Electrical bonding surface and sealant

[maflroy]

Fay surface electrical bonding is achieved via contact of conductive surfaces.
One of types of BAC5117-6 says that sealants (certified per BMS 5-45 for example, manganese dioxide cured Permapol® P-5 modified polysulfide) should be applied between joined surfaces.
How does it work? Don't resin sealants act as water barrier and mainly dielectric substances? or these sealant are conductive (however per

http://www.ppgaerospace.com/

they are not in conductive sealants lists).
Is it sqeeze-out sealant from the joint to provide contact of conductive metallic surfaces? Then how the fretting corrosion is prevented?

 

[3DDave]

Since those seem to be proprietary standards, and the external references say it's polysulfide rubber, I'd go with the use I've seen in electrical connections - it's applied after making the electrical connection between possibly dissimilar metals, to prevent water from reaching the faying surfaces and corroding them.

We used it specifically for braided ground wire connections by cleaning the surfaces, attaching the hardware to defined torques, and then puttying over the connection afterwards. There was no sealant in the joint.