How to Make a Wet Mount Microscope Slide

By Techwalla Electronics Editor

A wet mount slide is the most common type of slide preparation for microscope work. Wet mount slides are used to view living organisms, as well as liquid substances of all kinds. They are also used for any sort of specimen that needs to be kept moist. If you work with microscopes or are planning to start, you should learn how to make a wet mount microscope slide.

Things You'll Need

  • Medicine dropper
  • Petroleum jelly
  • Cover slip
  • Flat glass slide

Step 1

Use a flat glass slide to prepare a wet mount. The slide should be clean and free of dust or other fine particles.

Step 2

Suck up a few drops of your liquid specimen into a medicine dropper.

Step 3

Pick up a flat glass slide with one hand, grasping it by the outer edges.

Step 4

Place one drop of the liquid specimen in the medicine dropper on top of the slide. Make sure the drop goes on the center portion of the slide.

Step 5

Put down the medicine dropper. Do not tilt the slide in your other hand while you are doing this.

Step 6

Use your free hand to carefully pick up a cover slip (they are extremely fragile). Grasp the cover slip by the outer edges.

Step 7

Place the cover slip on top of the slide, making sure the edges of the cover slip match up with the edges of the slide. Do not press down on the cover slip.

Step 8

Continue to grasp the slide/cover slip combination by the outer edges. You should keep the slide as horizontal and steady as possible, and place it on the viewing tray of your microscope.

Tips & Warnings

  • Most wet mount microscope slides dry out in about half an hour.
  • You can make the liquid specimen in your wet mount microscope slide last longer by applying a thin layer of petroleum jelly to the outer edges of the cover slip. Press very gently at the edges when you place the cover slip on top of your slide. This creates a seal that will keep the liquid on the slide from drying out too quickly. Liquid on slides with a petroleum jelly seal usually lasts for 1 to 2 days.
  • Using just the right amount of water is key when you make a wet mount microscope slide. If you don't use enough water, the water will not support the cover slip, which could cause the cover slip to kill any living organisms in the water. If you use too much water, the cover slip will not stay on the slide.