Cross Hatch Cutter with Tape Water Testing Paint 100 grid disbonding

Water-based paint films have higher toughness and are less likely to peel off compared to oil-based paints. Most of these are cracked edges or localized warping. Daily quality checks rely on scratching and tape removal to determine adhesion. Even slight differences in technique can result in different final grading. For stable results and comparison, the entire process of cutting, chip removal, gluing, and tearing must be standardized.

Preparation for prototypes cannot be neglected in the early stages. The paint film must be thoroughly cured. Water-based paint has a long evaporation cycle for moisture and film-forming additives. If a hundred-grid test is done immediately after surface drying, the paint film will become soft, resulting in significantly lower test results and no indication of the finished product's adhesion. Select flat areas of the board surface for inspection, avoiding defects such as bubbles, shrinkage cavities, sagging, and oil accumulation. Defects have weak bonding strength and may detach prematurely, interfering with judgment. Wipe the surface in advance to remove dust and impurities, leaving no oil stains. Oil stains will cause the tape to be weak and weak to peel, resulting in an overrated grade.

Select the spacing of the slot blades according to the thickness of the dry film. 1mm blades are mostly used for applying thin water-based topcoats within 60μm, while 2mm blades are commonly used for thick anti-corrosion coatings. The condition of the blade determines cutting quality; if the blade shows curls, notches, or passivation, it must be replaced immediately. A blunt blade only squeezes and pulls the paint film, unable to cut through the coating directly to the substrate. The grid looks neat but is actually just a surface scratch. After pulling, the tape is hard to peel off and can easily be misjudged for adhesion to meet standards.

The cutting technique should be smooth and even. The two sets of lines for horizontal and vertical cuts are perpendicular to each other, with the same number of horizontal and vertical lines, forming a neat square grid. Apply even and stable hand pressure throughout, cutting through the paint film in one go and contacting the substrate. Do not repeatedly see back and forth, as repeated cutting will loosen the paint film at the grid edges, and the strip will peel off a large area later. Don't move too fast, as slipping blades can cause crooked lines and uneven grid sizes. After cutting, gently sweep off paint shavings along the diagonal with a soft brush, only scraping debris without rubbing back and forth to prevent loosening of the paint film prematurely.

Tape sticking and tearing are the most error-prone steps. Use industry-standard test tape, flatly and tightly adhere to the grid area, repeatedly press and roll with your finger to thoroughly remove air bubbles underneath the tape, ensuring a complete fit between the tape and grid. Any local slack can cause uneven tension. After leaving it for a few seconds, gently and quickly tear upward along the board at about a 60° angle. Avoid slow or repeated pulling. Water-based paint films have good ductility, and slow peeling makes it difficult to open up the hidden interfaces, resulting in noticeably high adhesion and loss of reference value.

After tearing, carefully check the peeling condition. Pay special attention to the edges of the grid and the cross-section, distinguishing three situations: only minor corner detachment, partial detachment of entire squares, and large-scale contiguous peeling. At the same time, distinguish the type of damage: tearing the paint film itself is considered cohesive damage, while separation between the film and substrate is considered adhesion failure. For one sample, select 2~3 different points for testing, and determine the grade based on multiple results. Don't draw conclusions based on just one point.

Usually, test data fluctuates greatly, mostly due to poor control of details. Common issues include blades not being replaced for a long time, cutting without cutting through the paint film, bubbles left when tape is adhered, uneven tear-pull angles and speeds, and insufficient paint film maintenance. Fengge is a qualitative rapid screening method; to accurately quantify adhesion, it can be verified together with pull tests.

Many people mistakenly think that drawing a grid means the test is complete. Water-based paint is especially sensitive to operational details, and even subtle differences in force can cause grading results to differ by one to two grades. Standardize blade specifications, cutting force, and tearing techniques to ensure stable results for parallel samples.

In summary, by standardizing the entire process of marking, chip removal, pasting, and peeling, you can stably complete the adhesion test of water-based paint with 100 grids. Controlling sample curing, tool conditions, and operating techniques reduces human error, facilitates comparison of adhesion differences caused by pretreatment, formulations, and construction methods of different substrates, and helps prevent peeling and peeling issues in the later stages.