How Reliable Is The Glass Of Water Contaminant X-Ray Test?

Metal detectors and x-ray machines may fall into the food inspection camp, yet both are very different technologies. One uses a radio frequency transmit receive system, picking up anything that’s conductive or magnetic, the other is a density discriminator, using light frequency at high energy to pass through a product to identify mass.

Both have their pros and cons. Despite their higher price tag, x-ray machines are still considered by many as being more effective within the food inspection industry as ‘they see everything’. Steve Gidman, president of Fortress Technology, says this is a common misconception and uses the glass of water test to scientifically explain why.

“Although an x-ray machine is a density detection system, there are certain things it can’t detect in a food product. Put any contaminant you may want to identify in a glass of water and if it sinks like a stone, it’s probably going to be a detectable element. If it takes its time or floats, it’s not going to be detected by an x-ray machine.

“Wood, feathers, bugs – they’re probably the most common contaminants in the food industry, yet are undetectable with x-ray. Some metals are equally impossible to see, such as the very thin aluminum used in Soda production. If you cut a can into three or four pieces, it’s likely none of these pieces will be detectable in an x-ray machine, either inside or on top of a food product.”

Steve confirms an x-ray will pick up the denser contaminants, such as stainless steel and ferrous, non-ferrous metals, but lighter ones, including magnesium and aluminum, and anything with a low density metal, will be difficult to detect.

“These machines may even struggle to pick up some glass and rock if they come from low-density sources. So take the glass of water test - it’ll pretty much give you the same result you can expect from an x-ray.”

Steve concludes: “If you’re keen to replace a metal detector with an x-ray machine, be mindful you’ll lose virtually all detection of very low-density metals unless a large ‘chunk’ presents itself. I’ve seen cases where people replace their detectors only to find half an aluminum can has passed right through their x-ray, which is a bit of a surprise."

“While this is a simple technology to understand - everyone can visualize a light patch and a beam passing through a food product, plus the machine gives a nice display of what it’s seeing - there’s a large misconception that an x-ray machine detects everything, which is simply not true.”

Fortress advocates x-ray machines should be a complimentary and secondary technology for businesses with specific needs. For instance, those where contaminants commonly used in specific types of food production do not detect well with a metal detector.

About Fortress Technology Ltd.
Fortress Technology Ltd. is a privately-owned Toronto based company. Fortress Technology is the only metal detection manufacturer that, since its inception in 1996, custom manufactures metal detectors to suit its customers’ needs, application and specification while ensuring optimal performance. Dedicated to their Never Obsolete Commitment, new technology is developed to be backwards compatible and accessible without having to purchase an entirely new system. Renowned in the industry for their speed, accuracy and simple operation, Fortress systems are used widely within a range of food industry sectors including bakery, meats, ready meals, dairy, confectionery, fresh foods, frozen foods. In addition to product manufacture, the company offers a range of before and after sales service and support services including consultation, product testing, training, preventative maintenance plans, spare parts and validation visits. Fortress is a global enterprise providing worldwide coverage from its manufacturing facilities in Canada, the UK, and Brazil.