Part One: The Science...
Reducing your scent signature
September 01, 2010
It wasn't that many years ago in the whitetail bowhunting world that the predominant wind direction dictated the locations you could hunt. I used to practice diligent scent control, washing my clothes in non-scent detergent, hanging them outside or storing them in air tight garbage bags, showering with scent free soaps and shampoos, wearing rubber boots, using scent eliminating sprays, putting out scent wicks with fox urine, and even hanging real doe tarsal's in nearby trees in an, "I know this really won't work", attempt at masking my human odor. But no matter what I did there was one consistent result, if a targeted deer came in from downwind, the hunt was over. As soon as I put on my hunting clothes and sat in a tree, human odor became an immediate factor.
I had some awesome locations but couldn't hunt them without the proper wind because there was no doubt I would get busted if the deer came in from the expected direction. There were also excellent locations on ridges, undulations, and in certain terrain features that I literally would never hunt due to swirling and thermal wind currents. In these locations the wind direction could change at any moment and the predominant wind direction meant nothing. One season in particular I didn't even hunt my best location because I never had the right wind direction on the days I was able to hunt.
It is an undeniable fact that the odds of taking a mature buck with a bow are far greater during our short pre rut and rut period leading up to gun season than at any other time of season. Basically we have about 16 days of prime time bowhunting before gun season opens. So, if you have to count on a perfect wind direction in order to hunt your best locations and like me you can only hunt on your days off work, you may not have many if any opportunities to hunt those locations. Thank god, those days are in the past.
There is no question that whitetails rely on their sense of smell for food and survival more than their sense of sight and hearing and their nose is their only sense that needs no other confirmation. When we as hunters can overcome that sense, we can hunt more locations and receive more kill opportunities, it's a pretty basic concept.
|Little in the hunting marketplace was known about activated carbon and its absorptive qualities until Greg Sesselman patented its use in hunting clothing, named it Scent Lok. Photo Courtesy of Scent Lok|
The hunting industry is saturated with products claiming to adsorb and absorb the gaseous and liquid forms of human odor related molecules we emit from bodies. Some claim to kill or eat the bacteria on the human body. Some products claim to mask odors and others claim to suppress odors from escaping through clothing. So what works, and if so, to what extent? Most product claims have some legitimacy, but few take on the entire scope of reducing human odor to the point where deer can't smell them or the odor is so miniscule that the hunter is not seen as an immediate threat.
Scent Free Detergents (hypoallergenic and free of dyes) removes human odor from clothing; aiding in the scent reduction process, however, once that clothing is put on human odor passes through and becomes an issue. If you stop here with your scent free regiment you will get winded.
Every seasoned hunter to aid in reducing human odor uses Scent Free Shampoo, Scent Free Body Wash and Scent Free Anti-Perspirant. Scent Free Wipes can be used once on stand to wipe off your perspiration from overheating during your walk in.
The primary ingredients of many Scent Reduction Sprays for clothing and gear are sodium bicarbonate and water, which for a short period of time will absorb some human related scent-molecules. Some sprays also contain silver (a proven anti-microbial), carbon (a proven adsorptive), or live enzymes (proven to eat bacteria if they do not die in the container), all of which add to the sprays effectiveness at scent reduction. Without question most sprays aid in the scent reduction process.
Note: For 2010 Tink's has partnered with Byotrol in their Vanish scent reduction products of hair & body soap, laundry detergent, odor eliminating spray, and field wipes. Byotrol is a structured combination of existing biocides and other active agents that was developed in the UK for food, medical, and other applications and has been approved by both the Food and Drug Association (FDA) and the Environmental Protection Agency (EPA). For detailed scientific information on how Byotrol is made and works; go to their website at: Byotrol.com and then click on "Rest of the World" then click on "The Science" then click on "Science in Detail"
For those that wear waterproof garments, the use of sprays has little if any effect when used on the exterior of them. Permeability or airflow through most waterproof/breathable garments is so miniscule it is relatively meaningless. Waterproof clothing suppresses (holds in) human odors beneath their Teflon, Polyurethane, or PVC membrane layers allowing the majority of human odor to only escape out the sleeve ends, neck, waist of jacket, zippers, waist of pants, leg openings, and any other venting areas.
