An aqueous cold seal release varnish comprising the reaction product of a mixture comprising 30-50 parts of a polyamide block copolymer having an acid value of 30-45, 1-5 parts of an amide wax, 10-20 parts of at least one C.sub.1 -C.sub.4 alkanol, 5-10 parts of an amine and 15-55 parts of water. The mixture is dissolved by heating at a temperature of 75.degree.-85.degree. C. for a period of time of not more than 90 minutes to produce a varnish. An aqueous cold seal release lacquer (CSRL) is prepared from the varnish by mixing with a C.sub.1 -C.sub.4 alkanol, water and a surfactant.

In the representative embodiments of the several methods and apparatus of the invention, a barrier formed of a low-temperature fusible metal alloy having a selected melting point is arranged between the donor and receptor explosives in an otherwise-typical detonator for reliably blocking the transmission of detonation forces from the donor explosive to the receptor explosive until the detonator has been subjected to well bore temperatures which are greater than the melting point of the fusible alloy. By selecting a fusible metal alloy which has a melting point less than the known temperatures of the well bore fluids, when the tool is exposed to those elevated temperatures, the barrier will be predictably transformed to its liquid state thereby allowing the liquid alloy to flow to a non-blocking position away from the detonation path of the donor explosive. In an alternative manner of carrying out the new and improved methods and apparatus of the invention, means are provided to return the fluent fusible metal alloy to its initial detonation-blocking position between the explosives so that the fusible metal alloy will again provide an effective barrier for reliably preventing the detonation of the receptor explosive as the well tool is subsequently recovered from the well bore.

A combination gas generator and pyrotechnic separation device which causes separation of elements safely, quietly, quickly, and without the production of loose parts or release of combustion gases to the ambient environment. A tubular tensile element houses a quantity of pyrotechnic material which, when ignited, burns, fuses or melts a tensile element allowing the separable elements to break apart. High pressure gases generated by the combustion of the pyrotechnic material aids in separating the separable elements.

The present disclosure describes a latch assembly wherein structural members are coupled to each other by an electric match-type device interposed therebetween. The latter device generally comprises a body portion having electrical connections thereto and a rigid mass of combustible material firmly adhered to an extremity thereof. At least a pair of the structural members are individually coupled to the combustible material. Remote activation of the match by the passage of electric current therethrough results in the firing of the combustible material and the consequent opening of the latch through the elimination of the coupling force between the structural members.

This invention relates to a relesable attaching apparatus for attaching a portion of a first object to a portion of a second object. The attaching apparatus has an attaching member with walls defining a cavity therein. A rapidly expanding material is placed within the cavity such that when the material is caused to expand, the attaching member will break at a failure zone located adjacent to the cavity. The rapidly expanding material is a composition that undergoes a phase change from a solid to a liquid, wherein the volume of the liquid is larger than the volume of the solid. In operation, an initiator triggers the phase change which causes a pressure build-up in the cavity, thereby loading the attaching member and causing it to break at the failure zone. Accordingly, the first and second objects are freed from one another.