Originally Posted by
dddd
I abrade pretty deeply, until a consistent flat-black appears. A lot of work.
Not a lot of work if you cheat.
I use a sanding drum on a cordless dremel-type multi-tool for surface prep. Takes only a few seconds to get a nice clean area of virgin rubber. Using this, my patch success rate is 95+ % using Rema fluid & patches, even with the newer tubes.