Offensive odors have plagued mankind across all of human history. They were more or less tolerated as an inescapable evil until about 200 years ago, when sewage systems, garbage collection and other control measures were institutionalized. In the U.S., as late as 1914, there were still more privies than toilets and the burning of incense was commonplace. Hand-held atomizers were used to disperse low cost perfumes into the air. Heavily scented salt, mothballs or soap cakes were used in public bathrooms and are still in use today.
However, due to the resurgence of lightly fragranced air fresheners and the demand by today’s educated consumer, the method of “covering up” is simply not a desire control method anymore. This was the cause for the tremendous resurgence of “true odorless neutralization” for all industries and what inspired the chemists at Alpha Aromatics to originate Metazene®; a counteractant that has become the most effective molecular odor neutralizer in the marketplace today.
While creating magnificent scents is our speciality, eliminating malodors is just as much of an art form. But how exactly does Metazene work, and what makes it dominantly more effective than other odor neutralizers out there? This article delves into the history of air fresheners, a number of industrial methods for controlling airborne odors, the secret behind Metazene’s powerful effect on every type of malodors and its multitude of commercial applications.
Aerosol Air Freshener History
The aerosol-packaging mode was invented by Rotheim in Norway during 1931, but wasn’t used commercially until 1947. Almost immediately after that, aerosol air fresheners were catapulted into the second largest product category (after insecticides), since chemists had discovered that the unprecedented degree of break-up produced such tiny particles that virtually all the fragrance power was unleashed within a few seconds. Most particles were well below 0.001 inch in diameter as dispensed. They rapidly got still smaller as solvents and dilutents evaporated, leaving tiny microdroplets of almost pure fragrance that could remain suspended in the air for very long periods.
By 1949 at least 20 firms were actively selling aerosol air fresheners, and the race was on to develop still better formulations. The perfumes did little or nothing to control malodor; they merely covered them up, to a degree. In other words, they were reodorants, not deodorants. The industry needed something more. It needed an ingredient that would cancel unwanted odors by various physicochemical means, yet not react with any pleasing odors that the product might leave in their place.
After a lot of fruitless experimentation with odor masks, odor control agents, aldehydes, sulfonates and unspecified materials, Metazene® was discovered, and found to function as a odor-counteractant without anesthetizing the nose.
It was able to form a coordinate bond with a variety of osmophoric, or odorproducing sites that are unique to malodorous molecules, such as aminoand thiol (mercapto-) moieties. The Metazene molecules actually surrounded these sites, clustering about them as polymeric bonds developed, and also changing their electron configurations. As a result, odor was dramatically reduced — often eliminated altogether.
The anhydrous aerosol air fresheners that were in use until about 1962 (and to a limited extent up to the present time), produced sprays where the particle size was mainly from about 20 to 30 microns (0.0007 to 0.0012 inch) in diameter. This small size was important for two reasons. Since a typical 25-micron (0.001 inch) particle with a density of 1.00 g/ml settles in tranquil air at only about 2.01 cm/sec (3.9 ft/min), most of the released material was able to remain in the air for over 60 seconds.
If the formula contained Metazene, then the odor counteractant generally had a minute or more to contact and destroy those offensive odors that might be present.
The second advantage lay in the large number of particles released every second. If all the particles were 25 microns (0.001 inch) in diameter, the number would be 121,000,000 per ml, or about 100,000,00 per second. Actually, there are so many almost invisible particles in the 5 to 25 micron range, that the true number exceeds a billion per second. Given this huge number of particles, the likelihood of impaction with odor molecules is enhanced. The situation can be likened to that of a person shooting into an oak tree loaded with acorns — more acorns will be struck by the many small pellets from a shotgun than by the single bullet from a rifle.
