How to Clean Microscope Slides

By Sam Morgan
Microscope slides must be clean before you add a sample to ensure a good slide.

It’s important to thoroughly clean microscope slides after every use because otherwise you risk contaminating the slide the next time it’s used. Bits of the sample you use on this slide could mix with the sample used on the next slide and ruin it. Fortunately, cleaning slides properly takes only a small effort.



Washing Brand New Slides

Place a small drop of cleaning solution on each microscope slide. This can be dish washing fluid, or it can be a more specialized cleaning solution for slides, such as an ethyl alcohol solution.

Apply the soap uniformly across both sides of the glass with something that won’t scratch the slide, such as a lint-free microfiber towel.

Rinse the slide thoroughly using warm running water. Continue until all of the cleaning fluid is gone, including any extra bubbles that appear.

Blot the slide with a paper towel until it is dry. Alternatively, you can dry the slides with microfiber towels. Make sure that the towel you use is clean for each new slide. You may have to switch to a new towel after a certain number of slides.

Place each finished slide back into the slide case. Each case will typically carry 25 slides. Make sure that each slide goes into its proper place. If you try overloading the case with more slides than it can take, the slides could bang against each other and crack.

Washing Old Slides

Place all dirty microscope slides in a water basin full of warm water and detergent. Place them in the basin carefully so that none of them touch.

Leave the slides in the basin for an entire day. This should be sufficient time to allow the blood, oil or other material to loosen.

Use gauze to rub each slide individually on both sides until they are clean. Make sure you only leave the slides in the water for a few days at the most. If you leave the slides in water with detergent in it for weeks or longer, you risk letting the water evaporate. This will leave a detergent residue on the slides that will be difficult to remove.

Wrap cleaned slides in sheets of clean paper until they are ready to be used again. This allows you to store the slides closer together if a case isn’t available. Make sure to store slides somewhere dry. If you don’t, the slides will stick together due to humidity. You will then need to rewash the slides before they can be used, since they could be contaminated by the moist air.

Tip

Hold cleaned slides by the edges to avoid leaving fingerprints or oils on the surface.

About the Author

Sam Morgan has a master's degree in environmental science and policy. Morgan has been interested in science writing since childhood, and enjoys writing about anything relating to science since it's challenging and interesting to learn about our world.