Testing methods for silk screen products

As brands demand shorter delivery times for packaging materials, the spot demand from suppliers highlights the importance of post-processing processes for cosmetic packaging materials, such as graphic and textual silk screen printing of plastic bottles, glass bottles, lipstick tubes, air cushion boxes, and other packaging materials.

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Testing environment for silk screen parts

1. Luminance: 200-300LX (equivalent to a 40W fluorescent lamp with a distance of 750MM)

2. The surface of the product needs to be inspected and the visual direction of the inspector is approximately 45 ° (as shown in the figure below), taking about 10 seconds

3. The distance between the inspector's visual direction and the surface of the product to be inspected is as follows:

Class A surface (external surface that can be directly viewed): 400MM

B-grade surface (inconspicuous external): 500MM

C-level surface (non visible internal and external surfaces): 800MM

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Common defects in silk screen printing parts

1. Foreign objects: After screen printing, the coating adheres to dust, dots, or filamentous foreign objects.

2. Exposed background: Due to the thin screen printing position, the background color is exposed.

3. Misprinting: It is required that the silk screen position is not reached.

4. Blurred/disconnected; Poor screen printing results in uneven thickness and blurriness of screen printing lines and patterns, as well as partially disconnected character lines.

5. Uneven thickness of silk screen: Due to improper silk screen operation, the thickness of the silk screen layer on dots, lines, or patterns is uneven.

6. Misalignment: Due to inaccurate screen printing position, the screen printing position is offset.

7. Poor adhesion: The adhesion of the silk screen coating is insufficient, and it can be removed with 3M adhesive paper.

8. Pinhole: The surface of the coating can see pinhole like small holes.

9. Scratches/scratches: caused by poor protection after screen printing

10. Miscellaneous colors/stains: Non silk screen colors adhere to the silk screen surface.

11. Color difference: There is a color deviation compared to the standard color palette.

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Testing method for reliability of silk screen printing

1. High temperature storage test

Storage temperature:+66 ° C

Storage time: 48 hours

Acceptance criteria: After the sample is produced and left at room temperature for 2 hours, the printed surface shall have no wrinkles, bubbles, cracks, peeling, and no significant changes in color or gloss

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2. Low temperature test

Storage temperature: -40 ° C

Storage time: 48 hours

Acceptance criteria: After the sample is produced and left at room temperature for 2 hours, the printed surface shall have no wrinkles, bubbles, cracks, peeling, and no significant changes in color or gloss

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3. High temperature and humidity storage test

Storage temperature/humidity: +66 ° C/85%

Storage time: 96 hours

Acceptance criteria: After the sample is produced and left at room temperature for 2 hours, the printed surface shall have no wrinkles, bubbles, cracks, peeling, and no significant changes in color or gloss

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4. Thermal shock test

Storage temperature: -40 ° C/+66 ° C

Cycle description: -40 ° C~+66 ° C is a cycle, and the transition time between temperatures does not exceed 5 minutes, totaling 12 cycles

Acceptance criteria: After the sample is produced and left at room temperature for 2 hours, check that the parts and printed surfaces are free of wrinkles, bubbles, cracks, peeling, and there is no significant change in color or gloss

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5. Silk/pad printing adhesion test

Test purpose: To evaluate the adhesion of silk/pad printing paint

Test tool: 3M616/600/810 tape or transparent tape with a adhesion force greater than 5.3N/18mm

Test method: Apply 3M616/600/810 tape to the printed font or pattern of the sample to be tested, press it flat with your hand, and then pull up the tail of the tape at a 90-degree angle to the test surface. Quickly remove the same part of the tape and repeat 3 times

Acceptance criteria: When observing the surface with the naked eye, the silk/pad printing font or pattern should be clear and distinguishable, without peeling

6. Friction test

Test purpose: To evaluate the adhesion of coated surface paint and silk/pad printing paint

Test equipment: eraser

Test method: Fix the test piece and rub it back and forth with a vertical force of 500G and a stroke of 15MM, with one stroke per stroke Silk/pad printing font or pattern, continuously rubbing 50 times

Acceptance criteria: Visually observe the surface, wear should not be visible, and silk/pad printing should be clear and distinguishable

