Anatomy of a MSDS: Sections IX-XII


What lies beneath is danger if you don’t know the risks associated with the physical and chemical properties of a product. A MSDS will provide closer inspection.

A Material Safety Data Sheet (MSDS) accompanies many items, including Dow Corning’s DC4 Electrical Insulating Compound. We have been using this product throughout in order to deconstruct the layout and sections normally found within this type of document. Part Three of “Anatomy of a MSDS Sheet” will explore Sections IX-XII. Let’s dive into it.

Section IX: Physical And Chemical Properties

As the heading indicates, this section reveals a list of physical properties as well as chemical properties the product contains. DC4 is a grease with a translucent white hue that emits a mild odor.

Section IX also repeats information found originally in Section V, i.e. the flash point, autoignition temperature, and flammability limits in air.

In addition, there are nine chemical properties listed in DC4’s MSDS, most of which are deemed “Not determined.” Many are self-explanatory: Freezing/Melting/Boiling points as well as viscosity, vapor density, solubility in water and pH.

“Specific gravity” is a reference to the ratio of a compound’s density as compared to another. Since water has a specific gravity equal to one, it is most often used as the reference point (at least when comparing liquids; gases get compared with air). For DC4, the specific gravity is greater than (>) 1, so it is denser than water. The “@25°C” is used because that is the upper limit value that falls within room temperature range.



As you can see the “Vapor Pressure” at room temperature (25°C) is not determined; this term is important if you want to know a product’s evaporation rate as well as its volatility. The more volatility, the higher vapor pressure it possesses. Speaking of which, DC4 has no known volatile content, i.e. ingredients that rapidly evaporate or tend to explode violently (at least not of this writing).

Knowing these properties not only leads to safer use but also to better and smarter applications of the product.

Section X: Stability And Reactivity

Based on the previous section’s claim that DC4 is not volatile, Section X verifies this by stating the product is chemically stable. However, DC4 should not be placed near any oxidizing material, otherwise the combustion of the product may result; this is found in the “Materials to Avoid” sub-section. Fortunately, there are no other conditions to avoid.



A somewhat confusing sub-section is “Hazardous Polymerization,” known also as autoacceleration. What is that? Don’t worry, we were confused at first, too. Polymerization occurs when individual molecules (monomers) react to form a chain (polymer). If this process occurs at a fast rate, that’s when it becomes dangerous. Polymerization involves the release of heat and if that escalates too fast, a fire or explosion may result.

Finally, the sub-section “Hazardous Decomposition Products” warns that high heat may lead to thermal breakdown. During this decomposition, “carbon oxides and traces of incompletely burned carbon compounds,” silicone dioxide, and formaldehyde may evolve. Knowing the by-products from such an event allows you to take the proper precautions when disposing of it.

Section XI: Toxicological Information



What a bummer. DC4’s Section XI is pretty much empty, except with a statement saying that no information regarding the subject is known. That’s all right. We can still enlighten you.

Toxicology of course deals with poison. Thus, anything relating to the nature of poison, including its harmful effects and subsequent treatment once exposed, would be included here.

A good example of this section can be found in the MSDS for Mobilgrease 28. In this MSDS, you will see this section broken into two general parts, “Acute Toxicity” and “Chronic/Other Effects,” i.e. short-term and long-term effects.

Acute toxicity is presented in a convenient chart. The chart’s left column, ‘Route of Exposure’ shows the area in which the product can affect your body, e.g. breathing it, eating it, or getting it in your eye or on your skin. A particularly puzzling aspect of this column is the use of LC50 and LD50. What do they mean? LC stands for “Lethal Concentration” and the 50 refers to the fact that half (50%) of the tested animals were killed. LD stands for “Lethal Dose” and the 50 refers to the same as above. Since humans cannot be tested on, groups of animals must be exposed to concentrated levels of the product either in the air or in water. The right-hand column ‘Conclusion/Remark’ simply states the degree of toxicity based on how the lab animals were exposed to the product.

As for chronic effects, Mobil Grease 28 contains ingredients (synthetic base oils and Phenyl-alpha-napthylamine) that have not been deemed significantly harmful based on laboratory studies. Of course that is assuming you are using the product as normally intended.

Section XII: Ecological Information



Up to this point, most MSDS sections have discussed how the product affects you, the end-user. Section XII instead places the focus on the environmental impact a product possesses. For DC4, “Environmental Fate and Distribution,” “Environmental Effects,” and “Fate and Effects in Waste Water Treatment Plants,” are all followed by the statement “Complete information is not yet available.” This may be because not enough studies have been conducted and tests have not been run and analyzed with any certainty. However, if DC4 did lead to adverse effects on ecosystems, Dow Corning would not hesitate to transfer that knowledge to users.

Still, this section has an “Ecotoxicity Classification Criteria” table underneath the aforesaid sub-sections. That way if there are measured levels of toxicity from the product, you can use this table as a basis for comparison. In relation to the previous section, ecotoxicity has LC, but you will notice it also has EC; this stands for “effective concentration” and indicates toxicity as it relates to the environment. The table uses criteria considered low, medium, and high hazard. Directly below each parameter is the numerical value for aquatic and terrestrial levels of ecotoxicity. This table is derived from the American Society for Testing and Materials (ASTM) and their guidelines for “Environmental Toxicology and Risk Assessment.”

There you go. The finish line is within reach. Come back for Part Four as we conclude the “Anatomy of a MSDS” blog post series. As always, stay safe out there…

***UPDATE*** Read other parts in the “ANATOMY OF A MSDS” blog post series

Part One – Sections I-IV
Part Two – Sections V-VIII
Part Four – Sections XIII-XVI

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About Otto the Owner
Otto the Owner

I'm Otto. Friends call me Otto. As an avid owner of aircraft I know the costs and benefits of flying. I've had enough experience with planes to grow rust on my mustache. While I'm not the best at words, my buddy Skylar helps me write these posts so I can transfer any knowledge onto other aviators out there.