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How to Effectively Defrost a Laboratory Freezer in 5 Steps

Defrosting your laboratory freezer may seem like a tedious process. However, it is a necessary task for preserving the life of your freezer, ensuring the proper temperature, and making sure there is plenty of space to store specimens instead of ice. Your freezer should be defrosted at least once a year and more often if there is a buildup of more than three-eighths of an inch of ice on the inner and outer compartments of the unit. Manual defrost freezers need about two days for the defrosting process, and the actual defrosting part will ideally start in the morning so that you can monitor run off throughout the day to prevent water from creating a puddle on the floor that could cause people to slip. Read on for the five steps to defrosting your lab freezer.

  1. Preparation: Preparing to defrost a laboratory freezer involves communicating your intentions to your entire team as well as your building maintenance personnel. Choose a date as to when the defrosting will take place and provide reminders that anything that remains unlabeled in the freezer will be disposed of. This will allow everyone time to ensure that their samples are properly labeled and prepared for transfer to the backup freezer and samples that are no longer needed are disposed of. Care should be taken to ensure that any hazardous materials that have been stored in the freezer are properly identified and that the ice buildup has been tested for remains of those hazardous materials before the defrosting process. Follow the proper safety protocols for the removal of ice containing hazardous materials. For all other ice buildup, proceed with the steps below.

  2. Transfer: After determining that the backup refrigerator has space for the temporary storage of contents from the unit you’re planning to defrost, quickly transfer temperature sensitive samples, ensuring that they’re properly labeled and coded so that they can be easily located during the defrost process and properly moved back over once the process is complete. Samples should be transferred in small batches in order to avoid holding the freezer door open for long periods of time, thus causing the freezer to warm up prematurely and placing samples remaining inside of it at risk for spoilage.

  3. Unplug the freezer in the morning and establish a wick and reservoir system so that you can safely contain the water from the melted ice. Building maintenance personnel should place cautionary signs in the area so that people are aware that the defrost process is taking place and are aware that the process may cause water to puddle on the floor.

  4. Once the ice has been melted, it is time to clean. Be sure to use gloves during the process. Use a 10 percent bleach cleaning solution — as required for safe storage of biohazard materials. Working in a top-down approach, clean both the inside and outside of the freezer. A spray bottle with warm water and a squeegee can be used in order to carefully clean dust and debris from the wire coils and racks that contain the heating elements. If there is still remaining ice and it has fallen off in large chunks, properly dispose of these chunks. Never use a knife to attempt to hack or scrape ice away as this can severely damage your freezer.

  5. Plug in the freezer and allow it to reach the desired temperature. Ideally, this can take place overnight. Once it has reached the temperature that your samples require, retrieve the samples from the backup freezer and return them to your lab freezer.


  • Once you’ve completed the defrosting process, you will want to make sure that everyone on your team is aware of proper labeling and organization techniques that can both assist you in keeping the freezer working properly and assist team members in being able to locate the samples they need, when they need them.

  • If you find yourself needing to defrost your lab freezer more often than normal, you should suspect that your freezer seal may be working improperly, which will allow more air to enter the freezer and cause a buildup of condensation. Have the seal inspected. Other causes for frequent ice buildup include high usage involving the door being opened often. You may want to shift items that are frequently retrieved and rely less on an exact temperature to a high traffic area, and allow your lab freezer’s contents to receive the benefits of being placed in a unit that involves less traffic. Having a unit with a glass door can also prevent people from opening the door as frequently, reducing the condensation that causes ice to build up.

  • Remember that warmer rooms and warmer, humid summer months may also cause ice to accumulate faster, as will freezer with fewer contents contained inside of them.

  • Are you interested in obtaining a freezer with auto defrost so as to avoid the defrosting process? American Biotech Supply has a number of different varieties of glass and solid door laboratory freezer with auto defrost functions. We even have under and over the counter models for small spaces and chest models for long term storage. If your work requires the use of a manual defrost freezer , we have units available with that feature, as well. It is important to remember that the older the freezer is, the older the gaskets on the door are. This means that an older unit may require the defrosting process to be completed more often. Additionally, older freezer contain refrigerants that are harmful to the environment, while many of American Biotech Supply’s new models come with environmentally friendly refrigerants that are in compliance with national and global initiatives.

  • Minimize cold air loss by providing each user with his or her own designated compartment for sample storage. This makes the task of retrieving samples from the freezer faster and provides additional organizational benefits to all of the users at the same time.

For more information or for questions about American Biotech Supply laboratory freezer units, contact our dedicated and knowledgeable customer support representatives.


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