seasoning cast iron

[MarkBillesbach]

I'm hoping someone can help me out. On a building I'm helping to renovate, we have a cast iron door sill plate in the main entrance door. It had all kinds of rust and old paint stuck to it. We removed it and glass beaded it and now we want to somehow season it. I was leaning for a dark finish. Would it work to heat it up with a torch and rub old motor oil on it? We really don't want it painted as it would get scuffed and scratched up right away. We're hoping maybe the oil treatment followed by hot wax might work. Any suggestions or ideas?

[Tom Martin]

Degrease it and wipe it down with a salt and water or vinegar and water solution, then let it rust. After the red rust forms, boil it in water and the rust will turn black. Brush or steel wool the loose rust off and repeat the rusting and boiling and brushing until it is dark enough to suit. Heat it up some and oil it down and you will have a fairly durable finish. Rusting can be accelerated in a rusting box which is large enough to contain the part, along with a pan of water and a light bulb to provide heat. Handle the part only with cloth gloves to prevent spotting due to oil contamination from bare hands that will cause spotting.

[Dave L M]

If you can fit it in an oven or bar b q grill you can season it just like you season a cast iron skillet with veg oil or even better bacon grease do a search on seasoning cast iron skillet and it will tell you how It takes several hours and a few applications an I found that a temp of about 250 works best good luck

[Kevin O. Pulver]

Mark,
I think your idea sounds like a good one. I'm assuming this thing is NOT coming out to be immersed in some way, and must be done on site.
Perhaps Tom's idea to rust it chemically before you apply the oil/wax, might be handier than the torch, perhaps not. The nice "blacksmith finish" that you've seen so much was of course done only by heat, and didn't involve any initial rust.
Be sure to take some photos for us.
Kevin

[Ronald E. McClellan]

Use gun blue! That is what is for. Start with a slightly diluted solution depending what you want. Ron

[gvasale]

or, you can "paint" it with boiled linseed oil, and it will take on a golden brown color like you see on some farm antique metal items. This has been used for quite some time and apparently has followers...

[MarkBillesbach]

The sill is almost 44" long, and I have it removed and cleaned. I don't have an oven or BBQ grill long enough to fit it in thus the question of using a torch. I like all the ideas you have given me, so I'll try a few of them on the bottom side and see how the results turn out. Thanks, Mark

[Mike Monnier]

I will try to post a picture for you tomorrow Mark. I received the exhaust flange for our 2hp Springfield on a Saturday afternoon. It had been sandblasted to give it some roughness after machining. I tossed it in the flower bed and started dousing it with vinegar. It rained Sunday night/Monday morning. I lightly brushed it with a brass wire brush on Monday night, "painted" it with used oil, wiped away the excess and installed it on the engine. I normally like to let this stuff sit up to a month, but it gave it a good patina that matched the rest of the engine pretty well. I didn't have much choice since we loaded it Tuesday night and headed out to the Coolspring show.

I'm currently doing the same thing to a new cast iron muffler. Vinegar alone gives it a nice dark color. Water brings out the orange rust and accelerates the aging process. I may have to help it along with a garden hose since there is no rain in the immediate forecast.

[Mike Monnier]

Here is the flange and half of the muffler that I mentioned. The lighting was a little tough when I pulled the engine out this afternoon, but you get the idea. The muffler has been treated with vinegar only as we haven't had a drop of rain here in a week.

[John C Walker]

What works for me to season cast iron is as follows. Grease all surfaces with bacon fat, put piece in oven at 300degrees for two hours, remove from oven and coat again with bacon grease and return to oven at 200 degree for one hour, your done.