The Challenge of Signage and Labeling for Food Processing
The standard cleaning and sanitizing practices required to guarantee food purity and quality precludes the use of most common signage and labeling products often found in industrial manufacturing facilities. In particularly sensitive areas; environment, health & safety (EH&S) managers are forced to either:
1. Frequently replace failing labels which creates a risk of contamination in foodand beverage products or
2. Opt against labeling their facilities, potentially putting employees at risk of injury and their plants at risk for fines.
Many of the identification solutions in today’s market fall short because they neither remain intact under the harsh cleaning processes common to the industry nor are they detectable via the standard in-line metal detector contamination prevention systems.
Harsh Washdown Cleaning Process
To ensure cleanliness, most food and beverage facilities undertake routine washdown processes for production machinery and other surfaces that are potential sources of air and waterborne bacteria that may come into direct contact with food products. These cleaning processes often involve spray washing with extremely high temperature and pressure water jets, exposure to acidic and/or alkaline detergents and sanitizers, and scrubbing with the aid of abrasive tools. These procedures create an extremely harsh environment where only materials with adequate thermal, chemical, and mechanical durability will survive.
Most label constructions that are commercially available fail to provide all of these attributes. Many plant managers often resort to using steel markings or employing undependable labels that need to be replaced monthly or sometimes even weekly, as failure to catch a defective label can result in food contamination.
Metal detection is used in many of these facilities as a last resort to protect against product contamination. Many of the metal detectable label stocks that have been developed use aluminum foil for metal detectability. However, aluminum has poor alternating current (AC) field generation in comparison to steel and is not a recommended material for food and beverage facilities.
Aluminum is also vulnerable to oxidative corrosion when exposed to chemicals like acids and bases and when in contact with the steel surfaces, aluminum is also vulnerable to galvanic corrosion. This presents a problem, as steel is everywhere in food and beverage production facilities. Additionally, layered constructions are prone to delamination failures due to the difficulty in engineering interfacial strength between different materials.
Abrasion-Resistant Ribbons and Top-Coat
The main feature of any label is the printed information contained on the surface. These labels are designed to be printed using thermal heat transfer (THT) printable ribbons. While these ribbons are available in a variety of printer platforms, it is critical that the ribbon and topcoat are engineered to work together to produce the most permanent printed legend. To stand up to the abuses of common washdown processes, washdown resistant labels should be printed with ribbons that are constructed using robust inks and resins that will hold up to direct impinging sprays over 1000 pounds per square inch (PSI), in addition to rigorous scrubbing with abrasive pads.
Tough and Durable Facesheets
The choice of facesheet, which is the film that marries the topcoat to the adhesive, impacts the durability against the forces and stresses present during cleaning. Understanding this relationship has allowed Brady to develop two label materials that are extremely durable and that can be printed on demand. One of the solutions allows for a metal detectible element that is integrated into the construction of the label that avoids the delamination issues that plague similar products.
Metal Detectable Labels Should Meet Two Criteria:
1. The detection layer cannot be removed from the remainder of the label
2. A .” by .” piece of the label should have an AC field signature greater than a 2 mm ball bearing (Figure 3).
The aspects of a harsh washdown that cause the most failures in identification products include the high water pressures and temperatures used to remove dirt, plaque, and food residues. Most traditional pressure-sensitive adhesives found on labels will not endure these stresses for long. These forces allow more and more water to penetrate the edges of labels until complete removal occurs.
Metal detectable labels provide peace-of-mind to customers in the event that a label becomes detached or is tracked into an area from human movement, or in the unlikely situation that the label fails. The metal detectable feature of the label acts as an insurance policy to identify foreign debris that has made its way into the food production stream.
Be sure to choose materials that are specifically designed to remain durable in harsh washdown situations. Note however, that the survival rates are dependent on actual processes used and can be highly variable.
With that in mind, it is important to focus on two important criteria when selecting your washdown labels. First, the label must be engineered to remain in as large as possible to assist in detection. Second, the metal detectable component must remain with the label. Brady’s ToughWash™ metal detectable label incorporates both of these elements.
This information contained herein is excerpted from material developed by Brady Corporation, titled:
Metal-Detectable and Washdown Resistant Identification Solutions for the Food and Beverage Industry, by Alec Davis and Brien Christopherson. © 2013 Brady Worldwide, Inc. All Rights Reserved.
Cramer, M. M. Food Plant Sanitation: Design, Maintenance, and Good
Manufacturing Practices;CRC Press: Boca Raton, FL, 2006.
Deutsche Insitut fur Normung e. V. Retrieved July 15, 2013 from
Edwards, M. C. Detecting Foreign Bodies in Food;CRC Press ; Woodhead Pub.:
Boca Raton; Cambridge, England, 2004.
Etienne, G. Principles of Cleaning and Sanitation in the Food and Beverage
Industry; iUniverse Inc: New York, N.Y., 2006.
Marriott, N. G.; Gravani, R. B. Principles of Food Sanitation; 5th Ed.; Springer:
New York, N.Y., 2006.
Pearsio, D. Preventing Foreign Material Contamination of Foods; Blackwell
Publishing: Ames, Iowa, 2006.
Yamazaki, S.; Nakane, H.; Tanaka, A. IEEE Transactions on Instrumentation and Measurement 2002, 51, 810–14.