Re-polishing and cleaning standards

[Nick Bulloss]

I have a few standard blocks (mineral and pure elements) that need to be re-polished, cleaned and carbon coated. What polishing and cleaning methods have worked best for people? I had a suggestion of 1um diamond suspension for polishing (Peter McSwiggen). How do you best clean samples/standards without leaving any residue?
Thanks,
Nick

[Dan MacDonald]

Hi Nick:

I have tried a 0.25 micron aluminum oxide suspension on a fine silk lap and had fairly good results, after which I ultra-sonicate the standard block for several minutes and finish with a light rinse with methanol.  This method seems to work well with silicate mounts, but it isn't necessarily the best method for metal standards (especially Ti and Mg).  I am running into the same issues as you are with metal standards (e.g., the JEOL metals block), having tried methanol or ethanol as a suspension and rinsing agent.  Using an organic that is too reactive towards epoxy-based mounts can be disastrous, so it is best to try some of the solvent on the back side of the standard block first, to see if the solvent softens the epoxy at all.  One method I am toying with is using a dry-polish method using fine lapping films from Lee Valley - they have 0.5 and 0.1 um diamond lapping film http://www.leevalley.com/en/wood/page.aspx?p=68943&cat=1,43072 .  I think this would work well, and I am going to give it a try with a standard mount that I don't use anymore.  I use this type of film to polish my hand-carving tools at home.  I hope this helps.

Best regards

Dan MacDonald (Dalhousie University, Halifax, N.S., Canada)