Fireproof Safe History
Fireproof safes are used to protect jewelry, money, and vital documents in case of fires that may otherwise destroy such property. Businesses use fireproof safes to protect their most valuable and necessary documents, while homeowners often buy smaller fireproof safes to protect their own important papers or other valuables.
Today there are many different types of fireproof safes, all with different grades that show what kind of heat they can withstand. According to the Early Office Museum, fireproof safes were originally designed in the mid-1800s, and used various clay and mineral coatings that proved much more heat resistant than the iron normally used for the safe bodies. Another breakthrough was made when safes were manufactured with two different "chests," an outer layer and an inner layer for added protection. Eventually, older experimental materials were exchanged with plaster of Paris and other, better insulators.
These older safes gave way eventually to the modern steel alloys and synthetic compounds used to make fireproof safes today. These safes are usually rated in terms of temperature and hours. Temperature corresponds with how many degrees of heat a safe can withstand inside (not outside, where the heat is much higher) without compromising any of the materials, especially paper. Standard fireproof safes, for instance, only allow the materials inside to reach 350 degrees Fahrenheit or below. A 125-rated safe only allows the interior of the safe to reach 125 degrees of heat, and are used more exclusively for media made out of fragile plastics.
Safes are also rated by the hour, as effectively shown by the Keystone Safe Company. This rating does not mean the safe has a certain lifespan during a fire, but that the safe structure was tested for that specific amount of time. A 350-degree safe at 2 hours, for instance, has been tested and found to keep the interior temperature below 350 degrees for 2 hours with an outside heat usually around 1700 degrees Fahrenheit, much higher than the common fire. This does not mean that after that time frame the safe will fail, it just gives a general idea based on how well the safe tested. Manufacturers control the strength of fireproof safes by adjusting the thickness of the steel, the seals, and the insulating paints used. Safes with higher ratings are naturally more expensive, but a safe with a standard or lower rating is usually sufficient for a homeowner.