Packaging materials are often exposed to different environmental conditions including humidity changes and condensation.

Timber is one of the most commonly used resources in the packaging industry, but is also one of the most vulnerable to decay. This is because it is a good source of sugars and moisture that many organisms use as food.

Dealing with mouldy pallets is a common problem that packaging companies face. Mould generates additional costs and can cause significant delays in the shipment of goods.

Understanding mould growth

Research shows that timber surfaces with moisture content of at least 25 percent and storage areas with limited air movement create optimal conditions for mould to grow. To prevent this, the moisture of wood surfaces should not exceed 20 percent throughout entire shipping and storage process.

Some timber pallet customers believe that heat-treating stops mould. The process does kill it, but is mainly designed to eliminate insects and does not prevent potential future growth. In fact, it brings moisture to the surface of the wood, which creates an ideal mould-growing environment.

Dealing with mouldy pallets

You can dry the surface of wood pallets using air-drying or kiln-drying systems. Air-drying takes approximately 20 to 60 days depending on airflow, humidity levels and air temperature. Kiln drying is faster but expensive and can result in split boards.

Chemical treatment can also prevent mould. Copper-8-quinolinolate, copper napthanate and chlorine bleach can be used to this end. But bear in mind that customers of some industries including food and medical supply may not accept chemically treated products.

Alternative solutions

There are also a number of steps you can take right within your storage space.

Make sure you keep your pallets dry and clean. You should avoid storing them in a yard or enclosed trailer for an extended period of time. During the day the temperature is higher than at night when it reaches the dew point. This adds moisture to your pallets and promotes mould growth.

You can also consider using alternative types of pallets. Presswood, corrugated, plastic and metal pallets may be less vulnerable to mould than green hardwood pallets.

References:
http://www.mmh.com/article/dealing_with_moldy_pallets/

http://www.ukpandi.com/fileadmin/uploads/uk-pi/LP%20Documents/LP_Bulletins/Bulletin%20454.pdf

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