Hello Everyone;  In response to Andy Taylor's question of where to
obtain the heavy primer filler for rough cast iron:

Any auto paint supply store or NAPA auto store carries "Lacquer Glazing
Putty" used in auto body repair work.  The NAPA part number is #6394.
It comes in a large toothpaste- type tube, and is a lacquer product.
It is red, like primer, thick like RTV silicone and goes on easily with
a plastic squeegee or credit card.

It's made to fill gouges, pinholes, and imperfections.  Use caution,
however, as it hardens like steel, so don't apply it where you don't
want it! (Lacquer thinner will remove it while it is still soft.)
It can fill rough areas as thick as 1/16 inch.

Depending on the thickness applied, time to harden will be from 30
minutes to overnight.  I suggest wet sanding with 120 grit wet and dry
sandpaper to quickly smooth down the dry putty.  It can then be painted
with lacquer or enamel after drying.

Roger Hughes, Texas
roghug@flash.net