Needless to say, the preferred method of reducing air bubbles depends on the characteristics of the specimen. Try out the following possibilities.
- Cover slip placement: Lower the cover slip on the water droplet with an angle. This permits air to escape on one side.
- Water placement: If the specimen is not fully submerged in the water droplet, add another droplet on top of the specimen before lowering the cover slip. Alternatively you can also place a drop of water on the cover slip itself, before it is lowered on the specimen.
- Alternative mounting medium: Use a mounting medium other than water. Try immersion oil, nail polish or Euparal as a mounting medium. These mediums are hydrophobic and may therefore interact better with other hydrophobic specimens (such as bird feathers, fur, etc).
- Break the surface tension: Add a small amount of detergent, such as soap. This will break the surface tension of the water. The water will therefore adhere better to some specimens, thus preventing bubbles. The soap may also harm some water organisms, however.
- Apply a vacuum: You can remove air bubbles by placing the slide into a vacuum. THe bubbles will expand and move out beneath the cover glass.
- Dehydrate the specimen: Place the specimen into alcohol. Some specimens will shrink and lose water and air. By placing the specimen into water again, the specimen will take up the water.
- Remove oil and fat: Wash the specimen in alcohol. This will make the specimen less hydrophobic.
- Add water: Air bubbles also form when the water starts to dry up. If the air bubble is large and reaches the side of the cover glass, you can add more water from the side of the cover glass.