Around 1960, with so many marketers now offering aerosol air fresheners in a market of about 105 million units and one which was beginning to be fragmented by the disinfectant/deodorant sprays, timed-release products and sachet sprays piece inevitable became of extreme importance. Many marketers began to weigh the option of deleting the typical 2.5 percent or so of Metazene and adding another 0.50 percent to 1.00 percent of fragrance, perhaps with the idea of drowning out the offensive odors in a flood of scent. A few opted to take this less sophisticated approach.
Also, it was once thought that combining Metazene with other so-called odor neutralizers was more actively effective, but this has been proven false and was just merely a means of price reduction. Sample efficacy demonstrations with increased Metazene content outweigh all the odds. However, where desired, an alternative compound known as “Metzazene-MLM” was developed as a cost-saving alternative for those who utilize the blended method.
In 1961, S.C. Johnson & Sons, Inc. launched a line of reformulated Glade air fresheners that transformed the industry. The new products were water-based. They typically contained about 65 percent water and 30 percent isobutene propellant, and this acted to remove about 11 cents from the formula cost of a typical six-ounce can. As a matter of survival, the rest of the industry struggled to reformulate their products. The only ones of the industry that were immune to this crisis were those higher priced air fresheners marketed to “niche” specialty industries. They viewed the water-based products as inferior, producing coarse, loud, wet sprays that could spot polished furniture, and which also forced the consumer to also spray non-ionic emulsifiers and corrosion inhibitors into the air.
Water is composed of molecules firmly associated together through hydrogen bonding forces, and it is thus very hard to break up into a fine mist. Also, the breakup efficiency that is possible for single-phase (soluble) aerosol systems is not achieved by two-phase (emulsified) formulations. These facts explain the relative coarseness of the water-based air fresheners, which typically emit particles in the 40 to 60 micron (0.0020 to 0.0024 inch) range. The typical 50-micron particle drifts downward at the rate of 7.8 cm/sec (15.0 ft/min). This can be quickly shown by holding one’s hand, palm up, about five feet from the “water-base” aerosol can and about a foot or two from the axis of the spray. A few seconds after actuation, a sensation of wetness/coolness can be felt on the skin.
The typical 50 micron water-based particle is also 8.00 times more massive than the 25 micron anhydrous air freshener particle, assuming they have the same density, so it follows that the aerosol will emit only 12.5 percent as many as these larger particles, per second of spray time.
These concepts would suggest that water-base air fresheners can be only about 3.3 percent as effective as the anhydrous types, in both odor counteraction and “reodorization”; but this isn’t true. In actuality, both the Metazene and fragrance ingredients partition themselves between the water emulsion phase and the hydrocarbon propellant phase. The amounts in each will vary according to the emulsifier that is used, but a substantial percentage will remain in the propellant in any event.
Metazene is soluble in isobutane and propane in all proportions, yet is almost insoluble in pure water without the use of nonionic surfactant such as Triton X-114 or Igepal CA-620. Experiments in which the liquid propellant phase is isolated and allowed to slowly boil off, leaving a residue, have proved the preponderance of Metazene partitions into the hydrocarbon layer. This is important, because it explains why Metazene works so well in water-based, emulsion type formulas.
As the product discharges, micro-droplets of water-phase in continuous phase of liquid propellant pass through the aerosol valve and into the air, and in a matter of microseconds, the liquid propellant bursts into a gas, leaving Metazene and any perfume in the air as extremely fine droplets. The droplets are so small that they are able to float about in the air for about six minutes to an hour or more, and this makes them extremely effective.
Tests have been made, adding typically 2.50 percent and 5.00 percent Metazene to water-based, emulsion type air fresheners, both with and without fragrance. Odor-counteractancy and fragrance bloom were compared with a placebo formulation containing 2.50 or 5.00 parts Metazene in 30.00 parts of Propellant A-46 (14 percent propane and 84 percent iso-butane). Valve delivery rates were adjusted to make the emission of Metazene fairly constant between the regular and placebo formulations.
