High Refractive Index Mounting Media

(updated 8/14/2011)

Many of the high refractive index mounting media that were used for diatom slides in the past are now unavailable.  I have developed a high refractive (1.70+) index mounting medium that is useful for mounting diatoms.  This material has been named Zrax and is a condensation product between naphthalene (Enoz old fashioned moth balls) and formaldehyde (Formalin MS - used as an aquarium treatment). Zrax is similar to Hyrax, which is no longer available, and Naphrax.  It is reported that Naphrax was unstable over time and deposited droplets, thus spoiling the hard work involved in making the preparation. Zrax has shown no such problems and produces a beautiful preparation. Zrax is dissolved in toluene and is a clear very light yellow material with a refractive index of greater than 1.70 in the solid.  It makes excellent diatom mounts and is used for arranged diatom slides in addition to strews. For a descriptive page on Zrax in pdf format, click here. For an excellent article on making strew and selected diatom slides by Jim Solliday, click here.

One ounce bottles of Zrax without solvent are $40 postpaid from me(Bill Dailey).  Larger quantity 200 gram bottles are $225 plus postage. Email me for your requirements. Klaus Kemp (www.diatoms.co.uk) is a reseller for the UK and the European Union. Contact Klaus for details. You will need to add toluene or other organic solvent to dissolve the resin before use.  Toluene may still be available in your local hardware and paint stores as a thinner or degreaser. Toluene can not be sent in the US mail system. If you are unable to locate toluene, you can substitute Xylene (Xylol). However you will need to warm your slides to a slightly higher temperature to cure them since xylene boils at a higher temperature than toluene. Another solvent you can use is pure acetone. Make sure that you use pure acetone and not a product that has water in it or that will spoil slides. DON'T use alcohol or turpentine or mineral spirits, etc. They won't dissolve the Zrax and will cause problems.

Another excellent diatom mounting medium is Styrax which has a refractive index of 1.58. It is especially useful for highly silicified forms like those found in fossil marine samples. It is available from Dr. Stephen Nagy who maintains the Montana Diatoms page. Other information and products related to diatoms will be found here, as will some beautiful pictures of spectacular arranged diatom microscope slides.

In the past I offered Pleurax but I am no longer able to make it because it causes me a severe allergic reaction similar to the blisters caused by poison ivy.

   zrax200g             zraxlabel