The insulation resistance between the electroded surfaces of an underwater transducer and the water within which the transducer is immersed is greatly improved by coating the electroded surface of the transducer with a layer of air-free, high-resistance waterproof material before bonding an elastomer covering over the assembly to serve as the outer housing.

A device, e.g., an electrical or electromechanical assembly, comprising a housing with a mechanism disposed therein which is potted by a cured mass of a self-leveling liquid composition. The composition comprises an actinic radiation cured first resin component and a subsequently cured second resin component which is non-cured under the actinic radiation conditions effective for curing the first resin component. Also disclosed is an appertaining method of making such devices. Depending on the depth of the composition which is to be cured in the housing, it may be desirable to utilize the self-leveling liquid composition as either a single homogeneous mixture of the first and second resin components, or, where the depth of the housing is greater than the depth of UV penetration, as a cured mass wherein the first resin component is in a separate and discrete resin layer overlying a lower resin layer containing the second resin component but not the first resin component. The proportions and cure conditions of the first and second resin components are such that the actinic radiation curing of the first resin component (i) immobilizes the resulting partially cured mass of the composition throughout the subsequent curing of the second resin component, and (ii) renders the resulting partilly cured mass of the composition impermeable to gas channeling void formation throughout the subsequent curing of the second resin component. Preferred first resin components include (meth)acrylate resins, and preferred second resin components comprise epoxy resins, e.g., epoxy resins curable at ambient temperature, or at elevated temperature by acid anhydride curatives.

A device e.g., an electrical or electromechanical assembly (62), comprising a housing (64) with a mechanism (66) disposed therein which is potted by a cured mass of self-leveling liquid composition. The composition comprises an actinic radiation cured first resin component (102) preferably (methacrylate resins, which immobilize the partially cured mass, and a subsequently cured second resin component (100), preferably epoxy resins, which is non-cured under the actinic radiation but curable at ambient or elevated temperature. Depending on the depth of the composition which is to be cured in the housing, it may be desirable to utilize the self-leveling liquid composition as either a single homogeneous mixture of the first and second resin components, or, where the depth of the housing is greater than the depth of UV penetration, as cured mass wherein the first resin component is in a separate and discrete resin layer overlying a lower resin layer containing the second resin component but not the first resin component.