Proven Strategies to Inhibit Mold Growth on Pallets
Mold Prevention: Understand what causes mold on pallets and how different prevention methods work.
By DeAnna Stephens Baker
Date Posted: 6/1/2013
Preventingmold on wooden pallets has become increasingly more important as a growingnumber of pallet users demand pallets that have been treated to prevent thegrowth of mold.
If theproper steps are not taken, wooden pallets can be a fertile breeding ground formold growth for several reasons.
“Moldspores are everywhere,” said Dr. Brian Bond, associate professor of woodproducts at Virginia Tech. “They’re in the air all the time and in almost allenvironments. And wood is a good food source. Mold needs several things togrow. It needs a food source, it needs the right temperature, it needs moisturecontent, and it needs air. Wood is a good medium for that because the sugarsand starches in wood are a food source and the high moisture content in greenwood provides plenty of moisture for the survival of the fungus. And if thetemperature’s warm enough, which is pretty much over half of the year, it makesa great environment for mold to grow on. Most pallets are produced still in thegreen condition, so they are a prime source for mold growth.”
The keyto preventing mold grow is controlling one or more of these elements that moldneeds to grow. Controlling air is virtually impossible, and controllingtemperature is not easy either as the temperature range that is conducive tomold growth is also the temperature range that is most comfortable for workers.So that leaves moisture and food source that can be controlled.
“Ifyou’re going to eliminate one of those variables, reducing moisture or makingthe food source unavailable through chemicals are the most viable options,”said Bond.
Manypallets users think that heat treating pallets helps prevent mold growth. Butin reality, heat treatment is done to kills wood pests so that export palletscomply with ISPM-15 standard. It has little to do with prohibiting mold growthunless the pallet is dried to less than 20% moisture content. The heat treatingprocess can actually make wooden pallets or lumber more susceptible to mold, bybringing to the surface moisture and sugars that are necessary to facilitatemold growth.
Bondpointed out that there really is not one single method of mold prevention thatis the best or most cost-effective for all pallet companies.
“Thereare variables that influence that depending on the customer, use, the timeperiod and acceptance of the treatment method,” said Bond.
Forpallet companies that want to use a chemical treatment, companies such as ISKBiocides and X-Mold have options available. ISK Biocides offers two fungicideproducts that it recommends for mold prevention on pallets – PQ-80 and NeXgen.Both can be applied by dipping or spraying assembled pallets or componentsprior to assembly. PQ-80 may also be applied by electrostatic deposition.
Thoughchemical treatment of pallets is not government-regulated, some palletcustomers, especially those in the food and pharmaceutical industries, mayrequire that any chemical mold treatment be government approved. The activeingredients of NeXgen are registered with the Food and Drug Administration(FDA) and Environmental Protection Agency (EPA) for control of fungi on morethan 50 vegetable and fruit crops and for use in materials which may come intocontact with foods. The active ingredient in PQ-80 is allowed by the FDA as apreservative for wooden articles used in transporting, packaging or holdingagricultural products.
Moreinformation on PQ-80 or NeXgen is available by calling 800/238-2523.
X-Mold’schemical treatment, E-Fusion, is a protective coating that is applied with anelectrostatic spray booth. According to the company, the coating bonds to woodalmost instantly when applied using its proprietary electrostatic sprayingtechnology, creating a protective coat that is not water-soluble and willtherefore not wash off. All ingredients in the treatment are EPA registered andapproved and registered with the National Science Foundation (NSF) to be usedas a coating on wood pallets transporting packaged goods in and around foodprocessing areas, according to X-Mold. More information on
E-Fusion is available at http://www.xmold.net/
Onething to keep in mind with chemical treatments, is that they are usually“envelope treatments” – meaning they only treat the surface of the product. Soif any cuts are made after the treatment, that “envelope” is opened, meaningthat the product would need to be re-treated.
Ifchemical treatments do not seem like the right fit for a pallet operation,drying the pallets may be. Drying for mold prevention is different than heattreating a pallet. Heat treating gets pallets hot, but it does not dry them, asheat treatment standards are not designed for mold prevention. According toBond, a moisture content below 20% is usually sufficient to prevent mold growthon pallets, and heat treating according to ISPM-15 schedules will not reducemoisture content to this level.
“Thereare treatment chambers that have the ability to dry after treatment, but it’snot the standard practice,” said Bond.
Forpallet companies interested in drying pallets, there are options offered bycompanies such as Lumber Sales & Products and Big Ass Fans. Lumber Sales& Products has a relatively new product in its Air-Flow Trailer System(AFTS) which is a design for trailers that combines two strategically placedheavy-duty fans and 14 vents to create air flow through a trailer and controlmoisture in the trailer.
“Every30 seconds there’s fresh air circulating through the trailer,” said JimFrancois, president of Lumber Sales & Products. “All you’ve got to do isload up a semi-trailer and plug in the fans. It’s very simple.”
Dependingon the weather, pallets in a trailer will dry down to 19% moisture contentwithin four to five days, Francois said. Other benefits of AFTS is that it canbe used as a fan shed, reduces handling of pallets as they can be loaded oncefor drying, storage and delivery, and can also prevent mold in the traileritself. AFTS can be purchased as a kit that pallet companies can self-installin existing trailers, be installed by Lumber Sales & Products, or be purchasedas a complete trailer and system. More info on AFTS is available athttp://www.aftstrailers.com or by calling 262-677-9033.
Big AssFans has a similar concept. It designs high-volume, low-speed fans that keepair moving within a warehouse, preventing the buildup of moisture on surfacesthat might harbor mold by continually disturbing the thin sheet of stagnant airsurrounding each pallet. These large-diameter, low-speed fans use their immensesize—not speed—to move a massive amount of air using very little energy.According to Big Ass Fans, the fans are an efficient way to incorporate airmovement to large spaces with high ceilings and can easily be added as aretrofit to existing facilities. More information on Big Ass Fans is availableat http://www.bigassfans.com.
Acommon misconception among some pallet users is that once a pallet has beentreated, it will be mold-free forever.
“Howyou treat the pallet after a preventative treatment method is equally importantto preventing mold growth for future use,” said Bond. “Any preventativetreatment is not a lifetime treatment. Any preventative treatment is just atreatment that is going to last for as long as that pallet is kept at thoseconditions throughout storage, transfer and use.”
Thebest way to avoid mold on pallets is to choose a treatment that works well withyour process and your customers’ needs. Bond said that to effectively preventmold growth, everyone in the supply chain must be involved in the prevention.
“Theproducer’s got to be aware, treat it right, get that pallet to the user in theright condition,” said Bond. “But the user can’t assume that it’s a lifetimetreatment. They have to also respect the fact that if you expose it to thewrong conditions – i.e., leave a dry pallet out in the pouring rain – it’sgoing to pick up moisture.”
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