Walk into almost any laboratory and you will see shelves lined with colorful bottles, cans, and boxes. These containers hold the lifeblood of the lab—chemicals for testing, analyzing, staining, and preserving. But with this essential arsenal comes a significant responsibility: storing and labeling chemicals properly. Unfortunately, this is one of the most common safety gaps I see when I visit labs across the country.
When chemical labeling and storage are overlooked, accidents follow. From mislabeled bottles of solvents that led to dangerous mix-ups, to acids stored next to bases that caused near-miss reactions, it all happens. The truth is, labeling and storage may not be the most exciting part of laboratory safety, but they are among the most critical.
OSHA’s Hazard Communication Standard is clear: every container of a hazardous chemical must be labeled. That means not just the original manufacturer’s container, but any secondary container as well. Labels are not just a regulatory box to check—they are a lifeline. In an emergency, when seconds count, a proper label tells responders what’s inside, how to handle it, and what to do if something goes wrong.

Chemical labels must include, at minimum:
• The chemical’s full name (not an abbreviation only one person understands).
• Hazard warnings (flammable, corrosive, toxic, etc.).
• The name and address of the manufacturer or the lab preparing the mixture.

GHS (Globally Harmonized System) labeling takes it a step further by including standardized pictograms and signal words. The red diamond with a flame instantly communicates “flammable.” The skull and crossbones leaves no doubt about toxicity. These universal symbols mean that no matter who walks into your lab—an inspector, a visitor, or a new employee—they can quickly understand the risks.

The place where labeling breaks down most often is with secondary chemical containers. These are the bottles, beakers, squeeze-bottles, or flasks that chemicals are transferred into for everyday use. Staff often think, “I’ll only be using this today” or “I’ll remember what this is.” But chemicals have a way of sitting around longer than intended.
If you see countless clear squeeze bottles with mysterious colorless liquids; is it ethanol? Bleach? Water? Without a label, there’s no way to know. That’s a recipe for cross-contamination, ruined experiments, and potentially dangerous exposures.
The rule is simple: if you take a chemical out of its original container and put it into another, you must label the new container immediately. The only exception is when the chemical is used right away by the person who transferred it, and it never leaves their control. But in reality, that’s rare. Once the phone rings, the doorbell buzzes, or another task distracts you, that “temporary” container is forgotten.
For secondary containers, a label doesn’t need to be elaborate, but it must be clear. At a minimum:
• The full chemical name.
• Primary hazards (flammable, corrosive, oxidizer, etc.).
• Date of transfer (especially important for peroxide-forming chemicals or unstable reagents).
Some labs use pre-printed labels with pictograms, others use tape and a marker. The format doesn’t matter as much as the accuracy and clarity.
Once chemicals are properly labeled, they need to be stored correctly. Storage mistakes can turn a safe lab into a dangerous one quickly. Oxidizers should not sit on the same shelf as flammables, acids should not be right next to bases, and nitric acid needs to be kept away from solvents. These are disasters waiting to happen.
Segregate by hazard class, not alphabetically. Alphabetical storage can put acetone (flammable) next to acetic acid (corrosive). Instead, store flammables together, acids together, bases together, oxidizers separately, and toxics in their own area.
Use appropriate cabinets. Flammable chemicals belong in flammable storage cabinets. Corrosives like strong acids should be in acid cabinets with corrosion-resistant linings. Toxic chemicals should be locked when not in use.
Avoid storing chemicals on the floor or above shoulder level. A spill from overhead can cause serious injury, and containers on the floor are more likely to be kicked or knocked over. Label storage areas. Cabinets and shelves should be labeled by hazard class to help staff put chemicals back where they belong. Mind expiration dates. Some chemicals, such as ethers, form explosive peroxides over time. If they sit forgotten in the back of a cabinet, they can become unstable and extremely hazardous.
The science of labeling and storage is straightforward. The challenge is the human behavior around it. People skip labels because they’re in a hurry. They put chemicals back in the wrong place because they don’t know the system. Or, worst of all, they assume “someone else will fix it.”
Creating a culture of accountability is essential. Train staff not just on the “what” but on the “why.” Share stories of real accidents caused by mislabeling or poor storage. Encourage staff to speak up when they see a container without a label or a chemical stored incorrectly. A peer-to-peer reminder in the moment can prevent a serious incident.
Chemical labeling and storage may not make headlines, but they are cornerstones of laboratory safety. A clearly labeled bottle can prevent a dangerous mistake. A properly stored chemical can stop a violent reaction. Every label is a communication tool. Every storage practice is a protective barrier. Together, they ensure that your lab operates safely, efficiently, and in compliance with regulations.
The next time you pick up a squeeze bottle or place a reagent on a shelf, ask yourself: if I wasn’t here tomorrow, would someone else know exactly what this is and how to handle it? If the answer is no, then it’s time to fix the label—or the storage. Safety isn’t about luck; it’s about the choices we make every day in the lab.

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