“Palusol”, which is a trademark of Odice, LLC, is the brand of intumescent seal used on most gun safes. When exposed to heat from a fire the product’s thermoplastic covering melts. The underlying material then expands as a foam which makes a barrier to prevent heat and smoke from entering the safe. Palusol is a great product, but there are limitations.

Shown left to right are three types of Palusol: “PL”; “PM”, what most safe manufacturers use; and “EFV”, which has two small fins on it.

A miner issue is that sometimes the safe manufacturer’s employees do not handle the product carefully. Dirty hands, oil or drywall dust sometime keep Palusol’s adhesive tape from sticking to the safe. The Palusol then peels off and the consumer needs to glue it back into place.

More importantly, doors on some gun safes fit so poorly that the gap between the door and the frame is too big for Palusol to fill when it expands. In this case, heat and smoke will be allowed to enter the safe even after the seal expands.

Odice’s sales material states that for best protection, Palusol PM should be installed flush in a routed groove to direct the expansion of the material properly. None of the safe manufacturers install Palusol this way.

Odice says that Palusol should not be exposed to temperatures greater than 104 degrees for extended lengths of time. It seems, then, that Palusol might lose its effectiveness when the gun safe is in a garage in a part of the country where the temps get that hot.

Here is the biggest problem: Odice states that Palusol is activated at temps between 212 and 302 degrees F. That means that smoke and heat perhaps as high as 300 degrees can pour into most gun safes until the seal’s thermoplastic melts and the inner material expands. In many house fires one part of the house can burn while other areas do not. But the black sooty smoke infiltrates the entire house, and the safe. We have seen a number of gun safes which were not damaged by heat, but whose contents were destroyed by smoke and low level heat, because the seals did not get hot enough to expand.

So then how do you get real fire protection? Buy a gun safe with a door that fits well, and which has two seals. A cold seal or smoke seal is critical because it works all the time – before the expanding seal actually expands. Pictured above is the frame of a Fort Knox Defender. The black stripe on the left is Palusol PM, but to the right is a fire resistant fin-type seal which makes the safe airtight all the time. Infiltration of smoke, and air from 212 F to 302 F, will be greatly reduced.  On American Security safes there is a foam compression-type seal which accomplishes the same thing.  But most gun safes, even expensive ones, do not have the important second seal.

Most gun safe manufacturers use Palusol brand intumescent fire seals, commonly called the “expanding heat seal”. Palusol is a copyrighted trademark of Odice, LLC. There are several variations of the product with slightly different characteristics, and several thicknesses are available. I believe most gun safe and vault door manufacturers use the “PM” product.

According to Odice’s sales materials Palusol PM is hydrated sodium silicate material coated on both sides with epoxy resin, the core is reinforced with glass fiber. It is encapsulated in a rigid thermoplastic profile. Self-adhesive tape on the back allows quick installation. The appearance of this seal is a shiny clean straight line on the edge of the door or on the frame of the gun safe.  At least one manufacturer uses a variation that comes in rolls rather than rigid strips; it saves time in production, but looks cheap.  Pictured is the edge of an American Security BF safe door showing the rigid version Palusol seal right behind the 1/2″ plate steel door front.  Tape over the corner keeps the strips from coming loose.  In addition, taping over the cut ends of the Palusol prevents air and moisture infiltration which can cause deterioration of the product.

When exposed to fire Palusol’s thermoplastic covering melts. That allows the sodium silicate material to expand, filling in gaps between the door and frame of the safe. It becomes a rigid non-combustible foam with a high level of thermal insulation. According to Odice this expansion is equal to, or greater than, five times the material’s original thickness (not eight times thicker as claimed by a number of gun safe manufacturers). This makes for a barrier to the passage of fire, hot gasses, smoke, etc.  Palusol has been tested by independent labs.  Under normal conditions it has been shown to be effective for at least 25 years.

The next post will talk about limitations of Palusol seals in most gun safes.