The malodorant tested was skatole, formed by the action of bacteria on albumen, fish and many other substances. It has an overpowering fecal odor and is a major contributor to noxious odor problems present in bathrooms. In pre- liminary experiments, the Metazene in Propellant A-46 gave the best control, fol- lowed by the 5.00 percent Metazene water-based air freshener. The mal-odorant was instantly transformed into an acceptable state reduced to something resembling hot, stale candle wax. The light fragrance was useful in “freshening” the remaining residual odor.
Metazene, delivered from the placebo, seemed to be roughly two to four times as effective against skatole than that from the waterbased formulas. The reasons must be speculative. They could include some emulsification of the odor counteractant in the microdroplets of water, either as original content or rainout impaction. Water might also make the Metazene temporarily less chemically reactive; however, the highly effective 10 percent Metazene formulation was not tested at that time.
“Prescription Series” Treatment” TM compatible deodorizing fragrances have been proven effective in conjunction with the Metazene content to effectively and economically control specific household, institutional and industrial malodorous situations.
Industrial Applications For Controlling Airborne Odors
The main attraction of Metazene is its ability to control existing airborne odors. To varying extents, depending upon application, it may also provide control of nascent or newly created objectionable odors. In parts, this is due to its extremely low vapor pressure of about 0.005 mm at 25oC (77oF), which, for purposes of comparison, is only slightly higher than glycerin. Odor molecules that strike active Metazene films are either mitigated or cancelled through Hydrogen-bonding, adsorption and encapsulation. The addition of very small amounts of Metazene® to solutions that have offensive odors will generally have the same beneficial effect.
Metazene is best known for its ability to counteract airborne malodors in a variety of situations, but its direct addition into many plant-processing operations has opened tremendous marketing opportunities. In public bathrooms, there is a growing awareness of the need for odorless deodorization programs. Air ventilation, urinal cakes and mopping should be augmented by Metazene chemical control measures as a means of preventing complaints.
The VOC (Volatile Organic Compound) limitation is 18 percent in both states. All the ingredients are nonVOC, according to either vapor pressure (below) (.1 mm Hgo at 20oC), or by exemption (perfumes, up to two percent.). Hence, the isopropanol is always at 18.00 percent in three of the above examples. Paperwork submission will be required in both states. The level of perfume is subjective and influenced by fragrance/deodorant strength. It could vary from 0.20 to 2.00 percent.
The use of the above levels of surfactant should be reviewed. Much less may still give satisfactory results. The effect of surfactants should be evaluated from the standpoints of surface spotting, can corrosion and any effects from inhalation of “fines” in the air. Perfume selection can exert a profound effect on emulsion stability or instability.
The spray should be directed upward, toward the ceiling, and with emphasis toward those areas possibly having odorous residues. Additionally, specific surface spraying may be made, such as on toilet rims and the underside of toilet seats, adjacent walls and separators. Plastic containers and trigger/pumps without expose or contact metals components are the most desirable.
Aerosol dispensing is considered most effective for the control of airborne odors. The largest two aerosol cans (211 x 908 and 300 x 709) have net capacities of 894 ml (26.9 fl.oz.), and the product may be safely filled to 85 percent of this volume. A typical formula follows (Aerosol Formula for Air Freshener, page 54.)
The formula has a VOC content of 97 percent, making it unsuitable for California (after 1992) and New York (after 1993). Complaint formulations must be produced by January 1, 1992 and January 1, 1994, resp.; then marketers have an additional 18 months for “sell through.” The following formulations, with 70 percent VOC content, is suitable for use in California until January 1, 1996 and in New York until January 1, 1997 after which approved air fresheners must have a VOC content not exceeding 30 percent.
The non-VOCs in this formula include the first four ingredients, plus the HFC152a (CH3-CHF2). Since the last item, also known as Dymel A (DuPont), presently costs about $1.90 per pound in bulk lots, it may be replaced with methylene chloride if desired — the spray will then become slightly coarser, but still acceptable. To make the spray finer, use 20 percent S.D. Ethanol 42.02 and 32 percent Propellant A-46. The revised formula(s) remain at 70 percent VOC levels.
