Dyeing factories use light boxes for color matching. Why do observers have to color matching at 45 degrees?
Apr 17, 2021

Color matching light box can make samples, production, quality inspection and acceptance under the same standard light source, and accurately calibrate the color deviation of goods. It can be used for visual evaluation of color fastness of materials in textile, printing and dyeing industries, color matching proofing, discrimination of chromatic aberration and fluorescent substances, etc., to ensure that the color quality of goods meets the requirements, thus improving product quality and market competitiveness.

Color matching light box is usually a combination of various light sources, such as D65, D75 and D50 which can provide simulated sunlight, TL84, CWF and U30 which can simulate the lights in the exhibition hall of the store, and f and INCA which can be used as household lights, HORIZON of horizontal sunlight, UV lamp tube, etc. These light sources must be recognized by large international organizations, such as store lights recognized by Wal-Mart and Martha, daylight recognized by international testing organizations, and lights with various special requirements specified by customers, etc. There are many problems in using the standard light source box, some of which cause the color matching of the light box not to meet the standard because of some details, which has a bad influence on the subsequent production. Here are seven key steps to use the standard light source box. If you encounter similar problems, please refer to them.

1 standard use:

Key step one: observe the angle According to international standards, only two observation angles can be used, they are: A, zero-degree light source, 45-degree observation (0-45), that is, the light source shines on the sample from zero-degree (vertical) incident angle, and the observer observes the sample from 45 degrees. B, light source, 45 inclined table, 45 light source, observation at zero degree (0-45). In this layout, a special 45 °Fixed angle table should be used to make the light source irradiate the sample from 45 degrees, and the observer should observe the sample from zero degree (vertical).

Key step 2: 45 light source detects the placement position of the sample No matter using any of the above observation methods, it must be noted that the test samples should be placed in the middle of the light box as much as possible to reduce the influence of external light sources. In addition, the most important thing is that when the colors of two or more objects need to be compared, they should not be overlapped for observation as much as possible, and it is best to place them side by side for comparison.

Key step three: environmental factors in color matching All external light that will have the opportunity to irradiate the test sample must be avoided as far as possible. If the window is in the visual field, it should also be covered with gray curtains, so it is most ideal to use the color light box in the dark room. Another point is often overlooked, that is, no other sundries should be placed in the color light box.

Key step 4: Requirements for converting light sources According to our daily life experience, in our eyes, it is like having a register. When the color changes in a very short time, we can feel it clearly. Therefore, when observing metamerism, if you want to change the light source, you must do it in an instant, and don't light up after blinking like the lighting tubes we use every day, which will irritate the eyes and affect the evaluation results.

Key step 5: Have the function of testing metamerism effect The so-called metamerism effect means that under a certain light source, the color displayed by the sample is the same as required, but under another light source, the color difference cannot be accepted. For example, under D65 light source, the color is no different from the standard, but under A light source, the sample color is unacceptable. Therefore, all equipment for color light sources must be equipped with two or more light sources to test the metamerism effect.

Key step 6: arrangement position of lamp tubes Although there is no specific requirement for the arrangement position of the lamps, their distribution position must have a uniform light source in the color light box, and must never be tilted to a certain area. , and manufacturers will also specify that the quality of their products will remain within acceptable tolerances during a certain period of operation. Therefore, an accurate time recorder is indispensable. Usually, these lamps need to be replaced if they are used for more than 2000 hours or one year.

2 routine maintenance:

1. The selection of various light sources in the color light box is controlled by the touch buttons corresponding to the names of light sources on the box body, so as to realize quick switching and quick lighting. The two objects with color deviation to be compared are placed in the central symmetrical position of the color light box, and the best observation angle is provided that the angle between the human eye or light and the object to be measured is 45 degrees.

2. When using the light box, try to avoid external light irradiation on the detected objects, and at the same time, no other sundries shall be placed in the light box.

3. After the lamp tube of the color light box is used for more than 2000 hours, a new lamp tube should be replaced to avoid the effect of visual observation of color due to the aging of the lamp tube.

4. If the inner wall plate of the light box is stained with stains, it can be wiped clean with a clean soft cloth dipped in a low-concentration alkaline cleaner to make the inner frame clean and dry, so as to avoid damage to the light-absorbing coating on the inner wall of the light box by the detected articles and affect the color matching effect.

5. If the inner plate of the light box is damaged and cannot absorb light, it should be replaced again. New lamps should be replaced when both ends of lamps are blackened and aged due to overtime use.

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