Food-safe pens for use in food-processing plants come in two styles. One has a metal housing, where the barrel, clip, and other exterior parts are all metal, and the other has plastic-style housing, where the barrel is plastic, and the clip and other exterior parts may be plastic or metal. As long as the pens are all using materials certified as food safe, you can choose either type in a pinch. But when you have a chance to evaluate what you want to get, there are a couple of things to look out for.
Metal Is Less Likely to Disintegrate
Metal barrels and other parts of the pen housing are less likely to disintegrate. No metal pen barrel is immune to all potential damage, but it takes more effort to create enough damage to the metal to produce shavings. And if that happens anyway, the metal is detectable, and the contaminated batch of food can be pulled off the line easily.
Plastic Housing Must Be Shatter- and Splinter-Resistant
You can get detectable pens with a plastic-style barrel, but the plastic must be resistant to shattering and splintering. Even a little bit of plastic in someone's food can make them upset because, on the customer's end, it shows carelessness in the production process. Plastic barrels are often a little more grippy than metal barrels, but you still have to be careful as dropping the pen on the ground can expose it to contaminants that you wouldn't consider food-safe.
All Materials Must Be Safe for Food Contact
No matter what, every bit of material in the pen should be approved as safe to use around food. It should be safe for food contact, including the use of food-safe ink, and all housing materials need to be safe to use if the pen drops onto food, for example. Food processing may allow for a certain range of contamination of various materials (for example, California allows up to a certain level of lead in food, as a recent report on heavy metals in chocolate showed), but that doesn't mean you want to add more. Using pens that are made of food-safe and detectible materials also shows the public that you are paying attention to small details when food safety is of concern.
Take a good look at where the pens are used in your facility because that can help you choose between the materials that make up the barrel and other parts of the pens. You may decide on metal-detectable food pens for use right by the food lines and shatter-proof plastic in nearby offices, for example. Order a few and see how they work out; if there are no issues after a few weeks, order more so you have a good backup supply.