Two additional aerosol approaches can be considered. One has a hydrocarbon propellant, while the other uses dimethyl ether as the propellant. Examples are Aerosol Formula for 70% VOC Air Freshener, above, and Aerosol Formulas for 30% VOC Air Freshener and Aerosol Formulas for 30% VOC Air Freshener.
The density of the 70 percent VOC formulation is about 0.751 g/ml at 70oF. It follows that 507 g will fill a 300x709or 211 x 908 aerosol can to 675 ml, or percent of capacity at 70oF. This is equal to 17.9 Av.oz. Potential marketers may wish to label such dispensers as “Net Wt. 17.5 oz. (1 lb., 1.5 oz.)” and fill to a target and tolerance of 17.7 + 0.2 Av. oz. In order to comply with DOT, state OW&M, and Federal FP& LA regulations.
Similarly, the water-base, emulsion type 30 percent VOC formulation has a density of 0.854 g/ml at 70oF. One may then safely fill 576.5 g into the 300 x 709 or 211 x 908 can. Since this is equal to 20.34 Av.oz., a reasonable filling specification would be 20.2 + 0.2 Av.oz. for a label declaration of “Net Wt. 20 oz. (1 lb. 4 oz.).”
The water-based dimethyl ether 30 percent VOC formula may be identically labeled. In the process of deodorizing and freshening the air in industrial or institutional sites, these large-size aerosol cans may be used in smoke-filled lounges, lavatories, locker rooms, etc. In some cases, odors indigenous to the facility will creep into office areas. When they become noticeable, they can be banished by the use of manual or automated Metazene sprays.
In some cases, a super-strength or industrial grade aerosol product may be needed, so that much larger areas may be treated without unduly depleting the dispenser. A formula is now given for a tremendously effective product of about four times the normal consumer strength. Areas reserved for the temporary collection of storage of industrial waste often generate bad odors.
For example, meat trimmings, grass or vegetable cuttings, fish parts and other proteinaceous scraps will quickly decay in warm weather, producing both amine and thiol odors, along with those rancid, acidic and aldehydic malodors that arise mainly from oxidations. Such odors can be controlled to various degrees by spraying the area with Metazene, and control is enhanced if the top surface of the waste can is also sprayed.
For example, if malodors rise through the contents of a drum of meat clippings, then come into contact with active films of Metazene covering the top layer of waste, the blood, or “high” odor, will be chemically suppressed. The degree will depend upon the deodorant mix and the probability of source contract with animal products, such as meat, butter, cheese and milk, must be specifically approved and registered with USDA. The FDA administers similar controls for the remaining food products.
Industrial Odor Control Methods
Numerous other odors arise in many industrial settings, such as sewage plants, landfills and stack emissions, where large scale fogging generators can be utilized to control odors in the air for long distances. Machine ships often develop somewhat rancid odors from the air-oxidation of emulsion-type “white” cutting oils, such as those thinly jetted onto lathes, milling machines, grindstones, reciprocating metal saw blades, drill bits and the like to prevent overheating and galling. The heated emulsion, now often containing microscopic fragments of catalytically active iron and rust forms peroxide linkages at double bonds of the oil molecules, which then cause scission of the carbon-to-carbon bond and the formation of traces of butyric acid, iso-valeraldehyde and caproic acid.
All three of these examples are present in the noxious effuvium expelled by irritated skunks. The Latin root “capri” means goat. Caproic and capric acids were so named because their odors resembled the body odor of goats. When Metazene is added directly to the fresh cutting oils, cooling solutions of water based sprays are used to wet down areas that might come into contact with spent cutting oils. Here, the odor-counteractant reacts with the new, malodorous molecules as they are formed, and this may reduce the stale odor in the entire shop.
