When you are handling any sort of chemical, it is important to know the risks associated with it. Fortunately, over the years a sort of shorthand has been developed to communicate this information to you in the form of various symbols.
National Fire Protection Association Warning
First, we have the National Fire Protection Association (NFPA) warning. This is a diamond shaped symbol, divided into four sections, each with a different color.
The red section is for flammability. Is this chemical dangerous to use near heat or open flames?
The yellow section is explosiveness. Will this chemical suddenly react violently?
The white section is for special warnings, such as a W with a line through it signifying this chemical reacts with water.
Each of the first three sections (blue, red, yellow) will contain a number, 0-4. This number tells you how high the risk is for each category, with 0 being the lowest risk and 4 being the highest.
There are also other symbols you may run across. These include:
A test tube with liquid pouring onto a hand = this chemical is highly corrosive. Avoid breathing the fumes or getting this chemical on your skin.
A circle with flames above it = this chemical is an oxidizer. It can ignite flammable materials or otherwise make flames worse if spilled near an open flame.
Skull and crossbones = poisonous, avoid bodily contact.
Wheat with an X through it = hazardous to food, store well away from anything edible.
It is important to understand these different chemical symbols, even if you are striving to live a chemical free existence. You never know what the future will bring. It could very well be that you may need this information in the wake of disaster. If you are bugging out on foot, for example, and come across an abandoned trailer, knowing how to read the hazard symbols on the back can help to keep you safe.