Whilst there are a variety of methods and equipment used to test the adhesion of a coating, one of the simplest techniques is cross hatch testing. The Elcometer 107 Cross Hatch Cutter is an ideal tool to carry out this technique as it provides instant assessments and can be used on a wide range of products thanks to its rugged construction.

It’s regularly used by both coating manufacturers and quality control professionals and has proven particularly effective when assessing coatings which need to withstand environmental factors, mechanical stress, or corrosion.

In this video, we will be demonstrating how you can undertake fast and accurate adhesion tests using a Cross Hatch Cutter.

So, how does it work?

A key point to note is that the Elcometer 107 can be used in accordance with both ISO/JIS and ASTM Standards. Depending on which Standard you are working towards, your test procedure will change slightly. 

For the purposes of this video, we will be demonstrating the procedure which conforms to ASTM requirements. If you work towards ISO/JIS, don’t worry – variances are minimal and full information on them can be seen in the product’s instruction manual.

To begin, you need to ensure that you are using the appropriate cutter blade. Your choice of blade will be informed by the substrate type as well as the test method being used; the table shown on screen provides more information on this.

As in this example, we are working towards ASTM standards, and using a substrate with a coating thickness of 100 microns, or 4mils, we will be using a 6x2mm cutter.

Once you have selected the blade which meets your test requirements, and fitted it using the hexagonal wrench supplied, you should then place the cutting edge on the sample.

Using a firm grip and a steady movement, pull the adhesion tester towards you to make a series of parallel cuts which stretch approximately 20mm in length.

Next, reposition the cutting the edge on the sample at a 90° angle to the first cut and, again, pull towards you, making another series of cuts so that a lattice pattern is created on the coating.

Remove any debris which remains on the pattern by brushing the sample lightly and, once clear, inspect the substrate to ensure that cuts have penetrated through the coating.

If you are satisfied that they have done so, you should centre a piece of tape, approximately 75mm in length, over the cuts. To ensure that the tape remains in place, rub along the surface firmly.

Within one to two minutes of the tape being applied, it should be peeled off in a single smooth action at an angle of 180 degrees to the surface.

At this point, you will be ready to assess the coating’s adhesion by viewing the lattice of cuts. For this, you’ll need your magnifier handy as well as a copy of the latest visual standards provided by your conforming body.

Both ISO/JIS and ASTM bodies evaluate adhesion quality based upon the amount of coating removed from the surface and the overall damage to the cross-hatch pattern. They agree that well-adhered coatings will largely remain intact whereas poorly adhered coatings will show significant flaking.

As you can see from the results, the appearance of our substrate indicates strong coating adherence as the edges of cuts are completely smooth and none of the lattice is detached. We can therefore record this as a 5B result in accordance with ASTM classifications and rest assured that the coating meets quality requirements.

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