How to clean immersion oil from your 100x objective lens

If you use 100x OIL objective lenses, you need to know how to properly clean immersion oil off your equipment.

Keeping your lens clean and oil-free will prevent residue build-up, lens degradation, and accidental damage to your other objectives.

Here are some tips to help you keep your microscope clean and in good working order. 

Only use lens paper

Can you use a regular tissue or a paper towel to wipe off immersion oil? The answer is definitely not. Resist this urge if you want to keep your objective lens intact.

Special purpose lens papers are soft, lintless and non-abrasive. Anything other than microscope lens paper will be too coarse and can easily scratch the lens. You’ll be left with a distorted image and the cost of a replacement objective.

Remove the oil straight away

Start cleaning immediately after use, before the oil solidifies.

If you wait too long, the oil will dry and harden. Not only is it then harder to remove, but it will catch stray dust and particulates that will impair your image quality. If left untended long enough, the oil can even begin to degrade your lenses.

Oil removal technique

There are 2 preferred approaches to wiping fresh oil off an objective.

Some manufacturers recommend a single swipe of lens paper in one direction, while others suggest a gentle blotting approach.

Wipe or blot, always remember to use a fresh and un-oiled part of the lens paper with each pass or you’ll be cleaning forever.

Removing hardened oil

If your lens is covered in hardened oil, you’ll need an appropriate solvent or lens cleaning solution. 

Place a small amount of lens cleaner onto a piece of lens paper and then gently and slowly (to allow time for the oil to soften) wipe the lens from the centre outwards in a spiral.

Repeat as needed until no oil is left.

Don’t use the same lens paper to clean the other lenses

It’s sometimes suggested that you should use the same piece of lens paper you just used to remove immersion oil to clean your other objective lenses. Don’t do this.

The only thing this will accomplish is to cover your dry lenses in oil, which can lead to serious and expensive damage.

Protect your 40x objective

A common issue when using or cleaning off immersion oil is accidentally swinging the 40x objective into the oil on the slide that was just in use.

Make absolutely sure that you either remove the oily slide before you clean your lens or take care to not rotate the 40x completely into position.

Unlike the 100x objective, the 40x is not properly sealed against oil and it will inevitably get inside the lens where it will ruin your image quality. Your only option then will be an expensive replacement.

Check with the manufacturer

If you’re unsure which solvent, oil or cleaning approach is right for your microscope, it’s a good idea to check with the manufacturer.

Cleaning products and approaches aren’t one size fits all. Taking the time to make sure you have the right supplies and technique could prevent accidental damage to your expensive lenses.

Upgrade to a new 100x DRY Objective

Read more about our new 100X Semi Plan DRY Objective - NEVER use oil again