Five main factors contributing to color difference in packaging bags have been identified.

Factor 1: Ink Procurement Stage

Did you follow the ink procurement procedure when selecting and purchasing ink? Normally, before selecting ink, we need to understand the ink system and the hue deviation of each color. For example, magenta leans towards blue, and yellow has variations in hue, including blueish hues. Therefore, when selecting ink, it must meet the company's product printing hue requirements. At the same time, we should also do a good job of archiving the original color ink samples for the first ink use, providing a basis for subsequent ink inspection and sampling. Generally, the use of ink goes through small sample, pilot test, medium-scale test, large-scale test, and mass production. Samples and printed samples should be saved each time to evaluate the hue stability of the ink supplier. This is the first step in avoiding color difference.

Factor 2: Sample Preservation Stage

Improper sample preservation leads to color differences in printed products. Currently, many printing companies do not pay attention to standardized sample management, and sample preservation is also not standardized. When printing is needed, samples are searched everywhere, sometimes samples cannot be found, and there are even situations where sales representatives obtain samples from customers. For such companies, color differences will be endless.

Factor 3: Sample Production Stage

So how to manage it? We are managed directly by the quality control department. Color samples are mainly divided into customer-signed samples and customer-provided samples. For the first printing of a new layout, in most cases, we have the customer directly confirm and sign the sample. The customer-signed sample should be properly kept and stored in the designated product file bag. However, we need to remind many printing companies that they do not pay attention to this issue, resulting in the inability to trace the customer-signed sample during subsequent normal production, causing unnecessary business communication and disputes.

So what work should we do when tracing customer-provided samples? Because customer samples are subject to plate making, ink, and printing technology, it may be difficult to completely replicate the color of the customer sample in normal color matching printing. Before plate making, we need to communicate with the customer about the color deviation and requirements. Then, the plate maker makes the plate according to the customer's hue requirements. This can effectively reduce color difference problems caused by sample tracing.

Factor 4: Sample Storage Stage

After all new and revised products are confirmed for printing, samples must be preserved immediately. Sample preservation requirements: printed products are clear and complete, without printing quality problems, with proper register, and the hue meets the signed and traced sample requirements. The sample length is 2 plate circumferences. Remarks: production time, production team, new or revised version, signature confirmation, and fill in the sample preservation notification form for posting.

When the finished film is laminated, samples are preserved according to the sample preservation notification form. Sample preservation requirements: no printing and lamination quality problems, no obvious scratches on the surface, and the sample handover confirmation form is completed.

After receiving the samples, the quality control department personnel will verify the samples and signatures. After verification, standard sample cutting is performed. The edges should retain the register color circles or color sequence blocks, and the complete vertical and horizontal dot patterns are cut. Then, the sample is pasted onto the designated sample paper. Note whether it is a new or revised version. The quality control department uniformly stamps the sample with a special stamp and attaches the signature of the person in charge of the quality control department. All workshops use the quality control department's sample as the standard. This ensures the consistency of sample management and execution. When the customer needs to change the color, pay attention to timely replacement and distribution to various production workshops for timely and consistent samples! In addition, when preserving samples, we should pay attention to the upper and lower limit samples, that is, the deviation range of the hue, so that printing and quality control personnel can better control the hue trend and color difference on site.

Factor 5: Printing Stage Factors

Plate rollers: After printing is completed, be sure to clean and maintain the plate rollers. This step must not be neglected. If the image area of the plate roller is not cleaned properly, it is easy to cause dot clogging, resulting in incomplete ink transfer, and color difference is inevitable. Why sometimes we cannot match the color to the sample, and why there are plate clogging problems during production, this is the reason. The cleaning standard of the plate roller should be that there is no ink on the head and roller body, and it should be clean and tidy. In addition, we can do some data on the printing durability of the plate roller, which can help with color difference. Currently, our normal plate roller printing durability is around 300,000 meters. From the first printing, we can record the printing meterage, which helps to judge in advance when the plate roller needs to be repaired, and helps to reduce the ink transfer rate due to shallow plate problems, thus causing color difference and inability to produce normally during color matching.