Once you have cast your sample, standards, and labels in an epoxy mount, it is time to lap and polish the surface. Again, the objective here is to obtain an analytical surface with no more than a few microns of relief – and negative relief is much better than positive relief. For samples that are much harder/softer than the epoxy, you will need to strike a balance between eliminating small scratches and creating surface relief by overpolishing (resulting in the softer material being removed faster).

There are a number of ways to polish an epoxy round and we can't offer detailed advice on each. Below, courtesy of specialist Brian Hess, we outline the general method developed at UW, which uses a progression of diamond grits (both fixed and loose) on a spinning polishing wheel. No matter which method you choose to use, we strongly urge you to practice your approach before polishing the mount(s) you will analyze at WiscSIMS. Polishing is a destructive process and it is possible to polish right though your sample and/or standard grains!

Important Note: Our recipe does not gurantee success, and does not impart the requisite skills or decades of experience required to master this process.

There are some third-party companies that will polish your sample for a fee, but we do not have extensive experience with any of them. You will want to carefully describe and document the degree of polishing you desire, and be sure to communicate the scientific value of each mount. If samples show polishing relief, it may be possible to fix with a diamond lapping film.

Third-party polishing services; please contact us for an up-to-date recommendation:

Materials used for lapping and polishing at UW:

And if you have access to a Buehler VibraMet system:

Step-by-step instructions:

Next step:

– Confirm sample flatness

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