indicating that the degree of ash removal is relatively normal. The determination method of the measurement contrast of the printing contrast is: taking a test piece, taking the exposure time required for the continuous graying of the third grade sun drying, and then measuring the unexposed portion and the exposed portion with a reflection densitometer The reflection density value of the two density values ​​is the print contrast of the test piece. The positive difference indicates that the trial version is the light-reducing type PS version, and the print contrast is more appropriate than -0.10. The achromatic type PS version has a print contrast of 0.10-0.20, and satisfactory results can be achieved. .
Determination of the contrast of the contrast The measurement method of the contrast of the contrast is: take the test piece and print it with the exposure time required for the continuous drying of the third step of the grading scale, and perform the normal development operation with the matching developer. (25°C± (1°C, time 30 seconds) After drying, the reflection density values ​​of the unexposed portion (solid bottom portion of the layout pattern) and the blank portion of the plate after exposure development were measured with a reflection densitometer. The difference between the two density values ​​was the value of the test piece. Development contrast. Usually the color is normal, that is, the dye is added to a plate made of a suitable photosensitive adhesive, and the development contrast value is between 0.50-0.65. The determination method of the substrate color of the plate base is determined by taking the test piece, performing normal exposure, developing, rinsing with clean water, and drying, removing the background color of the half-size test piece with acetone, and measuring the unremoved bottom with a reflection densitometer. The reflection density of the color part and the removal part of the background color, and the difference in the two density values ​​is the plate base color of the test piece. According to national industry standards, the base color of the plate should be less than 0.033.
The determination method of the base ash of the plate base ash is as follows: take the test piece, remove the plate photosensitive layer with acetone, then wipe off part of the layout with acid or alkaline removing agent or special ash remover, and leave it for 60 seconds. drying. The reflection densitometer was used to measure the reflection density values ​​of the uncoated erasure agent part and the wiping agent part, and the difference was the bottom ash value of the plate. According to our experience, bottom ash control is appropriate below 0.02. It is particularly emphasized that the bottom ash and the plate base color have obvious differences in terms of concepts and measurement methods, and should not be confused and should be taken seriously.
PS version of the photosensitive characteristics of the production of a specific production method is as follows: Take a uniform coating PS plate, with a continuous gray ash ladder for normal exposure, development, drying, with a reflective density meter continuous ash grading The density value of each level is then made into a curve.
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