In the production process of wooden doors, due to differences in raw materials, processing methods, paint painting, installation positions, etc., color difference will occur visually. In order to ensure that the color difference of wooden doors is within a reasonable range, wooden door manufacturers need to detect the color difference of wooden doors. So, is the color difference of wooden doors a quality problem? How to solve the color difference of wooden doors?
Reasons for color difference of wooden doors:
① Wood doors are made of different materials
Some are made of tree roots, and some are made of tree tops. The color near the roots is dark, and the color near the tops is light. The solid wood door is light in color and light in weight near the bark; The place near the center of the tree is dark and heavy.
② Each tree grows differently
The growth environment of each tree is different, the structure of the wood itself will also be different, and it will also have different colors and veins.
③ Different processing methods
Different factories have different ways of making doors. Wood doors have different methods of opening. Some are made by radial cutting, and some are made by chord cutting. After processing, the texture of the wood doors is not consistent. The two wood doors with different wood grain must have color difference visually.
④ Different painting processes
When the wood is spliced together, painting will also cause slight color difference due to the degree of wood absorption. The paint of each product should also be re mixed, and the color will also be slightly different due to different paint layers.
⑤ Different positions for installing wooden doors
Generally, the color of the wooden door close to the window is obviously brighter than that of the wooden door in the dark position, which is mainly affected by the sunlight.
Color difference of wooden door detected by color difference meter:
The traditional color difference evaluation method of wooden doors relies on the subjective visual evaluation of observers. Because of the difference in color perception ability of different observers, the color difference evaluation results of the same wooden door will be biased. In order to evaluate the color difference of wooden doors more objectively and accurately, a color difference meter can be used.
The colorimeter is a special testing instrument for measuring the color deviation. It can automatically compare the color difference between the sample plate and the tested object, and express the color difference by numerical value. When the colorimeter detects the color of an object, it simulates the process of human eyes looking at the color. The human eye has color perception of three basic colors: red, green, and blue. When making the photoelectric colorimeter, a light receiver that can sense the three colors of red, green, and blue is used to amplify the photocurrent that is sensed by each of them to obtain the stimulus amount of each color, so as to obtain this color signal. The chromaticity coordinate and luminance factor can be obtained by measuring the sample plate with the colorimeter. The position of the measured color in the chromaticity diagram can be known through the chromaticity diagram. In order to make the color space more consistent with the color difference of visual observation, x, y and Y are changed into a *, b * and L * values through a series of transformations. The size of a * value represents the red green phase (positive value is red), the b * value represents the yellow blue phase (positive value is yellow), and the L * value represents the brightness, that is, the black white phase (0 is black, 100 is white). In this way, each color shows a set of corresponding a *, b * L * values, and two different colors show different a *, b *, L * values Δ a、 Δ b、 Δ 50. The total color difference between chromaticity and lightness can be calculated to Δ E Table. The colorimeter can print a *, b * and L * data of two colors and directly print them through the computer system Δ E value, namely color difference. The user uses the color difference meter to measure the wooden door sample and standard sample respectively, calculate the excellent difference, and then quickly evaluate whether the color difference of the wooden door is within a reasonable range, so as to effectively control the color quality of the wooden door. The specific steps are as follows:
1. Sample preparation
Before the test, it is necessary to prepare a suitable sample. If the sample surface has obvious scratches, stains, etc., the accuracy of the measurement results will be affected. During the test, as the measuring hole of the colorimeter will contact the sample for many times, the surface of the untreated sample will be contaminated with the measuring diameter of the colorimeter.
2. Startup calibration
After the instrument is powered on, calibrate the instrument as required. After the instrument is calibrated successfully, it will enter the measurement interface. High precision colorimeter products generally have automatic correction function. Only the calibrated colorimeter can be used for measurement. If it is not calibrated, the test result is likely to have a large deviation.
3. Start measuring
Mark the prepared test sample, for example, A is the standard sample, B is the tested sample, and then start to measure the color difference between them. Place the sample at the measuring port of the instrument, and remember to block the measuring port to make it light tight. Press the measuring building on the side to measure.
4. Comparative analysis of results
The color difference value between the two samples is measured, and then compared with the color difference standard for analysis. The production process is adjusted according to the results, so as to control the color difference range.
Is the color difference of wooden doors a quality problem?
At present, neither the national standards nor the enterprise production standards have taken the color difference as the standard for testing quality, and the state has no clear provisions on the "color difference" of solid wood doors. They all follow the industry practice. Generally, if the design and style of the goods you buy are the same as the samples in the exhibition hall, and the color fluctuates within a small range in a color system, it belongs to normal color difference.
Generally speaking, the color difference of wooden doors is unavoidable. Wood is a porous material. Different parts have different material densities, and different parts absorb light and paint at different levels. Therefore, sometimes the colors on both sides of the same wooden door will appear different shades and textures.
There is no need to excessively pursue the non chromatic aberration of wooden doors. It is normal for wooden doors to have a slight color difference. The color difference value of wooden doors is within the allowable range. Generally speaking, it is reasonable not to exceed 5%.
It is the existence of color difference that highlights the uniqueness of each solid wood door. When choosing wooden doors, it is the key not to focus on quality and technology, is it?
