What is a gasket sealer and what a glass sealer casket?

Sealer caskets, also called protective caskets, are coffins which can be closed in such a way that they are air and water tight. Originally, most sealer casket were glass sealers, having an inner glass lid. Today most sealer caskets are gasket sealers.

Metal caskets - or metallic liners inside of wooden casket - can gain some protective property for the remains against the intrusion of ground water and insects through a hermetical seal. Nowadays most protective caskets are sealed by a gasket which is placed between the base (or body) of the casket and its lid. The gasket usually consists of an approximately inch wide one piece strip of flexible but resilient rubber-like material which runs along the upper margin of the frame of the casket's base. In a casket with a split lid (half couch casket) an additional gasket between the two halves of the lid is needed for effecting a hermetical seal.

When the casket is closed by the funeral director, a pull down and locking mechanism draws the lid onto the base and fastens it there, so that the gasket can form a seal. Caskets typically lock with a catch-type lock, which is composed of a locking pin and a receiving element. While the locking pin is attached to the lid of the coffin, the receiving element is attached to the frame of the casket's base. Some casket locks can be seen as little boxes with a lever or a keyhole the outside of the coffin, other locks are invisible because they are mounted on the inside of the casket. Usually the locking mechanism is operated by a crank or key. If the locking mechanism is mounted on the inside of the casket, access is gained from the outside through a keyhole and a tube possessing an air and watertight seal or valve.

Some caskets use other sealing mechanism than gaskets. Copper deposit and cast bronze caskets often use a chemical cement which is placed between the lid and the margin of the casket's base. Another (old fashioned) method for effecting a hermetical seal in a metal casket or inner metal liner is the connecting of the casket lid and the casket's base by soldering: the two metal parts are joined together with a heated soldering device like a soldering iron or a soldering torch by melting and flowing a filler metal (solder) into the joint. This method is primarily used for effecting a hermetical seal of zinc caskets used for international shipment of remains.

Most sealer caskets nowadays are glassless sealers, which means that they do not possess an inner glass lid. In former times, most sealer caskets were glass sealers: the protective property of the casket was effected by an inner glass lid, the metal frame of which was sealed to the margin of the casket's base by soldering or by screwing it air and watertight upon the base of the casket. In more recent times, the frame of the inner glass lid was connected to the margin of the casket's base by a gasket. Glass sealers have become rare in modern caskets; some luxury bronze caskets still have inner glass sealers offering additional protection.

In the US, currently the majority of burial caskets is probably of the non- proctective type, either because the caskets are made of wood and do not possess an inner metal liner or because lower priced non-sealer metal caskets have been bought. On the other hand, about one half of all metal caskets are sealer caskets. Metal sealer caskets are noticeably more expensive then non-protective ones. Although the sealing gasket costs the casket manufacturer only a few dollars, the construction of the casket including the type of metal used and the type welding employed is more costly. In the United States, it was the Batesville Casket Company which pioneered the production of reasonably priced gasket sealer caskets after the Second World War. Although a sealer casket might provide the mourners with the peace of mind that their loved one is protected from the elements for a longer period of time, there is a trade off because a hermetical environment can speed up the decomposition in a sealer casket as the remains are prone to destruction by anaerobic bacteria (bacteria living without oxygen) and to dehydration or to the formation of mould. There is also the danger that a sealer casket which does not have a valve or a gasket which works like a one way valve which releases the gas out of the casket while preventing the entrance of air and moisture can explode after some time. This can happen when the effect of the embalming no longer persists and the soft parts of the corps are partially liquefied under the formation of gas. Even in higher priced sealer caskets the protective function does not last forever because on the long run, even these caskets are prone to rust or other forms of deterioration.