Removing Specimens from Castable Mounting Media

Embedding specimens in mounting media prior to preparation offers many advantages. Mounting not only offers protection for both user and specimen, but also facilitates automation – to name only a few. However, errors may occur during mounting – e.g.  the specimen may be mounted upside down or at an angle. How do you get out of this predicament?

There are two ways in which this problem can be solved: You can either mount a new specimen or try and remove the existing specimen from the mounting compound. Given that most mounting media are relatively hard and brittle, the simplest method is usually to clamp the specimen in a vise. Apply pressure on the mounted specimen, until the mounting compound cracks away. Be sure to wear eye protection during the process, to avoid fragments getting into your eye. The amount of force required can be reduced by notching the specimen beforehand.

 

Figure 1: A: Specimen prior to mounting; B: Mounted specimen; C: Specimen in the vise; D: Specimen after removal
Figure 1: A: Specimen prior to mounting; B: Mounted specimen;
C: Specimen in the vise; D: Specimen after removal

You should also consider whether or not you are dealing with a delicate the specimen – fragile and thin specimens may be damaged by the above method. These specimens are better removed from the mounting compound by cutting.

Thermoplastic mounting media such as e.g. TransOptic from Buehler may be molten in order to remove the specimen. In this case, however, be aware that the specimen may be sensitive to temperature and the microstructure of the material may be affected by the heat.

Figure 2: A: Specimen mounted in TransOptic; B Specimen after removal
Figure 2: A: Specimen mounted in TransOptic; B Specimen after removal

There is another way in which specimens can be removed from mounting media: Certain types of mounting media may be softened by the use of solvents such as acetone. However, this requires certain safety precautions.

In summary, when removing a specimen from mounting media, you should consider the sensitivity of the specimen to pressure, temperature or solvents, and the type of mounting media used.

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