Cleaning Microscope Lenses

The best way to avoid having to clean the lenses on your microscope is to use it carefully and keep it covered when not in use. If a lens gets dirty or gummed up, here's what you should do.


Most microscope specialists say the less cleaning of a microscope lens, the better. Eventually, the time will come when you will have to give them a good cleaning. Below are some tips on how to correctly do this.


First, try to locate the dirt. Is it on the eyepiece lens or objective lens? If you see a spot when looking in the microscope and you see it at all powers it's probably on the outside of the eyepiece lens. If your eyepiece lens turns, turn it and see if the spot moves as well. If so, the dirt is on the eyepiece lens (if not, the dirt is internal and you should probably have it cleaned by a professional). If you only see it at one power, the dirt is most likely on that particular objective lens.


Sometimes all you need to do is blow off the residue. Use a squeeze bulb or one of the camera lens cleaner bulbs with the camel hair brush on the end. If you need more, you can use the compressed air cans that are sometimes used to clean computer keyboards. Do not use any sprays with cleaners. Once blown clean, lightly wipe the lens with Kimwipes or another approved lens cloth.


Another good cleaning tissue is Kodak Lens Tissue (available at photo stores) In lieu of a brush, you can use the paper. Roll the tissue into a tube and tear it in half, with the feathery torn ends together. Use it as a one-time brush. Use several for very dirty lenses. A regular lens brush can hold grit and cause scratching. If the grime is still there, you will need to use a solvent.


When using solvents, put a drop or two on the paper then hold it against the lens for a few seconds to dissolve the crud. Then lightly wipe it free. Distilled water is the first solvent recommened. If that does not work, try alcohol. Isopropyl alcohol is one of the best solvents but it must be at least 90%+ pure (do not use rubbing alcohol, 30% water). Everclear which is grain alcohol (you must be 21!) can also be used but it doesn't do as well in dissolving crud. If you have something like Balsam stuck on the lens, you must resort to a stronger solvent like Acetone or Xylene.


Acetone should never be put on plastic parts as it dissolves most paints and plastics. A lens cleaning solution such as that in the Microscope Cleaning Kit works well for cleaning lenses. Some people swear by a solution called ROR, although we have never tried it. When adding the solvent, put only a small amount on the kimwipe and always apply it from the underside going upward to the lens. This will keep the liquid from running down into the lens. Do not remove the lenses from the instrument unless absolutely necessary.


If you are using a 100x objective with immersion oil, just simply wipe the excess oil off the lens with a kimwipe after use. Occasionally dust may build up on the lightly oiled surface so if you wish to completely remove the oil then you must use an oil soluble solvent. For the Cargille Type A or B immersion oil that we sell, you can use Naptha, Xylene, or turpentine (use very small amounts on the kimwipe). Do not use water, alcohol or acetone as the oil is insoluble to these solvents. To remove other oily substances, we recommend using the detergent called Wisk and prepare a solution of 1 part Wisk to 100 parts water.


Try not to remove the lenses from your microscope unless absolutely necessary and remember to keep it covered as dust is the number one enemy!