There is no question that exterior waterproof clothing has its place for rainy, cold and windy hunting conditions; but its lack of permeability makes it uncomfortable to wear in dry, moderate to warm weather conditions where airflow is required to cut down on and evaporate perspiration.
Bacteria and the odors associated with it comprise only a portion of the human odor we emit and just about every clothing manufacturer makes garments using an inexpensive, chemical Anti-Microbial treatment to kill bacteria and keep it from multiplying. The more a chemically treated anti-microbial garment is washed, the less effective it becomes.
A proven bacteria killer that is more expensive to use and never washes out of the garment is Silver. Our US military uses silver in some undergarments and socks to kill bacteria. Scent Blocker uses weaves of bacteria-phobic silver thread in their S3 Base Layers lineup as does Medalist in their Silver Max series of undergarments, Cabela's uses X-Static (silver fiber) in their MTP series of undergarments, and Browning uses a sliver ion technology in their NTS base layer system.
While there are many companies that chemically treat their exterior garments with an anti-microbial, my research has shown that the most effective bacteria killing garments are those worn against the skin (your bottom layer) because they come in direct contact with the bacteria. An anti-microbial garment worn a couple layers away from the skin doesn't come in direct contact with your bacteria, rendering it relatively ineffective at killing it.
It must be noted that undergarments with only chemical anti-microbial treatments or silver do little to get rid of the odor from the bacteria it kills or the other odors we emit.
The last and most effective scent control item on my list is Activated Carbon and all of Scent Lok's BaseSlayer undergarments have a chemical anti-microbial treatment to kill bacteria and activated carbon to adsorb odor molecules.
The American College Dictionary defines adsorb as: "to gather (a gas, liquid, or dissolved substance) on a surface in a condensed layer, as when charcoal adsorbs (sucks in) gases".
Webster's Dictionary defines adsorb as: "A process by which molecules are taken up on the surface of a solid by chemical or physical action. Large amounts of gases, for example, may be adsorbed on the surfaces of a porous material such as charcoal".
Those are two definitions from two leading dictionaries that sum up the adsorptive or bonding qualities of activated carbon or charcoal.
Activated carbon is one of if not the most adsorptive substance known to man. It is produced from carbonaceous materials like nutshells, wood and coal. Carbons are complex materials that are difficult to classify on the basis of their behavior, surface characteristics and preparation methods. However, some broad classifications are made for general purposes based on their physical characteristics.
The hunting clothing industry uses large granular activated carbon as opposed to powdered carbon. Granular carbon is preferred for all adsorption of gases and vapors as their rate of diffusion are faster. Carbon granule sizes are classified by the U.S. Standard Mesh size number of sieve they can pass through.
Activated carbon is a form of carbon that has been processed to make it extremely porous and have a very large surface area for adsorption or chemical reactions. Due to its high degree of microporosity, the surface areas of the primary, secondary, and tertiary pores along with the exterior surface area of just one gram of activated carbon has a surface area of approximately 2.17 tennis courts.
It is common knowledge that activated carbon and charcoal is used by multitudes of manufacturers for water purification, and air and exhaust filtration purposes. Ours and most other militaries in the world use activated carbon suits when dealing with potential chemical warfare to keep deadly chemical molecules from penetrating the garment and reaching the soldier's skin.
Little in the hunting marketplace was known about activated carbon and its adsorptive qualities until Greg Sesselman patented its use in hunting clothing, named it Scent Lok, and introduced the technology into hunting marketplace. It took the company several years to gain acceptance. Think about it, how could any seasoned hunter even conceive fooling a downwind whitetails nose, I know I struggled to comprehend it. However, after listening to a few testimonials from average Joe hunters that weren't getting paid to endorse it, I bought one.
Having bowhunted since 1964 I have witnessed dramatic advancements to bows, sights, rests, arrows, broadheads and clothing, however, other than the compound bow there has been no technology advancement more significant to the taking of animals that rely on their nose for survival than a properly cared for activated carbon lined suit.
Of course, there will continue to be millions of deer taken by the old "I just hunt the wind" concept. But lets be perfectly honest here, there is absolutely no way, I don't care how good you think you are, that anyone can predict exactly which way a buck is going to come in from during the rut phases when pursuing estrous does on unpredictable routes. While "Just hunt the wind" worked best during its time, it doesn't cut it for me anymore.
Activated Carbon Work?
