I don't know how serious this is, nor what should be used to seal the cracks.

For example, it is used to seal the casing of electric meters.

Hot wax was used to seal and secure the packages.

The special plate will be used to seal the top of the cone.

The Fisherman's Ring is no longer used to seal anything.

Bottle caps are used to seal the opening of bottles.

This effect can be used to seal pistons and shafts.

Electrocautery may be used to seal the ends with heat.

Wax was used to seal letters close and later, from about the 16th century, envelopes.

Tar was used to seal the places where the skins joined.