Do you have a micrometer or calipers?
What follows I have posted before. Have found that if you can find one, a radius anvil micrometer works even better than a standard micrometer for compressed measurements of patch material. As an example, with normal pressure on a regular micrometer, a piece of denim may measure about .022” thick, however, this is NOT the important measurement. What is important, at least in my opinion and experience, is the compressed thickness. In this case, about .0155”. Also very important is how consistent you measure that thickness. I use a micrometer with a radius anvil and apply normal torque pressure as I measure. The radius anvil allows for a small area to be easily compressed. A standard flat anvil micrometer works also, you just have to be a bit more careful with how you apply pressure to compress the fabric to get consistent readings, at least in my opinion. Hope the following photographs help explain.
Below are two more photographs showing measurements of a different lot of denim. Normal measurement is .018” thick. Compressed, .0085” thick. With .012” deep grooves would expect it to fail spectacularly as a patch material.
