Etch with Kroll's after each 3µm, 1µm and 0.02µm Silica polishes. Can see grains using polarized light before etch

Hello

I would advise you to start with the emery paper of 600 till 2000 and do not use the 200, 300 and 400 ones.

You should follow this by metal polishing paste with rag wheel brush which is attached to a low speed dental motor to get a surface roughness of about 0.05 - 0.07 microns.

The emery paper especially the rough ones without the use of a polishing paste will cause surface scratches and high values of surface roughness.

There should not be a problem starting with 220-grit grinding. It might be necessary to reach the depth you want. It might also be necessary to remove the damage from the previous processing. But you need to consistently remove the previous step's damage as you work through the sequence. For example, if you still have damage from 400-grit when you move on from 600-grit, you will never remove those scratches at 800-grit and beyond.

For that reason, I do not continuously rotate the sample when polishing by hand. I will rotate the sample 90 degrees at changes of grit. I want to make sure that all the scratches are only from the current grit. I don't want to see any at an angle from the previous stage. I take as long as necessary to remove the previous damage. It may be only a minute, but the time will depend on the pressure and the material.

You only mentioned 3 um for polishing. That will not be fine enough. I use 1- um diamond for SEM work. Finer sizes will be needed for optical and EBSD. If you use silica, be sure to clean it away IMMEDIATELY! Do not let it dry on the surface. Chemical etching may help, but I don't like that for SEM. I don't normally want to preferentially remove material, and that is how etching works.

Be sure polishing substrates are clean. If they accumulate dust from the room or other contamination, that can leave significant scratches.