How to mount your own wet microscope slides
A wet mount slide is one of the most common types of slide preparation techniques used in microscopy.
This guide walks you through the steps needed to prepare a wet mount slide for yourself. If you’re interested in microscopy, knowing how to mount your own wet slides is essential.
They’re most often used when looking at living specimens in a liquid or aqueous samples. Some common examples are plant or animal cells, and micro-organisms such as protozoa.
The main advantages of a wet mount are the ease of setup and the ability to observe living specimens in their natural habit. The main drawback is that they can’t be maintained permanently because the liquid will eventually evaporate.
A wet mount is simple to set up, but it can take a bit of practice to avoid air bubbles or spills. Here’s what you’ll need to get started.
Materials
- Glass slide
- Coverslip
- A pipette or dropper
- Water (if your specimens are from a freshwater pond or salty ocean, use that)
- Your specimen or sample
- Tweezers
- Paper towel
Method
- Using your pipette, place a small drop of your sample in the centre of a glass slide. If you have a dry sample, transfer some of it to the slide using tweezers then add a small drop of water.
- Using tweezers, take a coverslip and gently lower it at an angle until one edge is in the water. Then slowly lower the rest of the slide down until it’s resting flat on the slide. This approach lets you avoid air bubbles getting trapped under the coverslip.
- Use the edge of your paper towel, dab gently at the sides of the coverslip until any excess water is drained away. The coverslip shouldn’t be floating around – it should be sitting in place.
That’s all there is to it.
Slide preparation is a technique you’ll use often, but as you’ve seen, it can be performed easily with a bit of knowledge and a little practice.
Water isn’t the only medium you can use for a wet mount – you might encounter mounts using glycerin or immersion oil. Just be sure your organisms or samples are compatible with your medium before you try it yourself.
Tips
- If your specimens are swimming in and out of focus, there might be too much water on the slide.
- You can also have too little water – if your sample is drying out under your lights, you can add drops of water to the side of the coverslip.
- If you have trouble with evaporation, you can seal the coverslip to the slide using a sealant such as nail polish or Vaseline (petroleum jelly).
- If a dry sample you added to water is too clumped up, you can mix it up a bit with tweezers or a toothpick to make it easier to see.
- Try to avoid putting fingerprints on your coverslips – they’ll distort your image.