What Is A Laboratory Water Bath | Its Duties?

November 3, 2021

The Bath of Mary

The Bain-Marie is a laboratory equipment that is shaped like a container filled with hot water. The water bath is used to incubate samples in water at a constant temperature for a long period of time. All water baths have a digital or analog interface that allows users to set the desired temperature.

Applications include reagent heating, substrate melting, or cell culture incubation. It is also used to allow certain chemical reactions to occur at high temperatures. The water bath is a preferred heat source for heating flammable chemicals rather than an open flame to prevent ignition.

Different types of water baths are used depending on the application. For all water baths, it can be used up to 99.9 ° C. When the temperature is above 100 ° C, alternative methods such as oil bath, silicone bath or sand bath can be used.

Types of water baths

Baths of Maria with  circulation

Circulating baths are ideal for applications where temperature uniformity and consistency are critical, such as serological and enzymatic experiments. The water is thoroughly circulated throughout the bath, resulting in a more uniform temperature.

  • Circulation 30 – 70 ° C
  • Overboard circulation 70 – 100 ° C

Water baths without displacement

This type of water bath relies primarily on convection rather than evenly heated water. Therefore, it is less precise in terms of temperature control. Additionally, there are add-ons that provide agitation to non-circulating water baths to create more uniform heat transfer.

Bain-marie with transversal movement 

This type of water bath has an additional control for agitation, which moves liquids. This function can be activated or deactivated. In microbiological practices, constant agitation allows cultured liquid cultured cell cultures to be constantly mixed with air Constant agitation allows cultured liquid cultured cell cultures to be constantly mixed with air.

Refrigerated water baths 

For laboratories that require management of temperatures below ambient. Useful in refractometers, pasteurization, etc.


  • It is not recommended to use water baths with pyrophoric or moisture sensitive reactions. Do not heat a bath fluid above its flash point.
  • The water level should be monitored regularly, and filled only with distilled water. This is necessary to prevent salts from settling on the heater.
  • Disinfectants can be added to prevent the growth of organisms.
  • Raise the temperature to 90 ° C or higher once a week for half an hour for the purpose of decontamination.
  • Markers tend to come off easily in water baths. Use waterproof.
  • If the application involves liquids that emit vapors, it is recommended to operate the water bath in an extractor hood or in a well-ventilated area.
  • The cover closes to prevent evaporation and to help reach high temperatures.
  • Install on a stable surface away from flammable materials.
Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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