What Kind of Microscope Cover Glass can be used for Automatic Coverslippers

microscope cover glass

Microscope slides, cover glasses, and automatic coverslippers are the starter pack of microscopy. There is a lot to know about this field before you are ready to use it. And the best way to learn is to ask questions! The question regarding microscopes that we are exploring today is: what kind of microscope cover glasses can be used for automatic coverslippers?

For an automatic coverslipper, an ideal cover glass shall have the following qualities.

  1. Good flexibility 
  2. Uniform Thickness and size
  3. Material that is not sticky.

Before we dive into the discussion of this seemingly complicated question, let us break down the terms used:

What is a microscope cover glass?

A microscope cover glass is a thin sheet of glass that covers a microscope slide when an object or substance is placed on it for observation, under a microscope. It can be square, circular, or rectangular, depending upon the need or nature of the specimen. The region of focus of the microscope being used may also be a contributing factor.

Standard Thickness:


Standard square and rectangular size (mm):

18×18mm, 20×20mm, 22×22mm, 24×24mm, 24×32mm, 24×40mm, 24×50mm,  24×60mm

Standard Circle size (mm):

Φ8, Φ10, Φ11, Φ12, Φ13, Φ14, Φ15, Φ16, Φ18, Φ20, Φ22, Φ24, Φ25

Other special thickness, size is also available.

Why is it used?

When it comes to samples being tested in a laboratory, it’s no surprise that they should be kept as close to their original form as possible.

The need for a cover glass is present in certain circumstances only. A cover glass is used when there is a possibility of the sample coming into contact with the objective lens of the microscope under which the slide is placed. It is also used when the sample is wet mounted and its thickness may prevent it from being viewed with clarity under the microscope.

Besides keeping liquid samples on the slides in a flat layer with maintained thickness over time, cover glasses also serve the purpose of keeping the solid samples safe on the slides when in storage. Dust particles and oxidation are only some of the many obstacles that may cause the results to be inaccurate. This is where a cover glass is used for the protection of the sample. To secure a sample on a microscopic glass, a cover glass is placed on top of the slides with the sample pressed in between.

The proper way of doing so is placing the glass on one corner of the slide, as if it is hinged there, and then lowering it to cover the specimen. The liquid sample will force out any air present and the cover glass will stick to the slide as it should. This ensures no air bubbles are trapped inside. Although a small air bubble is nothing to worry about but a big one or more than one can make it difficult to observe the sample. If you practice it enough, it’s a simple process that you can nail.

But what kind of microscope cover glass can be used for automatic cover slippers? Let us first see what automatic cover slippers are:

Automatic Coverslipper: the Helpers

The usage of microscope slides for the sampling of cells is an important and common procedure. Microscope slides are used everywhere – in forensic labs, for cancer research, pharmaceuticals, Covid-19 testing, pathology, genomics, and more. Sometimes, it gets difficult to carry out the whole process of sample placement – especially when it’s all done manually.

Think about it. Laying out the slides in hundreds, placing the sample on the slides, and then finally adding the cover glass on each of them – one by one, carefully. To save time and effort, the last step can be performed automatically, through an automatic coverslipper.

An automatic coverslipper is a machine specially designed to slip on a cover glass over slides with samples on them. Some of these machines can take 30 slides at a time while others have a high capacity of up to 600 slides. The settings can be set out manually by the operator (Wet or dry mount) and the rest is taken care of by the machine.

The process of slipping cover glass looks like this: A suction cup system brings the cover glass to the mounting site, where another electronic arm brings the microscope slide, and the two come together in a way that avoids any air bubbles building up in the sample. 

Now that we know what a microscope cover glass is, why it is used, and how it comes into play with an automatic coverslipper, we can come to the most important question:

What Kind of Microscope Cover Glass can be used for Automatic Coverslippers?

It is important to use the right cover glass in coverslippers since a jam in the machine can be messy and result in the loss of important samples. To avoid such circumstances, using ideal cover glasses may go a long way.

The glass material matters as it directly affects the flexibility and thickness of the cover glasses. The kinds of glass materials that are good for automatic coverslippers are soda-lime glass, super white glass (also called float glass), and borosilicate glass. Borosilicate glass coverslips are considered best for automatic coverslippers but other materials can be used as well. This glass is colorless and does well with fluorescence microscopy too.

Since the process is automated, we need to make sure that the cover glasses inserted in the machine are of good quality, have the right thickness, and are flexible. These characteristics will ensure that there are no breakages, suction doesn’t damage any apparatus, and accidents are minimized.

The technology with which cover glasses are cut also makes a difference. Smooth edges and uniformity of size make hassle-free covers that work well with the automatic coverslippers. If the glass is roughly cut or uneven in size, it may create a disturbance in the machine. Hence, uniformity of the cover glasses is vital.

Lastly, to avoid stickiness in the machine, finely powdered glass may be used on the surface to prevent any jams.

The size of cover glass used on coverslipper is usally big size like 24×50mm and 24×60mm.

Most popular coverslipper:

Leica, Dako,Sakura


Sample readings are extremely important procedures in today’s world. They deal with sensitive data which should be observed efficiently as inaccurate results may cause huge losses. While manpower is replaced with automatic procedures, we are still responsible for dealing with machines in a way that reaps the best results for us.

For machines to last longer and give accurate results, the best operators can do is insert items that are ideal for the machine to function properly. Even the most helpful machines need maintenance and professional handling. In the lab, the same applies too.

We can ensure smooth cover glass placement on microscope slides via an automatic coverslipper by using the right kind of cover glass material. If what we give the machine is not right, the machine will not give us what we need; it’s a two-way street. This article was aimed at addressing all the important points one should consider while using microscope cover glass for automatic cover slippers and we hope it cleared out all your confusions too.

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