The odor-counteractant efficacy of Metazene can be readily demonstrated by taking small amounts of rancid butter or spoiled milk, dispersing them into very warm water in a test tube or small bottle, then spraying in some Metazene and shaking again. Most or essentially all of the malodor (without fragrance) will vanish.
Consumer And Institutional Applications
The recent development of an industrial strength 10.8 percent aerosol formula offers a demonstration tool for indoor malodorous areas. This formulation was effective when sprayed into a highly odorous perfumery laboratory.
In many cases, buildings will have persistent odors that result from the repeated use of various products. The stale food odors in the halls of some apartment houses is one example… the ethnic odors of tomato sauces, boiled cabbage, fish, cheese, garlic and onions are often prominent. Spraying the air with Metazene containing products is an effective method in place of traditional perfume sprays, which are only temporarily beneficial.
After the treated air departs (through drafts, or forced ventilation), the floors, walls and even the ceiling may exude more of the odor mix from the accumulation of months or years.
To a significant extent, these food, smoking and chemical odors revert into the renewed air over time. This unwanted replenishment can be both mitigated and deterred by treating these surfaces with Metazene sprays. For this type of treatment, a 10 percent Metazene solution in a hydroalcoholic solvent is preferred, and using a backpack compressed air tank and/or airless spray gun of the type often used by professional Pest Control Operators makes for the best application.
Metazene And Smoke Odor Counteraction
In some cases, multiple dwellings will bear the scars and empyromatic residuums of a past-localized fire or in the “smoking sections” of public areas. Spraying Metazene solutions either directly on the burned/smoke-damaged substrate or on the overlaying materials can reduce these characteristics miasmas largely unsaturated or aromatic amines. These treatments must be repeated periodically.
As a notation, all alcohol-based formulations are potentially flammable. Especially when large amounts are sprayed, resident evacuation and use of proper personal protection equipment should be used. Adequate ventilation must be assured, and the area must be free of flames or sparks, and should not be used around stoves, ovens, hair dryers, incubators, incinerators, nonexplosion-proof motors or sparking-type electric relays.
Many odors are produced by chemical degradations brought about by micoorganisms: bacteria, yeasts, mold, mildew, rickettsia and so forth. They include metabolic and catabolic mechanisms. Metazene has shown complete effectiveness in neutralizing organic odors such as cigarette smoke (pyrazines), fish odors (amines), decaying garbage and vegetables cooking odors, garlic and onions…sulfide mercaptans, thiols, etc. Metazene is organic in itself.
In circumstances where the microorganisms are accessible, the addition of disinfectant chemicals will allow Metazene formulas to provide an additional advantage, by killing the germs and other microphages that digest non-odorous materials and produce malodorous ones. The best control is obtained where they reside on hard, non-porous environmental surfaces. Surfaces where there is re-occurrence, such as mildewed work boots, and washroom walls and floor and pet accidents on carpet will have to be retreated at intervals.
Synergistic mixtures of certain quaternary ammonium compounds are notable for their persistent effects lasting up to six months on hard, non-porous surfaces. The addition of disinfectant concentrates to Metazene formulas is possible, keeping in mind the potential for can corrosion and the need for U.S. EPA pre-marketing approval. The latter process can be costly and take 36 months to complete.
Where bulk or pre-measured concentrated formulations are prepared by the janitorial staff for application using pump sprays or air guns, they may optionally include synergistic quaternary ammonium chloride disinfectant concentrates at the use-dilutions recommended by the supplier. At least 12 percent to 15 percent water must be included in the overall formula to avoid sporadic efficacy results and this means that any holdover amounts of Metazene bulk disinfectant formulas should be stored only in non-metallic containers, such as 5-gallon polyethylene buckets or drums, otherwise container corrosion could result.
