I’m constantly amazed at the ease with which one can obtain certain chemicals; in the old days you had to know the right people, now you just have to know how to search the web. Of course in the very old days your local pharmacist would just give you some… -K
The slide I’ll describe today is very much the same as the previous, differing only in the treatment one uses prior to mounting. While very fine results may be had by the process described previously, a little more effort can deliver a superior preparation. This method is not the acme of hair mounts either. There is seemingly always a little bit of improvement that one can make when it comes to mounting. Once one begins to gain a degree of comfort and familiarity with the process, ideas for improvement abound. The successful student is one who does not see the procedures of others as a rule-book but as an inspiration.
Hair is among the materials that could be mounted directly into resin after collection. In the previous entry that is very nearly what was done. A brief rinse in alcohol was performed primarily to ease manipulation, rather than to provide for dehydration as one may have reasonably guessed. Fortunately, the composition of hair is such that even freshly collected hair is essentially “dry” to begin with. Natural oils are the primary moisture in any hair and this oil will have some effect on the refraction of the mounting medium after the slide has cured. To provide a better level of resolution of the margins of a strand of hair one must remove the oil from the hair so that the refractive index of the mountant is uniform.
Most every microscopist will posses a number of solvents that may be used with success to clean a hair of oils prior to mounting. One solvent in particular enjoyed a profound popularity, for this purpose and others fifty years ago: ether. Sulfuric ether (more apt to be found today as ethyl or diethyl ether) is a highly volatile inflammable solvent. It is heavier than air and has a rather distinct odor that is markedly less beckoning than chloroform, neither of which one should inhale, and both of which have their uses in microscopic mounting.
The distillation of sulfuric ether is not complicated and is one of the more common bits of home chemistry achievement one sees on various web sites. Do not attempt the distillation of sulfuric ether at home without the proper training. Far too many people have far too high an opinion of their abilities and will run into all manner of problems. I have seen videos of ether being distilled on kitchen hot-plates that make me marvel at the fortune of others in not catching fire. Ether is available from many reputable chemical supply houses at a very economical cost. If one is unable to locate ether, various similar solvents may be used. Xylene and toluene are effective substitutes if local laws or personal caution dictates.
To remove totally the natural oils from a sample of hair one should make a solution of one part sulfuric ether to one part anhydrous alcohol. This is one of the situations where I do not recommend the use of denatured alcohol as an alternative to anhydrous alcohol. Some formulations of denatured alcohol may provide suitable results, but as the amount of solution required is very small, anhydrous ethanol can be used without it being a great waste. Alternatively, one may use anhydrous isopropanol or even anhydrous methanol, though isopropanol is likely to be the most readily available and least expensive. Be sure to mix the solution in an amber glass vial as ether has the potential to form hazardous peroxides in the presence of light.
With the ether-alcohol solution prepared, take in a forceps the hair to be mounted and carefully agitate it in the vial for from forty to sixty seconds. Afterwards deposit the hair very near the center of a clean slip and mount it as described in the previous post. As mentioned previously this treatment will remove the natural oils from the hair and allow for the mountant to form a material of uniform refractive index around the hair. This will permit the scale pattern, and interior structure of the hair to be observed somewhat better than that of a hair which is mounted directly, or through alcohol and a clearing agent alone. It it will not provide as clear an image of the scale pattern as a scale cast, but that is another sort of slide entirely.