The Secret to Flawless Silk Screen Printing on Cosmetic & Glass Bottles

At a time when competition in the cosmetics industry is becoming increasingly fierce, the silk screen quality of cosmetic bottles, Glasflaschen and other packaging materials has become an important manifestation of brand image. This article focuses on silk screen product testing, deeply analyzes the silk screen testing environment, common defects and reliability testing methods, and provides industry practitioners with a set of systematic and practical silk screen product quality control solutions through detailed data, tables and illustrations, helping companies to ensure product quality and enhance market competitiveness under short delivery requirements.

1. Silk screen testing environment: Accurately control the basic conditions of testing

The testing environment of silk screen parts has a vital impact on the accuracy of the test results. In terms of light intensity, the test needs to be carried out under the lighting conditions of 200-300LX, which is equivalent to the light intensity of a 40W fluorescent lamp at a distance of 750MM. Under this lighting condition, the inspector can observe the subtle defects on the surface of the silk screen more clearly.

The product placement angle is also critical. The product inspection surface should be approximately 45° to the inspector’s visual direction (as shown in Figure 1), and the observation time should be maintained for about 10 seconds. This angle setting can make the light form a suitable reflection on the product surface, making it easier for inspectors to find various defects. At the same time, according to the different levels of the product surface, the distance between the inspector’s visual direction and the surface of the product to be inspected is also different: Class A surface (external surface that can be directly viewed) is 400MM; Class B surface (unobvious external surface) is 500MM; Class C surface (internal and external surfaces that are not easy to see) is 800MM. This hierarchical setting ensures accurate inspection of different parts.

2. Common defects of screen printing: clearly identify quality risks

In the process of screen printing of cosmetic bottles and glass bottles, there are many common defects, which will directly affect the appearance and performance of the product.

Foreign matter: After screen printing, dust, dots or filaments are easily attached to the surface of the coating. These foreign matters not only affect the aesthetics of the product, but may also cause a bad experience for consumers during subsequent use.

Base exposure: The base color is exposed because the ink at the screen printing position is too thin. This situation is particularly obvious in the screen printing of cosmetic packaging materials with high requirements for color consistency, which will seriously affect the overall visual effect of the product.

Misprinting: The position where the screen printing is required is not screen printed, which directly leads to missing product information or incomplete patterns, and cannot meet the brand logo and design requirements.

Blurred / Broken Line: Poor screen printing process makes the screen printing lines and patterns uneven in thickness, blurred, and the word lines are partially disconnected. This defect will reduce the recognition of the product and affect the communication of the brand image.

Uneven screen printing thickness: Due to improper screen printing operation, the screen printing layer of dots, lines or patterns has thickness differences. This not only affects the appearance of the product, but may also cause inconsistent ink adhesion and reduce product durability.

Misalignment: The screen printing position is inaccurate and offset occurs. For cosmetic glass bottles with strict design requirements, misalignment will destroy the coordination and beauty of the overall pattern.

Poor adhesion: The adhesion of the silk screen coating is insufficient, and the silk screen part can be pasted off with 3M adhesive tape. This means that the silk screen content is easy to fall off during transportation or use of the product, affecting the product quality.

Pinhole: The surface of the coating presents pinhole-like small holes, which not only affects the appearance, but also may affect the protective performance of the ink.

Abrasions/scratches: After the silk screen is completed, the surface is scratched or scratched due to poor protection, which reduces the quality grade of the product.

Color/stains: Non-silk screen colors adhere to the silk screen surface, destroying the color uniformity of the product and affecting the visual effect.

Color difference: Compared with the standard color plate, the silk screen color has deviations. In the cosmetics industry, color accuracy is crucial to the brand image, and color difference may cause consumers to question the product.

3. Silk screen reliability test method: comprehensive verification of product quality

In order to ensure the quality stability of cosmetic glass bottle silk screen products in various environments and usage scenarios, a series of reliability tests are required.

High temperature storage test

The storage temperature is set to + 66°C and the storage time is 48 hours. The sample is placed at room temperature for 2 hours after it comes out of the oven. The printed surface must not have wrinkles, blistering, cracks, or peeling, and the color gloss must not change significantly. This test simulates the storage of the product in a high temperature environment and verifies the stability of silk screen under high temperature conditions.

Low temperature test

The storage temperature is – 40°C and the storage time is 48 hours. Similarly, the sample is placed at room temperature for 2 hours after it comes out of the oven. The printed surface must not have wrinkles, blistering, cracks, or peeling, and the color gloss must not change significantly. This test is used to test the tolerance of silk screen in a low temperature environment.

High temperature and high humidity storage test

The storage temperature/humidity is + 66°C/85%, and the storage time is 96 hours. After the test, place it at room temperature for 2 hours to check if there is no wrinkling, blistering, cracking, or peeling on the printed surface, and there is no obvious change in color and gloss. This test simulates a harsh environment of high temperature and high humidity to evaluate the moisture and deformation resistance of silk screen printing.

Thermal shock test

The storage temperature is cycled between – 40°C and + 66°C, -40°C~+66°C is one cycle, and the temperature conversion time does not exceed 5 minutes, for a total of 12 cycles. After the sample is taken out of the oven, place it at room temperature for 2 hours. The parts and printed surface should not have wrinkles, blistering, cracking, or peeling, and there should be no obvious change in color and gloss. The thermal shock test tests the adaptability of silk screen printing in an environment with rapid temperature changes.

