The last weeks of term are always a challenge in getting everything finished, but this term one task in particular – polishing SEM samples – took its toll on everybody’s patience.
The SEM (Scanning Electron Microscope) is a powerful analytical tool for our work. However, the sample preparation process is rather tedious. Just a quick reminder, a scanning electron microscope uses an electron beam (rather than light with standard optical microscopy) to produce images up to 500,000 x magnification.
Although there are several different methods for preparing these samples, our technique involved mounting our samples in resin (Clear Casting Resin POLYLITE 32032-00 from Alex Tiranti Ltd., to be specific), using ice-cube trays as moulds.
Once cast, the resin block has to be prepared and sawn into the correct shape. This often requires some elbow grease and several sacrificial saw blades. The sample is then polished to the smoothest possible surface. This required four grades of abrasive paper, followed by 4 grades of micro mesh that added up to a good 5 hours per sample. One of the challenges is to make sure you are not left with scratches all over your sample.
At the end this long process you should have a shiny smooth resin surface, and are likely to have repetitive strain disorder. But if, against all odds, you do succeed in preparing a beautifully smooth surface, the images you will get in return for your labour are really quite amazing!