It never ceases to amaze, the capacity of people to complicate simple things. -K
When the microscope enthusiast is starting out they generally begin with the sorts of objects which may be collected and prepared with what’s on hand. Eventually they may find that there is a clear and drastic line that must be at some point crossed, the supply familiarity line. Some of the consumables used in microscopy are more available these days than previous, distilled water for example, others far less, camphor and red lead come to mind. While the present day MSDS and GHS standards provide an accessible method of understanding the nature of the chemicals involved, and the internet a means of finding them, there is still a greater barrier provided by the marketplace: language. Simply put: people love a synonym, but a duvet is not just any blanket.
Today I needed to replenish a few of my supplies, and one of them being turpentine, I was reminded of something from my art-school days, “the art store argument”. This argument goes as follows: “A pint of turpentine costs $20.00 at the art store, and $5.00 at the hardware store. Where should one shop?” The initial reaction is likely to be “The hardware store! I can buy a bunch of other stuff with the money I’ll save.” To this the teacher or old-hat will smirk and say something to the effect that “Absolutely not, the turpentine from the art store is of a higher quality and standard, it’s just what you’ll need and will give you results that are well worth the cost. Besides, everyone knows the hardware turpentine smells like embalming fluid.”
At this point I’ll take a minute to say that turpentine was once only one of two products obtained by processing the sap from a variety of species of the genus Pinus. When this sap is refined the distillate is a volatile solvent of primarily, terpenes, that is called turpentine. The residue of this distillation is a solid pitch resin called rosin-the stuff violinists use on their bows. Presently, terpenes can also be extracted from other compounds that contain them in much lower concentrations than are found in pine sap. That method will produce a functionally similar product primarily composed of terpenes, but will contain a significant amount of other VOC’s. In the United States, the name “Gum Spirits of Turpentine” is actually restricted for use with products which are produced from Pinus spp. by distillation, specifically so it may be set apart from other terpene based solvents. The two and a half fluid ounce bottle of turpentine one can buy for $4.99 at the art store, is functionally identical to the $5.00 pint from the paint aisle at the hardware store, it’s produced from the same source, by the same method. Anyone who has experienced the headache and sworn off using cheap turpentine has been using a terpene product that is not “Gum Spirits of Turpentine.”
This brings me to my point and the bane of many facing the supply-gap for the first time, language. If reading along in a book, Dr. Carpenter describes a method for mounting a specimen one would like to try that makes use of “Venetian Turpentine,” the reader should absolutely not rush out and buy a gallon of turpentine. A few minutes consulting a dictionary will reveal that Venetian Turpentine is in fact quite different from anything we have discussed thus far. Venetian Turpentine is a terpene distillate produced from the sap of the Western Larch. It’s suitable as a resinous mountant.
When looking for supplies It’s important to know what one needs before one searches it out for purchase. It doesn’t matter if one purchases Xylene as a safer alternative to Benzene or Histo-Clear as a safer alternative to Xylene, what matters is having an understanding of what the substance is required for. The best way to find out what the substance is required for is to understand the process for which it is being used. Once the process and the part played by the substance is understood look to a dictionary, not the internet, not a blog or a forum, a dictionary. Common use is far more flexible than even contemporary dictionaries and is far less reliable. A quick look at a dictionary (which would make the distinction between turpentine and Gum Spirits of Turpentine) cold have saved this old student a bundle. Once one is familiar with the requirements of the substance, and knows what the substance is specifically called, it’s much easier to seek it out with confidence.