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How to Clean Laboratory Glassware

In a lab, glassware must be physically and chemically clean. For some labs, it must also be bacteriologically clean or sterile. In this blog post, Sonic Supply will look at how to clean laboratory glassware the right way, including which detergents to use, how often you should be cleaning and more.

How Often Should You Clean Lab Glassware?

As part of the maintenance of glassware in the laboratory, regular cleaning of items like beakers, funnels and flasks is critical. How often should you clean? The short answer: before and after each use.

Residue in the glassware obviously may affect the outcome of the task at hand. While it should have been washed after the previous use, don't assume. The safest assumption is that it hasn’t been washed.

Wash lab glassware right after use – with certain substances, if it's not cleaned immediately, it may not be possible to remove residue. If a thorough cleaning isn’t possible in the moment, soaking the glassware in water is preferable to doing nothing.

New glassware items are sometimes slightly alkaline in reaction. For precision chemical testing, soak new glassware for a few hours in acid water* before a regular washing.

* a 1 percent solution of hydrochloric acid or nitric acid

Hand-Wash or By Machine?

Whether you wash by hand or use a lab glassware washer, the important thing is that the glassware is cleaned properly. Different types of lab glassware may require different care (i.e., some may need to be soaked first, some may need to be sterilized, etc.).

Sometimes handwashing lab glassware is as simple as rinsing it with the proper solvent, followed by multiple rinses with distilled water, then a final rinse or two with deionized water. Other times, handwashing requires a lab glassware brush (available in a variety of sizes for cleaning glassware of different sizes and shapes) with a wooden or plastic handle that won’t scratch the glassware’s surface or cause abrasions.

When cleaning with a machine, consider the temperature. Always consult with the manufacturer’s recommendations for the proper cleaning temperatures of your glassware. Lab glassware washers can reach up to 93°C (199°F), which may be too high for some glassware.

Ultrasonic cleaners clean by imploding bubbles at frequencies such as 37,000 cycles per second (37 kHz) to safely remove contaminants from glass immersed in a cleaning solution. Sonic Supply carries metal baskets for use within ultrasonic cleaning devices. The cleaning temperature of approximately 60⁰C for ultrasonic cleaners depends on what’s being cleaned and the nature of the contaminants.

For steam sterilization, use an automated autoclave for up to 15 minutes at 121°C (250°F). Drying time shouldn’t exceed 15 minutes at 110°C (230°F).

Detergents & Chemicals for Cleaning Lab Glassware

A big part of understanding how to clean laboratory glassware is knowing what kind of detergent or cleaner to use. Often, detergent isn’t really necessary for cleaning labware, and you can instead rinse with solvents and distilled water, as we discussed above.

Chemicals used for cleaning lab glass products include acetone, ethanol and chromic acid. Which one you use depends on what type of glassware you’re cleaning and how you use that glassware.

Should you opt for detergent, choose one specifically designed for lab glassware, including brands like Liquinox, Sparkleen and Alconox. Avoid dishwashing detergents that you would use at home on dishes.

To Dry or Not to Dry?

Whether you choose to dry lab glassware depends on your preference and the specific situation. If you choose to dry, however, avoid paper towels or forced air. They often leave fibers or impurities behind, risking contamination of any solutions poured into the glassware.

Glassware can be left to air dry or, if needed for immediate use and it needs to be dry, rinse two or three times with acetone, which will remove any water and evaporate quickly.

The glassware can also be used wet unless it will affect the concentration of the solution to be used. If the solvent will be ether, rinse the glassware with ethanol or acetone to remove the water, then rinse with the final solution to remove them. The glassware may also be triple rinsed with the solution to be used.

After washing, your glassware looks clean to you, but how can you really tell? A deionized water rise will form a smooth sheet when poured through clean glassware; if it doesn’t, the glassware wasn’t clean enough and more aggressive cleaning may be required.

If you have any questions about how to clean laboratory glassware or need assistance in purchasing new glassware, call or email us. We’re here to help!

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