Silk screen / pad printing adhesion test

The purpose of the test is to evaluate the adhesion of silk screen / pad printing paint. Use 1.3M600 transparent tape or transparent tape with a stickiness greater than 5.3N/18mm, stick the tape on the printed font or pattern of the sample, flatten it with your hands, pull up the tail of the tape at 90 degrees to the test surface, quickly tear off the tape, and repeat the same part 3 times. The acceptance standard is to observe the surface with the naked eye, and the silk/pad printing font or pattern is clearly discernible without peeling.

Friction test

The purpose is to evaluate the adhesion of paint and silk/pad printing paint on the coating surface. The test equipment is an eraser. Fix the specimen, rub it back and forth with a vertical force of 500G and a stroke of 15MM. Each single stroke is one time, and the silk/pad printing font or pattern is rubbed continuously for 50 times. Observe the surface with the naked eye. The wear cannot be seen to the bottom, and the silk/pad printing should be clear and discernible to be qualified.

Solvent resistance test

Isopropyl alcohol test: Take 1ml of isopropyl alcohol solution and drop it on the sprayed surface or silk/pad printing surface of the sample. After 10 minutes, wipe the isopropyl alcohol solution with a white cloth.

Alcohol resistance test: Soak a cotton ball or white cloth in a 99% alcohol solution, and wipe back and forth 20 times at the same position of the sample printed font and pattern at a pressure of 1kg and a speed of 1 round trip per second. After wiping, the printed font or pattern on the surface of the sample should be clearly visible, and the color should not lose gloss or fade to be qualified.

Thumb test

The experimental sample needs to be more than 5PCS. Take the sample and place the thumb on the printed picture, and rub it back and forth 15 times with a force of 3+0.5/-0KGF. The printed pattern of the product cannot have gaps, broken lines, and poor ink adhesion, otherwise it will be unqualified.

75% alcohol test

Conditions include more than 5 PCS of experimental samples, white cotton gauze, 75% alcohol, and 1.5+0.5/-0KGF fixture. Tie white cotton gauze to the bottom of the 1.5KG fixture, dip it in 75% alcohol, and move it back and forth 30 times (about 15SEC) on the printed pattern. The printed pattern of the product must not fall off, have gaps and broken lines, or have poor ink adhesion. Light colors are allowed, but the printed pattern should be clear and not blurred, otherwise it is unqualified.

95% alcohol test

Similar to the 75% alcohol test process, 95% alcohol is used, and the experimental judgment criteria are the same to ensure the tolerance of silk screen printing in different concentrations of alcohol environments.

810 tape test

For more than 5 PCS of test samples, completely stick the 810 tape on the silk screen, then quickly pull up the tape at a 45-degree angle and measure three times in a row. The printed pattern of the product shall not be nicked or broken.

3M600 tape test

For more than 5 PCS of experimental samples, completely stick the 3M600 tape to the screen printing, and quickly pull up the tape at a 45-degree angle. Only one test is required. The printed pattern of the product shall not be nicked or broken.

250 tape test

For more than 5 PCS of experimental samples, completely stick the 250 tape to the screen printing, and quickly pull up the tape at a 45-degree angle for three consecutive times. The printed pattern of the product shall not be nicked or broken.

Gasoline wiping test

The conditions are more than 5 PCS of experimental samples, white cotton gauze, gasoline mixture (gasoline: 75% alcohol = 1:1), and 1.5+0.5/-0KGF tool. Tie white cotton gauze to the bottom of the 1.5KGF fixture, dip it in gasoline mixture, and go back and forth 30 times (about 15SEC) on the printed pattern. The printed pattern of the product must not fall off, have gaps, broken lines, poor ink adhesion, etc. The color can be light, but the printed pattern should be clear and not blurred, otherwise it is unqualified.

N-hexane wiping test

For more than 5PCS of experimental samples, tie white cotton gauze to the bottom of the 1.5KGF fixture, dip it in n-hexane solution, and go back and forth 30 times (about 15SEC) on the printed pattern. The printed pattern of the product must not fall off, have gaps, broken lines, poor ink adhesion, etc. The color can be light, but the printed pattern should be clear and not blurred, otherwise it is unqualified.

Zusammenfassung

The inspection of cosmetic bottle glass bottle silk screen products is a key link to ensure product quality. From strict testing environment setting, to accurate identification of common defects, to comprehensive reliability testing methods, each step has an important impact on product quality. Through the testing scheme introduced in this article, companies can systematically control the quality of silk-screen products and ensure that the products meet the needs of brands and consumers in terms of appearance and durability. As the cosmetics industry continues to shorten the delivery period of packaging materials, paying attention to silk-screen product testing will help companies improve product competitiveness and establish a good brand image. In the actual production process, companies should reasonably use these testing methods according to their own product characteristics, and continuously optimize the testing process to adapt to market changes and customer needs.

Yafeng Packaging is committed to providing top – notch quality assurance. We have established a rigorous quality control system, especially for screen – printing quality testing. From the inspection environment to the most comprehensive reliability tests, every step is strictly implemented in accordance with international standards. Our professional technical team and advanced testing equipment ensure that each batch of products meets or exceeds customer expectations, making us your reliable partner for high – quality cosmetic packaging.