As the patch is curing, press a piece of 40 grit sandpaper over it, then remove it gently- - - -the texture of the sandpaper matches the surface finish of cast iron almost exactly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!