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Posted by Neon John on December 6, 2007, 12:16 pm
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On Thu, 6 Dec 2007 08:25:30 -0800 (PST), zeb7k@hotmail.com wrote:
>I'm planning to build what they call a masonry heater or Finnish
>heater. A problem is the cast iron doors required cost $800 and up.
>I'm an OK welder and I have plenty of scrap plate around. I'm trying
>to find out if it would be a good idea to fabricate my own doors out
>of plate.
Sure. That's the way I made the door to my central wood furnace.
>
>My concern right now is the finish: First question, is the flat black
>appearance of cast iron a black iron oxide or something else?
Depends. Cast iron comes out of the mold a dull grey color. It can be oxidized,
painted or use one of several other finishes. The burnt oil finish that
develops on
cast iron cookware when it is seasoned is quite tough and can be attractive.
That
finish will develop on non-cast metal too, as anyone who's ever been a restaurant
griddle operator can tell you.
>
>There are apparently more than a few phophatizing/bluing/parkerizing
>methods available but the few I've seen cant take 750F heat. My only
>other criteria is that I want a flat brown or black or dark gray
>color. What finsh or treatment (if any) is available to the DIYer?
If the finish matters a lot then I suggest polishing, perhaps bead blasting if
you
don't want a shiny finish and then coating it with one of the automotive ceramic
header coatings that are now available. These coatings are completely heat-proof
within the temperature range that steel can be used. The best coatings are
applied
by specialists where the coating can be baked. There are several DIY kits,
however,
that have gotten good reviews.
Something else you can do, something I did on my furnace door. I got tired of
the
door always being scorching hot. I therefore installed a radiant heat shield on
the
inside. It consisted of nothing more than a sheet of stainless steel mounted
about a
half inch off the inside surface of the door. Mounts were hunks of all-thread
welded
to the door. The metal blocked the radiant heat from the fire and set up a
semi-dead
air space between the shield and the door metal. Even with a fairly large fire,
the
door stayed cool enough that it could be momentarily touched.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Better to pass boldly into that other world in the full glory of some passion
than fade and wither dismally with age. -Joyce
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