7. Solvent resistance test

(1) Isopropanol test

Take 1ml of isopropanol solution and drop it onto the spray surface or silk/pad printing surface of the sample. After 10 minutes, dry the isopropanol solution with a white cloth

(2) Alcohol resistance test

Test method: Soak a 99% alcohol solution with a cotton ball or white cloth, and then rub back and forth 20 times at the same position as the printed font and pattern on the sample at a pressure of 1kg and a speed of 1 second

Acceptance criteria: After wiping the surface of the sample, the printed font or pattern should be clear and visible, and the color should not have any loss of luster, color fading, or other phenomena

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8. Thumb test

Conditions: More than 5PCS of experimental samples

Experimental procedure: Take a sample and place it on the printed image with your thumb. Rub it back and forth 15 times with a force of 3+0.5/-0KGF.

Experimental judgment: The printed pattern of the product should not be chipped, broken, or have poor ink adhesion, otherwise it is considered unqualified.

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9. 75% alcohol test

Conditions: Experimental samples of at least 5PCS, white cotton gauze, 75% alcohol, 1.5+0.5/-0KGF preparation

Experimental procedure: Tie the bottom of a 1.5KG fixture with white cotton gauze, dip it in 75% alcohol, and then use white cotton gauze to make 30 round-trips (approximately 15SEC) on the printed pattern

Experimental judgment: The printed pattern of the product should not have peeling, gaps, broken lines, or poor ink adhesion. Light color is allowed, but the printed pattern should be clear and not blurry, otherwise it is considered unqualified.

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10. 95% alcohol test

Conditions: Prepare at least 5PCS of experimental samples, white cotton gauze, 95% alcohol, 1.5+0.5/-0KGF

Experimental procedure: Tie the bottom of a 1.5KG fixture with white cotton gauze, dip it in 95% alcohol, and then use white cotton gauze to make 30 round-trips (about 15SEC) on the printed pattern

Experimental judgment: The printed pattern of the product should not have peeling, gaps, broken lines, or poor ink adhesion. Light color is allowed, but the printed pattern should be clear and not blurry, otherwise it is considered unqualified.

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11. 810 Tape Test

Conditions: Test samples of 5 pieces or more, 810 tape

Experimental procedure: Fully stick 810 tape onto screen printing, then quickly pull up the tape at a 45 degree angle and measure it three times in a row.

Experimental judgment: The printed pattern of the product should not be chipped/broken.

12. 3M616/600 tape testing

Conditions: More than 5PCS of experimental samples, 616/600 adhesive tapes

Experimental procedure: Fully adhere 3M616/600 tape to screen printing and quickly pull up the tape at a 45 degree angle. Just test once.

Experimental judgment: The printed pattern of the product should not be chipped/broken.

13. 250 tape test

Conditions: More than 5PCS of experimental samples, 250 adhesive tapes

Experimental procedure: Fully adhere 250 tape to screen printing, quickly pull up the tape at a 45 degree angle, and perform three consecutive tests.

Experimental judgment: The printed pattern of the product should not be chipped/broken.

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14. Gasoline wipe test

Conditions: Preparation of 5 or more experimental samples, white cotton gauze, gasoline mixture (gasoline: 75% alcohol=1:1), 1.5+0.5/-0KGF

Experimental procedure: Tie the bottom of a 1.5KGF fixture with white cotton gauze, dip it in gasoline mixture, and repeat 30 times on the printed pattern (about 15 SEC)

Experimental judgment: The printed pattern of the product should not have peeling, chipping, broken lines, poor ink adhesion, etc. The color may be slightly lighter, but the printed pattern should be clear and not blurry, otherwise it is considered unqualified.

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15. N-hexane wiping test

Conditions: Prepare at least 5PCS of experimental samples, white cotton gauze, n-hexane, 1.5+0.5/-0KGF

Experimental procedure: Tie the bottom of a 1.5KGF fixture with white cotton gauze, dip it in n-hexane solution, and repeat 30 times on the printed pattern (about 15 SEC)

Experimental judgment: The printed pattern of the product should not have peeling, chipping, broken lines, poor ink adhesion, etc. The color may be slightly lighter, but the printed pattern should be clear and not blurry, otherwise it is considered unqualified.