Jeff Fayne wrote:
> You have a better background in chemistry than I do, maybe you can answer this
> question:
>
> I've seen some products that claim to convert MINOR rust into a weldable
>material.
> >From my understanding it converts the oxide into some other form of metal
>creating an
> alloy. True or do I have it wrong? I was leery of it, so I ended
> cutting/grinding/sanding/media blasting the rusty bits away.
>
> Care to educate us non-chemists?
I'm no chemist, just a geologist (in at least one life). I had to study
minerals,
including limonite -- which is one form of iron oxide. Another form is
hematite,
the stuff they make jewlery from. (Great grammar, eh?) Both are oxides and both
are hard.
Personally, the biggest problem with rust is that it has thousands of times
as
much surface area as iron. It's because of the shape of the crystals. More
area
means more places for NEW rust to grow. That's why it's SO hard to contain.
I have used POR-15 with great success but only if BOTH sides of the rusted
metal are coated. You have to, in essence, seal the dammaged area away from
moisture. POR-15 is like RTV, it absorbes water to cure. That way, it
chemically
binds all the moisture in the rust so that no new source of oxygen is
available. It is
NOT weldable. That must be another product. There is a weld-through zinc
chromate primer. They used that when they repaired the body bits on my 308.
I didn't see the process as the car is in Dallas and I am in Tulsa. Photos were
taken but I haven't seen them.
Back to the question: "cutting/grinding/sanding/media blasting the rusty bits
away"
is the only correct solution, IMHO. You did good.
Rick
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