in the 80's i did some casting using polyester resin. i was hired to make
reproductions of the ornaments on the cast iron buildings in soho, new york
city. i was kinda making it up as i went so i have no idea of the longevity
of the stuff i made. i mixed iron powder into the resin before adding the
hardener. the finished castings *actually DID look* like cast iron, i was
amazed. they even rusted. thing is the iron powder is heavy and would
settle to the bottom of the casting if you had a long curing time. i mean,
not all of it, but it generally tended to start settling to the bottom, even
in the mixing bucket, and even with heavy doses of "thixotropic powder" etc.
but it was cool. and they did look like cast iron. i never thought to touch
a magnet to them, i'd bet they were magnetic. i got the iron powder from
some sort of scientific materials supply house, but i bet you could probably
find a place that sells it much cheaper. i'm sure there must be lots of
information out there about adding metal powders to resin castings. in my
case, you're not supposed to use polyester resin to do castings, it heats up
and i think i've heard it can even catch fire. i fudged it so i opened the
molds when the resin was cured enough to hold it's shape but before they got
too hot. i worked in fiberglass mat/fibers before closing the mold
(polyester is brittle and would snap like ice if you don't have some sort of
reinforcing material in it.)
when i was in college ('78~'82) there was a guy there who was making larger
than life size castings (of human figures) in polyester that had (lots) of
bronze powder mixed in. i think they called it "cultured bronze". looked,
more or less, like bronze. no idea there again of the longevity.
i'd think there'd be no problem mixing in iron powder. (but then again i
don't really know you're trying to do, i'd imagine if you were trying to
cast lucite ALL the iron would settle to the bottom before it cured.)
good luck. let's see some pics. ("cores", huh?)
If you buy casting resin, rather than laminating resin, you can cast thick
sections without it getting too hot. You also can reduce the accelerator
("catalyst") to keep it cooler but that's risky business, because, if you go
below the tolerable threshhold, the resin won't cure hard at all.
Casting resin is widely available from resin suppliers. It's usually much
clearer than laminating resin.
Iron powder has been used to fill epoxy for making short-run forming dies.
There have been entire books published about using filled epoxies
(aluminum-filled, mostly, but also stone aggregate and iron) for dies and
similar applications, but I haven't read one since around 1980, so I don't
know what's current.
> when i was in college ('78~'82) there was a guy there who was making
Not exactly iron powder, but you can buy a 10lb bag of #7 steel shot
Finer steel shot is used in shotblasting (like sandblasting). There
are many suppliers, don't know what a bag of that goes for. Google
and a couple of phone calls might be enlightening.
Ferrite powder is manufactured (it's a component of copier toner, among
other things). You might call Fair-Rite and see if they can sample you a
bottle. Failing a commercial source, fabricate a ball mill and grind
Without knowing the magnetic requirements, I cannot say if ferrite will
work for you.
I dunno about the ability to meet your requirements, but there are iron
powders available for various uses, from toys (Etch-A-Sketch), to industrial
uses.. electromagnetic clutches/brakes for machines.
These examples are moderately coarse powders.
Very fine iron/steel particles are a byproduct of etching/cleaning or
pickling steel products in manufacturing. The steel parts are pickled in
various acids, and the particles which are suspended in the liquids are then
filtered to remove the particles from the acids. The result is a
mud/clay-like material that is used to manufacture other products, including
iron composition cores for certain magnetic properties.
I don't have any sources to recommend.
The finest iron powders are called "carbonyl iron"
Googling for carbonyl iron brought up this supplier:
Many years ago, the ferrite factory for which I worked used oxide from
the steel mills as a raw material. I was told there were mountains of
the stuff in West Virginia.
To be usable for magnetics, the oxide would have to be fired in a cycle
that included high temperatures and witchcraft.
Zone refine. Melted in a magnetic field and the field is moved
slowly towards an end - moving impurities with it.
Expensive refining but quality product.
Similar to that of a semiconductor process.
Likely from the ferrite business.
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