Dried oil is not only difficult to remove from an objective lens, but this sticky substance can easily trap dust, dirt, fingerprints and other contaminating particles. A little embedded dust can affect the image quality and cause optical errors such as shading or blurry images and eventually affect the front lens of the objective.

For this reason, we recommend removing immersion oil from your lenses immediately after use: the oil will still be wet.
A real danger if not kept clean is that an analyst can subconsciously contaminate samples and contaminate other lenses with oil residue.

By following the cleaning steps, you ensure that the microscope is ready for the next time.
This saves time.

Objective front lenses are usually very small: it can be difficult to see dust on the lens. Fortunately, we have a handy trick for this.

Remove the eyepiece from the microscope and turn it upside down towards the objective lens until you see the front lens in focus. Tthrough the eyepiece you now can see any contamination you need to remove. Alternatively, you can use a loupe.

Sometimes an objective is attached too tightly to the microscope to remove for inspection and cleaning. In this case, set the objective at an angle where you can easily clean the lens.

Now that you have inspected the lens, begin the cleaning process. At first use a “blower” to remove dust particles from the objective lens without touching it.

Now take a new piece of lens paper and fold it to make a point. Keep in mind that how you fold the lens paper depends on the size of the objective front lens.

For large objectives, fold the lens paper into a square. This makes it easy to wipe the entire lens surface clean. Perform this technique in four steps, as shown in the images below:

Many objectives are small: your finger may be too big to wipe the lens surface. In this case, make a triangle with the lens paper to make a point. If this does not work, you can wrap a lens paper around a skewer (blunt side).

Remember, always use lens paper, not tissues. Consumer wipes contain loose, coarse fibers that can scratch the lens surface; they can break off and remain on the lens.

Then moisten the lens paper with a suitable solvent that can dissolve the oil and clean the lens.
We recommend HyperClean from our Professional Cleaning Toolbox. If you do not have this available now, a mixture of alcohol / ether (30% / 70% respectively) may also suffice. Use alcohol 98% for this: a commercially available liquid.
Keep in mind that these cleaning solutions are flammable.

Now take the mooist lens paper and wipe the lens from the center outwards in a spiral pattern. This technique moves dust or dirt to the outside.

Use the eyepiece or magnifier to check your act for any residue. If there are still traces of immersion oil, repeat the act until everything is clean. Always use a new lens paper.

An advantage of the spiral wipe technique is that you can use it to also clean other optical surfaces, such as a camera lens, condenser lens or glass plate. If the surface is too large for your finger to wipe, hold the lens paper on the surface while rotating the objective by touching only the edges.

The image below shows how to use this technique to clean a filter.

After cleaning an optical microscope accessory, always check for any residual dust or immersion oil with an eyepiece or loupe. Then immediately reattach the cleaned part to your microscope to keep the system complete.

We are aware that your time is valuable, however: removing oil from your objectives can ensure consistently good image quality and avoid costly repair of your equipment.
If you are concerned about your instrument, you can always contact us.
We are happy to assist you further.