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What are Class 8 Corrosive Materials?

March 8, 2023

Although it’s important to label, store, transport, and dispose of any kind of hazardous waste correctly, Class 8 corrosive substances require extra attention to detail. This blog entry explains exactly why. Q&As include:

1. What are Class 8 corrosive materials?

2. What are acids and bases?

3. How do acids differ from bases?

4. What is an oxidizer and its oxidizing potential?

5. What are some examples of Class 8 corrosives?

6. How do you store Class 8 corrosives?

7. How do you transport Class 8 corrosives?

8. Where can you get local help managing Class 8 corrosive materials?

1. What are Class 8 Corrosive Materials?

Per the EPA, Class 8 corrosive materials are liquids or solids that cause full-thickness destruction of human skin at the site of contact within a specified period of time (see source). As such, they’re understandably of particular interest to both the EPA and the federal DOT, not to mention your state and local authorities. Appreciating how and why Class 8 corrosive materials are such bad actors requires some understanding of acids vs. bases (see Q.2).

2. What are acids and bases?

Liquids and solids that are deemed Class 8 corrosives are either acids or bases. Something is considered an acid or a base dependent on its pH level, where “pH” stands for “potential hydrogen” (see source). (Some people say it’s “power hydrogen.” Those with a flair for Latin prefer pondus hydrogenii, which, if you believe everything Google tells you, translates to “weight hydrogen.”)  Anyway…

3. How do acids differ from bases?

In effect, they don’t. They’re both corrosives.. But acids give up hydrogen protons while bases receive them. And the movement of hydrogen in such a manner—in one direction or the other—is highly corrosive. I.e., it burns. 

The reference point for calling something an acid vs. a base is pure water, which has a pH = 7, meaning that the “H” protons in your H2O don’t migrate in one direction or the other to cause corrosive mischief. A substance with a pH level less than 7 is called an acid. Higher, and then it’s called a base.

(N.B. While acids are predictably called “acidic,” bases are less intuitively known as “alkaline.”)

As you might guess, the more acidic or alkaline a substance, the more corrosive it will be. But less obviously, the numbers aren’t linear. (You might say this is “exponentially” important to understand.) 


  • Remembering that a lower number means relatively more acidity, a pH = 4 is ten times more acidic than pH = 5, and 100 times more acidic than pH = 6.  

  • Similarly, remembering that a higher number is relatively more alkaline, a pH = 13 is ten times more alkaline than pH = 12, and 100 times more alkaline than pH = 11 (see source).

4. What is an oxidizer and its oxidizing potential?

We knew you were going to ask that. 

Next time you have a Coke®, you might ponder that most commercial lemonades and sodas have a pH of about 2.5, not too far (thinking linearly for a moment) from hydrochloric acid (pH = 1.1 @ .380 concentration) (see source). 

To understand why imbibing one is okay while the other is definitely contraindicated as a mixer, consider that in addition to pH, acids also have something called “oxidizing potential.” This is their relative ability to strip electrons. The ingredients in soft drinks—while very acidic—nonetheless have little oxidizing potential. So, drink up.

(We might mention here that at 4.0, beer is significantly less acidic than soda. Draw your own conclusions.)

5. What are some examples of Class 8 corrosives?

There are many kinds of Class 8 corrosives. Herein we list three common acids and three common bases, each in typical consumer/industrial concentrations:


  • Hydrochloric acid (HCl) (pH = 1.1 @ .380 concentration) is used in water and salt purification, as well as making batteries, fireworks, leather, and building materials. Your digestive system also produces HCL, sometimes to spectacular effect. See heartburn.

  • Sulfuric acid (H2SO4) (pH = 0.5 @ .335 concentration) is used to produce dyes, paints, pigments, explosives, and most famously: fertilizers and lead-acid batteries. This stuff is truly wicked, uncontrollably boiling and bubbling when it accidentally comes into contact with plain old water.  

  • Nitric acid (HNO3) (pH = 1.2 @ .680 concentration) has many of the same uses as H2SO4. In some cases, people use it to remove warts, although we counsel extreme caution when doing so, since it can also dissolve most metals. And mixed with HCl, it forms a fuming liquid used to dissolve gold and platinum—should the need arise.