Room Air Fresheners
Thermal and Gel-based fan air fresheners have resurged in recent years, and the addition of Metazene to plastic, oil and water-based formulations have proven to yield a dual effect: Vaporous odor neutralization and overall product longevity. Metazene acts as an excellent fragrance fixative.
Improved Consumer Product Acceptance
Most plastic contain chemical additives to impart such properties as improved stress resistance, non-yellowing, better molding properties, and opacity or color. They are not usually volatile, but when prilled polyethylenes, nylons and other “loaded” plastics are melted as a prelude to injection molding, the temperature of 250oF to 400oF cause some of them to vaporize.
The additives, plus any oxidative decomposition products, will then inject characteristic odors into the air; additionally, they may cause employees to have health related concerns. High-level ventilation is one remedy, but is often costly in terms of the capital expense, maintenance, and (for colder climates) the price of tempered replacement air. Counteracting the odors by means of Metazene spray is often a preferred option. One useful approach is to use a timed-dispensing device that mounts on some vertical surface near the source of the vapors.
Quite often, the still-hot plastic components are conveyed into fairly big corrugated boxes, commonly lined with a polyethylene bag to maintain dust-free environment during handling and shipping. This often caused the released additives, now as surface films, to gradually build up a saturated atmosphere in the shipper. This may be an embarrassment for the supplier if customers complain about the release of odorants in controlled areas. By briefly spraying each filled bag or box with Metazene, just before closure, the odor counteractant will combine with the malodorous vapors, neutralize them, and then polymerize into a miniscule amount so attenuated as to invisible.
Additives into The Manufacturing Process
The manufacturer of polyethylene sheeting, trash bags, laminates and similar articles will experience the same malodorous problems. Sometimes, over 25 percent of the composition will consist of additives such as those to improve low temperature flexibility and to prevent tearing. The sale of plastic trash bags represents a huge market, with over a half-billion sold each week in the U.S. alone. With scented trash bags becoming a favored option in controlling odors… the addition of Metazene with or without fragrance will provide better odor counteractant properties when injected into polyethylene, as well as providing the consumer with a superior odor control trash bag.
Metazene can also be added to other molded plastics that might require odor control during hot rolling, edge welding and so forth. The direct addition of Metazene into the process and/or spray can provide the manufacturer with a trace of pleasing fragrance (or no scent) instead of the raw chemical odor, when he or she opens the box. The difference has advertising potential as well. Similar remarks may be made for the automotive, carpet, rubber fabricating, paper-making, printing and textile industries, etc., where additives are inevitably used to prevent ozone-induced hardening and cracking of rubbers, premature yellowing of paper and so forth.
Many of these additives consist of odorous substituted thiazoles (vulcanizers), sulfitic bleaches, formalins, solvents, aromatic UV brighteners and so forth. They cause odors in both the plant and finished product. In fact, much of the odor of burning rubber is not the rubber itself, but the additives also present. The use of Metazene odor counteractant with or with the “Prescription Treatment” deodorants can be a powerful tool in combating such odors at all stages of production and use in addition to and offering excellent sales potential.
Other air freshening applications merely mask odors; Metazene annihilates the particles that cause foul malodors at the molecular level. When push comes to shove, there is no more effective molecular odor neutralizer in the marketplace today and can be applied to a multitude of products, including but not limited to thermal air freshener dispensers, aerosols, automated aerosol dispensers, paints, liquid and gel air fresheners, insecticides, inks, carpet cleaners, chemical specialties and processing additives, fabric softeners, laundry products, carpet emissions, automobile interiors, textiles, industrial deodorants for sewage and landfills, dryer sheets, pet odor neutralizers, carpet powders and cat litter, etc.
If you’d like to incorporate Metazene into any of your products or you would like further information on specific applications for Metazene, as well as further literature, logo-branded trademark licensing, MSDS data, pricing, etc., don’t hesitate to send us a message today!
Metazene is a registered trademark for an odor-counteractant produced by Alpha Aromatics, Inc. Pittsburgh, PA.