We are constantly emitting many types of gaseous and liquid molecules associated with human body odor in addition to the odor from our bacteria. As molecules pass by the layer of carbon they are attracted to and bond to it. The scientific name for this physical adsorption is "VanDerwaals bond".
Any manufacturers clothing with a Scent Lok branded green liner has enough activated coconut carbon to absorb approximately 40 hours (hunting time) of molecular bonding before the saturation level of the carbon is high enough that reactivation is required. While Scent Blocker is a licensee of Scent Lok, and use a different type of carbon, their exterior suits also perform in much the same manner.
It is important to understand that the molecular bonding or saturation process is taking place from the moment the clothing is removed from an airtight container. Unfortunately carbon can't be programmed so that the scientific VanDerwaals bonding process works only on human odor related molecules and as soon as it is exposed to outside elements other molecules bond to it and saturate it as well. That is exactly why carbon clothing should be stored in an airtight container when not in use.
There is no way we as consumers can tell (other than getting winded) when the saturation point has been reached and a suit requires reactivation. Personally I react my suits about every three hunts, or twice as frequently as recommended.
Reactivation is obtained by putting the clothing in a clean (no scented dryer sheet odors) household clothes dryer for 30 to 40 minutes on the highest heat setting available, or as the care instruction label advises. The heat from the dryer creates molecular energy or motion, allowing a percentage of the molecules to break free from the carbon and exit out the dryer vent. The reactivation process doesn't totally reactivate the carbon but frees up enough space in the pores and on the carbons surface for continued use.
Scent Lok doesn't profess 100% reactivation and that is why with average use and proper care their clothing has about a 5 to 8-year lifespan before the carbon reaches a molecular bonding saturation point and the suit loses its effectiveness.
There is and always will be armchair quarterbacks and conspiracy theorists no matter what the science or issues may be. To some, 9-11, Pearl Harbor and the Kennedy assassination were all inside jobs. In this case they simply can't grasp how carbon technology works in conjunction with hunting clothing. It is not the case that just because some data cites that temperatures exceeding 1,000 degrees are required for energetic movement of specific types of molecules or for complete, industrial level reactivation, that a lower temperature will be completely ineffective at partially reactivating carbon enough for hunting purposes.
Just as there are many types of dogs, cats, fish, birds, horses, etc., and each type has its own characteristics and size, there are many types of molecules with each having its own characteristics and size. Molecular size and characteristics dictate the size of carbon pores they may enter, how they physically bond, and the amount of heat required to make them more energetic, react or expand, and physically break that bond from the carbon. A logical example that we can relate to concerning size is that a Miniature Terrier can go down a rabbit hole yet a Great Dane can't; yet they are both dogs.
Example: Low heat levels creating molecular energy or expansion can be witnessed in our everyday lives. There are expansion joints in steel bridges and concrete highways because the molecular energy of the steel and concrete molecules created by warm weather conditions cause them to expand. Without expansion joints expanding steel will bend and expanding concrete will buckle, destroying the bridges and highways on sunny, 80-plus degree days.
Another example of how heat affects molecular energy is with water. Let's suppose you have a pan of water. If you leave the pan out at room temperature the water will eventually evaporate. However if you put the pan on the stove on simmer it will evaporate faster, if you turn the heat up and allow the water to boil it will evaporate even faster. Just as temperature effects the evaporation time of the water into the air, it affects the release of gas molecules from carbon.
It must be noted that for hunting related purposes reactivation is not an all or none proposition! The question isn't whether the carbon is completely regenerated but whether enough reactivation has occurred to adsorb and aid in eliminating scent for more hunts.
Do not assume an activated carbon-lined suit is a magic bullet, because it is not. They require very specific care and when not properly cared for and used in conjunction with scent free rubber boots and a scent free backpack, you better play the wind.
It is impossible to totally eliminate human odor, but with a complete scent control system a hunter's scent signature can be reduced to such a low level that deer do not consider them an immediate or close enough threat.
Next month -- Part 2.
To enrich your bowhunting skills John Eberhart produced a 3 volume instructional DVD series titled "Bowhunting Pressured Whitetails" and an instructional archery DVD titled "Archery Mechanics" and co-authored with his son Chris the books "Bowhunting Pressured Whitetails" and "Precision Bowhunting". They are available at: www.deer-john.net or www.eberhartsbowhunting.com