Caution: Some states and many political subdivisions restrict the sale, possession and use of defensive sprays. Make sure you consult your local laws.
Pepper spray is a very useful tool that can add tremendous flexibility to one’s defensive response. Thus, proper training and mental preparation are essential.
I suppose it is bad form to start an article with a discussion of what it is NOT about, but humor me anyway.
This article will not examine whether you should carry pepper spray as a supplement to a defensive handgun; that requires a careful assessment of your personal needs and circumstances. But I would urge you not to make the decision without proper reflection. Pepper spray is a very useful tool that can add tremendous flexibility to one’s defensive response, but it also adds complexity because it requires you to choose between options in the stressful instant of a violent encounter. Thus, proper training and mental preparation are essential.
Even though we have other factors to consider, it is still interesting to look at the hotness of some commonly available sprays. The table at the end of this article lists some manufacturers’ values for hotness and OC content.
But, if you are considering it, then hotness is definitely one important factor in the selection of a suitable spray. There is considerable evidence from law enforcement experience that (everything else being equal) a truly hotter spray (within reason) is more likely to bring an effective end to hostilities. Did that statement strike you as vague and wishy-washy? It was supposed to!
As we will see, the statements “everything else being equal,” “a truly hotter spray,” and “within reason” are important qualifications that will form the basis for much of our discussion. In other words, there’s more to hotness than meets the eye. Just as importantly, effectiveness is not determined by hotness alone; a follow-up article on the Concealed Carry website will examine many other important factors. (See //members/1295.cfm)
Pepper Spray Hotness is a Bit Complicated
At first blush, you wouldn’t think that hotness should be too complicated because it boils down to the concentration of the active ingredients in the spray; we are all familiar with everyday situations where concentration is important. Everything from spices in your favorite foods to the antifreeze in your car’s radiator is critically dependant on the right concentration. Too little–or too much– and you will not get the desired effect. But there is a complication when it comes to pepper sprays: they contain a hot pepper extract called oleoresin capsicum or OC, but the OC itself is not the actual active ingredient. Rather, the OC contains specific chemical compounds called capsaicinoids and these actually produce the desired effects.
This may strike you as scientific hairsplitting, but it is extremely important to understand because the capsaicinoid content of OC can vary dramatically from one extract to another. As a result, a higher “percentage OC” does not necessarily mean a hotter spray! This is critical to know because certain products tout a high OC concentration as a huge selling point, with some proclaiming 12, 13, 15–even 17 or 18 percent OC. But by themselves, such numbers are meaningless.
This is a tricky concept, so here’s a way to visualize it: imagine you have two stacks of money that each contain a mixture of real and counterfeit bills. The real bills represent the OC (pepper extract) in the spray and the counterfeit ones represent the inert “vehicle” or “carrier” that makes up the balance of the liquid in the can.
The number of actual dollars in each stack represents the actual active ingredients (capsaicinoid molecules) that are present. Let’s say that the first stack of money contains two authentic $50 bills and eight fakes, while the second contains four real $10 bills and six fakes. Note that the second stack has a higher percentage of real bills (4 out of 10 = 40% vs. 2 out of 10 = 20%), but it is the first stack that actually contains more real dollars (two $50 bills = $100 vs. four $10 bills = $40.)
In the end, a lower concentration of bigger bills leads to more actual dollars. The same thing applies with pepper sprays; a lower percentage of an OC extract that is richer in capsaicinoids can lead to a hotter spray.
Is the Spray as Hot as Claimed?
There’s another related concern. Even OC extracts from the same source can vary in capsaicinoid content from batch to batch due to differences in pepper growing conditions, extraction techniques, and other variables. Unless some means of analysis is used to keep track of this, the hotness of a given pepper spray can also vary from batch to batch!
Hotness was traditionally measured in the spice industry by taste testing, but it can also be measured by more objective methods of chemical analysis. Security Equipment Corporation, maker of the “Sabre” brand of sprays, made a very valid point by commissioning an independent laboratory to chemically analyze commercially available pepper sprays. Some were found to be considerably “less hot” than claimed.
This gets us to another extremely important point. Self-defense sprays are not regulated by the Federal government, (at least with respect to contents and effectiveness) so there is little to restrict a seller from making outlandish claims about hotness. To cite one example, I found a product in a local store that–if its claims are true–would calculate out to be about three times hotter than the hottest sprays commonly used by law enforcement!
But an executive from a reputable manufacturer told me that these products are almost invariably not as hot as claimed. In fact, they may even be considerably cooler than products which accurately cite a lower degree of hotness. As a practical matter, the biggest concern here is winding up with a product that is far less effective than you were led to believe. The best bet is to seek products from a reputable manufacturer that has been in business for a while and that can cite a satisfied law enforcement clientele.
