Cans are used for canned foods.

Most of us take canned food for granted, but metal food cans are a new invention.The canning materials of steel, tin and aluminum have evolved into products that are lightweight and versatile, and give canned goods a shelf life ranging from one to five years.Metal cans ensure that food is free of harmful substances.

Napoleon wanted his armies to have unspoiled food.The first glass containers were used to keep food from being spoiled when the jar was heated.The next step was to use tin cans.Lead-free steel was pressed into service once it was deemed unsafe.Cans go through a variety of processes to kill harmfulbacteria.

Most of the cans used for canned foods are made from steel.There is a thin layer of tin on the surface, but only 5 to 6 pounds of it per ton of steel used.The term "tin can" is still used to refer to this type of packaging.More than 1,500 types of food items are packed into steel cans.The easy-open type with pull-tabs on the lids is one of the newer innovations.Steel cans are 100 percent recyclable and made from a minimum of 25 percent recycled content.

The metal is easy to mold and is resistant to rust.There are pressures of up to 90 lbs.It's important for carbonated drinks.One way to distinguish aluminum cans from steel is to use a magnet; steel will stick to it, but aluminum won't.

Most metal food and beverage cans contain a chemical called BPA.The chemical is used to coat food cans.Scientists and health organizations are concerned about the safety of the food and beverages they sell.This is a problem becauseBPA has been linked to a number of health problems.Cans labeled "BPA-free" are a good way to avoid this danger.