Patching an older NRS E-series
i was helping a friend patch an older NRS raft last night, and encountered something new to me. his raft is a gray color NRS E-135 around 10-12 years old, pictured below.
when doing the patch, i lightly roughened the surface with a small wire brush drill bit. to my surprise, the light gray color at the surface came off like a "skin" and then there was a darker gray colored rubber material below. this is different than what i had experienced when patching my blue color NRS Otters, as on my rafts the blue color seemed to be embedded through the entire thickness of the rubber material and there was no "skin" of color at the surface.
i roughened the darker gray material below the "skin" at the surface, and glued the patch to that. i think we may have to redo the patch (still has a slow leak, it is at a tough spot), so should i try to glue directly to the "skin" with a larger patch and not roughen the surface? or should i remove the light gray "skin" completely and glue a larger patch to the darker gray rubber material below as i did previously? i am not sure if there was a different technique to patch these older boats, so please offer any advice or experience. thanks in advance.