Cross-Cut Adhesion Test Kit
The Cross-Cut Kit by Precision Gage & Tool Company provides almost everything you need to perform adhesion and flexibility tests to meet the standards of the ASTM test method D-3359. Each kit includes a blade, a blade holder/handle, a hex wrench for changing blades, an extra clamp screw, a small flaking and cleaning brush, a lighted magnifier and a roll of test tape. Each cross-cut adhesion kit comes in a finished wooden case with instructions.
Testing Materials and Procedure
The information below is taken from the included cross cut adhesion test kit instructions and is also available for download here.
The Cross-Cut Kit by Precision Gage & Tool Company provides almost everything you need to perform Adhesion and Flexibility Tests to meet the standards of ASTM Test method D-3359. In the kit, you’ll find a blade, a blade holder/handle, a hex wrench for changing blades, an extra clamp screw, a small flaking and cleaning brush, a lighted magnifier, and a roll of test tape. You’ll also need a rubber eraser on the end of a pencil.
In the field, you’ll test the actual coated structure or article you want to evaluate. In the lab, you may apply the materials you’re testing to panels of the appropriate composition and surface conditions. Either way, the testing surface must be flat. You can check flatness with a straight edge such as a steel rule.
- Make sure your specimen is at room temperature (or other mutually agreed upon temperature) and placed on a firm base.
- Select an area free of blemishes and minor surface imperfections. Under the illumination of the magnifier, use the cross-cut tool tomake parallel cuts as follows:
- For dry film coatings of thickness of 2.0 mils (50 μm) or less, use a fine blade (1.0 mm spacing). For coatings having a dry film thickness between 2.0 mils (50 μm) and 5 mils (125 μm), choose a medium (1.5 mm spacing) or coarse (2.0 mm spacing) blade.
- Make the first cut about 3/4 in. (20 mm) long. Cut through the film to the substrate in one steady motion, using just enough pressure to reach the substrate.
- After making the cut, gently remove any detached flakes or ribbons from the film with your kit’s brush.
- Next, make a second cut at 900 to and centered on the original cuts to create a grid pattern in the film.
- Brush the area again and inspect the cuts to make sure you’ve reached the substrate. If not, make another grid in a different location.
- Remove two complete laps of your kit’s test tape and discard. Remove an additional length at a steady rate (don’t jerk it) and cut a piece about 3 in. (75 mm) long.
- Place the center of the tape over the grid and smooth it into place. To make good contact with the film, rub the tape firmly with a pencil eraser. The color under the tape helps you determine when you’ve made good contact.
- Wait about 90 seconds, then remove the tape. Seize the free end and quickly (without jerking) pull it back upon itself as close as possible to a 1800 angle.
- Using the kit’s illuminated magnifier, inspect the grid area for coating removal. Rate the coating’s adhesion according to the test results classification chart below;
click image to enlarge
Report the number of tests, their mean and range, and where the failure occurred—i.e., between the first coat and substrate, between the first and second coat, etc. Note the substrate used, the type of coating and the method of cure. If the adhesion strength of the tape has been determined in accordance with Test Methods D 10001 or D 33302, report the results with the adhesion ratings. Otherwise, report the specific tape used.
Precision and Bias
Use the following criteria to judge the acceptability of your results.
Repeatability — If adhesion is uniform over the surface being tested, results obtained for two measurements by the same operator should not differ by more than one rating category.
Reproducibility — Test results obtained by different operators (each the mean of two measurements) should not differ by more than two rating categories.
Bias cannot be established for these test methods.