Met Tips: LECO's Metallography Troubleshooting Guide

Have you ever let long-cure epoxy mounts cure overnight, only for the setscrew to push into the mount when you went to load it into your grinder/polisher’s fixed specimen holder? When the epoxy is soft, the specimen isn’t secure in the mount or in the specimen holder, and proper grinding and polishing becomes impossible. The eight hour cure time for long cure epoxy means you can’t just whip up a new one; if something goes wrong, you’ve effectively lost an entire day as the replacement also needs eight hours to cure.

But if you left your mounts to cure overnight, shouldn’t that have been more than enough time? What could have gone wrong?

Cracks in your mount are never a welcome sight. While a scratched specimen doesn’t always have a cracked mount, a mount with radial cracks is far more likely to cause a future scratched specimen. While we covered the scratches in an earlier tip, we can’t ignore the cracks.

There is a certain sort of frustration that comes with putting a completed multi-step metallographic preparation beneath the microscope, taking a look, and seeing a discolored or stained surface. While a few types of stains can be ignored, many stains mean something went wrong during the preparation.