Re-casting 19th century Cast Iron: What is acceptable (modern) source?

[racookpe1978]

Odd problem here, but I'd like your thoughts.

I am trying to restore the cast ornamental railing decorations at the corners of a cemetery near my house. No budget from the county or historic societies, it's a donation thing so money has to be considered.) Graves are from mid 1840's through 1880's so the decorative cast iron in the fence around the cemetery is probably that same time period.

1) I have recovered 12 of 24 of the broken fence railing caps from the dirt and cleaned them. Those pieces I can adequately re-weld using a high-nickel SMAW weld rod, then grind them clear so the outside finish "looks" as smooth as the original contours. First question: how do I re-coat/repaint the welded areas to match the existing "black oxide" of the original castings? I don't need museum-quality national archival perfection here, just something or some system that looks right from the road, but won't rust out in garish patches in the next 5 years. Simple galvanized primer and flat black paint?

2) From the recovered fragments I have found a local "metal artist" who can make the molds and produce replica's of the remaining 12 covers. His cost will be a little over 900.00 dollars, if I can get him the raw cast iron to re-melt.

What (modern) cast metals would be adequate for the purpose? Am I correct in assuming assume modern steel scrap will not cast properly in the mold - or am I worrying about nothing? (Assume a fragment size is a curved decorative arch approximately 6x6x1/2 thick.)
If I cut up scrap cast "iron" pipe, will that serve?
Obviously, I could find original cast iron pieces of that vintage (old stoves, pots, anvils (?), etc.) but I'd rather not buy antiques just to melt them.

 

[MintJulep]

If you are just going for "20/20" appearance (looks good from 20 feet as you are driving past at 20 mph) why worry about the material at all?

Aluminum, contemporary iron alloys, bronze, zinc... If you're going to paint it black it all looks the same.

Heck, you could probably do-it-yourself with silicone molds and casting resin.

 

[KENAT]

How about an old engine block or something?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ornerynorsk]

Check these people out. They are an ornamental worker's dream. Very prompt service and almost never out of stock.

http://www.kingmetals.com

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[SnTMan]

There was that guy in "that other forum" casting concrete...

 

[racookpe1978]

Yes, I've used KingMetals to get new castings when I build railings or staircases, but they (and other local casting wholesalers) have no interest when quantity = 12 (instead of quantity = 120,000 or =12,000). 8<(

Re-melting a few pounds of their "Chinese-quality" cast iron fittings might be a source for iron. But I figure it would be more efficient to use a busted cast pipe instead of buying and shipping cast ornamental iron parts retail from out-of-state.

I've used cast resins before (the Alumilite series of mold-making plastics and two-part casting resins) to make molds and plastic pieces for smaller parts , but never for an outdoor applications. "Artistically" since I've have found many of the original casting parts, I'd prefer to use those where I can back in their original spots. Here, I was planning on gluing together several small cast resin parts with the recovered iron parts to make a larger mold of the whole piece, then casting the whole replacement when I needed too.

 

[EdStainless]

I would suggest looking at casting Al.
You can buy castable Al alloys fairly easily.
You can melt and cast it easier, the temperatures are lower.
You can use plaster molds.

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Plymouth Tube

 

[swall]

If you go the recast route with your local metal artist, then KENAT's suggestion of cast iron engine block scrap as the metal source is right on the money. If you opt for weld repair/weld build-up, a carbon steel filler rod will yield a better color match than the high nickel rod. You could also use cast iron filler rod.

 

[ornerynorsk]

A trip to your local scrapyard should yield some good stock to start with. Personally, I'd look for malleable iron, pipe, cylinder heads and crankshafts, for good pourability.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[swall]

I would stay away from cast iron pipe and fittings. There is way too much material variability and the material will likely be contaminated with soil, hard water deposits, etc. which will generate a lot of slag in the melt.

 

[racookpe1978]

Sounds like I've got some homework to do. Thanks for the info and background.

 

[TheBlacksmith]

As I set here typing, I'm looking out the window at some of my garden artwork made of ASTM A-36. It's about 20 feet away. My go to is Rust Oleum satin black; looks nice and some of that stuff is over 5 years old and going strong. If you're painting it I'd continue to use the high nickel rod, color doesn't matter, but the mild steel rod is more likely to recrack. I think for simplicity and cost casting aluminum would be the way to go. Nobody's going to be checking your work with a pocket magnet like they do with restored cars ...

 

[EdStainless]

When they re-made cast iron grill work for the Carson Prairie Scott store in Chicago they took down some of the CI pieces and used them to make plastic (foam material with plaster wash) molds. then they cast replacements in Al. Very quick and easy to do. Not as strong but very durable.

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Plymouth Tube

 

[TomDOT]

If you don't fancy dragging an engine block from the scrapyard, what about some Lodge cast iron cookware? The price is pretty reasonable, and they've been casting iron for over a hundred years.