Let’s Look at the Numbers
Let us now assume that we are working with accurate hotness values. We still have the problem of understanding them, so let’s look at an example: the hotness of OC is often rated using the Scoville Heat Unit (SHU) and we need to consider both the hotness of the OC and the concentration of OC in the spray to assess the hotness of the spray itself. Once you see how it works, it’s actually fairly straightforward.
For instance, if a spray uses an OC extract with a hotness of 500,000 SHU at a concentration of 10%, then the calculated spray hotness would be 50,000 SHU, which is simply 10% of the hotness of the OC itself. In the same way, a 2,000,000 (2 million) SHU OC used at a 5% concentration will yield a spray hotness of 100,000 SHU (which is 5% of 2 million SHU).
Note the interesting result: the spray containing 5% OC is actually twice as hot as the one that contains 10% OC (100,000 SHU vs. 50,000 SHU). To put it simply, even though the hotter OC is used at only half the concentration, it is also four times as hot. The net effect is that the spray with the lower percentage OC is twice as hot.
Because SHU ratings are cumbersome, some manufacturers express their sprays in terms of capsaicinoid content. But this can actually make the confusion worse because we now have a second way of measuring the same thing! Capsaicin (note that I did not say capsaicinoid) is a specific chemical compound, and it has a hotness of 15,000,000 (15 million) SHU in its pure form. We can thus say that a pepper spray with a spray hotness of 50,000 SHU is equivalent to 0.33 percent capsaicin in terms of hotness, simply because the spray hotness (50,000 SHU) is 0.33 percent of the hotness of pure capsaicin (15 million).
A spray with a hotness of 100,000 SHU would be equivalent to 0.66 percent capsaicin because 100,000 is 0.66% of 15 million. But capsaicin is only one member of the heat-producing capsaicinoid family of chemical compounds and real-world OC extracts contain a mixture of capsaicin and other capsaicinoids. Because they are not all equally “hot,” the “percent capsaicinoids” determined by chemical analysis is not the same as the “capsaicin equivalent hotness” that we just calculated.
However, some manufacturers effectively use the values interchangeably when calculating the hotness of their products. As a practical matter, the difference is not one to lose sleep over; the far bigger concern is whether the numbers on the dispenser accurately reflect the contents.
Real-World Hotness Values
Now that we understand the numbers, we can talk sensibly about appropriate hotness levels. Several companies offer sprays based on a 10 percent concentration of 500,000 SHU OC (spray hotness of 50,000 SHU or 0.33% capsaicin equivalent.) These were, and still are, widely used by law enforcement.
But many agencies have moved to hotter sprays that run in the range of 100,000 to 200,000 SHU (0.66 to 1.33 percent capsaicin equivalent). It’s difficult to objectively assess the exact real-world relationship between hotness and effectiveness because there are a lot of other variables involved. In contrast with things like handgun ammo, it is possible to test pepper sprays on volunteers, but this is not perfect either. Perhaps most importantly, volunteers are generally not stoned, drunk, enraged, or totally off their rockers–and these are certainly important variables in real life!
These problems notwithstanding, the general consensus seems to be that the mid- to high-hotness products are notably more effective than the ones at the bottom of the range mentioned previously. It should be noted that it is possible for pepper sprays to be too hot.
Even though defensive sprays are largely unregulated, (at least at the Federal level) the Environmental Protection Agency does regulate animal repellents like “bear spray.” The EPA has set a maximum limit of 2 percent capsaicinoids (roughly a 300,000 SHU spray hotness) to avoid eye damage and other hazards. Whether the EPA is more worried about the user or the grizzly bear is an interesting question. But either way, this certainly establishes a safety and liability benchmark that reputable manufacturers will not exceed. Fortunately, hotness (especially beyond a certain point) is by no means the ONLY factor that governs the effectiveness of pepper spray. We will examine many of the other critical factors in the follow-up article on the USCCA Website.
Even though we have other factors to consider, it is still interesting to look at the hotness of some commonly available sprays. The table at the end of this article lists some manufacturers’ values for hotness and OC content. The three columns on the right pertain to spray hotness, and they all tell us the same thing, just in different units.
The rightmost column states hotness in relative terms, assigning the once-dominant 10% / 500,000 SHU OC formulations a relative hotness of 1.0. Thus, a spray with a value of 2.0 can be regarded as roughly twice as hot as this reference formulation, and so forth. Please note that this table is intended only to illustrate a representative sampling of sprays, so the absence of a particular brand should not be automatically regarded as a condemnation.
[ Tim Thorstenson is a chemist by education. He welcomes feedback, and you can reach him at email@example.com. ]
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