  • Ammonium hydroxide (NH4OH) (pH = 10.52 @ 1mM concentration) is used as a refrigerant, as well as for manufacturing detergents, textiles, soaps, ceramics, pharmaceuticals, inks, and explosives. It’s also used to clean glass—and added to food to control acidity.

  • Potassium hydroxide (KOH) (pH = 10.98 @ 1mM concentration) shows up in the production of fertilizers, biodiesels, and soft soaps. Chemists use it as an electrolyte (in electrochemistry, of course) and in a process commonly called “chemical cremation” (which we don’t even want to think about—and is illegal in 30 states anyway.)

  • Sodium hypochlorite (NaClO) (pH = 11 @ .05 concentration) is used in waste management, food production, and as a bleach or disinfectant. It’s also a pesticide.

6. How do you store Class 8 corrosives?

Very carefully. Violent reactions between incompatible acids and bases can cause fires and explosions, as well as produce toxic and/or corrosive gasses.

Storing Class 8 corrosives require specialized cabinetry that—depending on your location—might include such features as self-closing doors that are close-fit, cannot swing inward, are “escapable” from the inside, and secured by at least two catches.

Other requirements might be the cabinet’s construction of corrosive-resistant material or, at least, protection by a corrosion-resistant lining or coating. Shelves should be perforated to accommodate airflow. 

The cabinet’s base should form a liquid-tight sump—and probably be large enough to hold a specified percentage of its total capacity, should the worst happen. Oh…and blue. By convention—although not by law—cabinets designed for Class-8 corrosives are blue.  

Obviously then, that second-hand IKEA wardrobe you found on Craig’s List isn’t going to pass muster. You should get expert advice.

7. How do you transport Class 8 corrosives?

You just can’t throw a Class 8 corrosive into the back of your Silverado and haul it down to the dump. The dump won’t take it, and your Silverado might dissolve before you get there.  

Instead, you need to hone how you classify the material by assigning it into one of three (actually four) packing groups that regulators stratify according to the relative severity of the hazard it poses. These are:

  • Packing Group I causes full thickness destruction of intact skin tissue within 60 minutes of 3-minute exposure or less.

  • Packing Group II causes full thickness destruction of intact skin tissue within 14 days after 3 to 60 minutes of exposure.

  • Packing Group III # 1 causes full thickness destruction of intact skin tissue within 14 days after 1-to-4 hours of exposure. 

  • Packing Group III # 2 doesn’t cause full thickness destruction of intact skin tissue but corrodes steel or aluminum faster than 0.25 inches yearly (at a test temperature of 130°F). 

Other shipping requirements include:

  • Shipping manifest. The hazardous waste manifest is an EPA-required form-filling exercise completed by you. It indelibly attaches a hazardous waste to your enterprise as it migrates from your site to the hazardous waste management facility that will ultimately process it—along with all the legal, financial, and social liabilities that are endemic to hazardous material removal.

  • Labeling. Hazardous waste labels are always diamond-shaped, and their size must adhere to international standards, measuring at least 4″ x 4″ (100 mm) on each side, square-on-point. The Class 8 variety graphically features liquids spilling from two glass vessels, respectively doing damage to a hunk of metal and someone’s hand. 

  • State-specific requirements. E.g., California (surprise!) has its own special requirements that include but aren’t limited to (1) the composition and physical state of the waste, (2) a statement calling attention to its hazardous properties, (3) the generator’s name and address.

8. Where can you get local help managing Class 8 corrosive materials?

Anything harboring the ghoulish potential to cause “full-thickness destruction of human skin” requires safe and legal hazardous waste management.

Don’t take chances. 

Secure properly licensed and experienced hazardous waste management experts to ensure that all consumer and commercial corrosives are properly stored, segregated, transported, and ultimately disposed of compliantly with federal, state, and local standards. 

The legal, financial, and reputational liabilities of not doing so are formidable.

Contact us today.

Disposal of hazardous waste doesn’t have to be painful.