If you use this--do not try to puddle the CI--fire off on the rod, let it wet in.
...ummm...thinking... for seal tight welding on CI--SI Bronze can have
problems-porosity, toe not wetting in good enough
On CI prep--grind or carbide burr for bevels on the CI edges to be welded
regardless of the method that's used.
One thing that really helps---on CI--after bevel prepping, is to
take TIG AC--low amp setting 5-10, just barely let the torch fire off to make a weak
dancing arc. Play the arc over the bevel prepped areas---you're looking for
cleaning action-ONLY. You don not want to see red heat. Littte bits of sh*t, will keep blowing off, keep moving torch around, not dwelling in any one area,
then go back to it. Can assist with ss brush as well.
This can do an impressive job of cleaning and de-gassing the CI surfaces,
with minimum heat input-no oxidation. With decent CI--this cleaning may create a honeycombed appearing surface--looking silver to chrome. That's bare-naked, CI that's normally never seen.
I've actually gotten crack bonding on really good CI--with out adding filler, just to see what would happen--filler was added.
[Yes--this is a method, darn few have ever tried or heard of. Anyhow, it's the best, low heat input method of prep I've found prior to silicon bronze, steel or nickel filler welding. CI welding with filler is ALWAYS a 'buttering' type of weld,
one's attempting to get some adhesive bonding to the CI substrate.
I'm curious if Peter (Castweld) has ever played with the above. ]