Black coating on cast iron cookware

Hi folks,
I bought a small cast iron pestle and mortar today. It has a black finish which isn't paint. It looks thinner than paint. Does anyone know
what the coating's called and how it is applied? Just curious.
Best wishes,
Chris
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Might just be iron oxide or perhaps a carbon deposit left over from the casting process.
DOC
wrote:

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On Sat, 19 Jan 2008 02:17:38 +0000, with neither quill nor qualm,

It's probably japanning, a type of lacquer. http://en.wikipedia.org/wiki/Japanning Lacquer is extremely thin, so when they say "heavy black lacquer", it is probably 1/4 or less the thickness of an enamel.
-- You cannot depend on your eyes when your imagination is out of focus. -- Mark Twain
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Christopher Tidy wrote:

Black "lead"?
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Christopher Tidy wrote:

It depends. If it is food grade cast iron the finish is likely regular corn oil that was applied while the piece was hot. Same process Lodge Cookware uses on there cast iron. Seasons the surface so it becomes non-stick.
If it isn't food grade then it could be simply thin paint. We used a dip tank and THINNED black epoxy to do axles for Garden-Way products. That stuff looked like black water it was so thin.
--
Steve W.

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JoanD'arcRoast wrote:

Yep. You mix the epoxy to spec, then thin it with acetone to the viscosity you want. Once the acetone flashed off the epoxy started to cure. Our normal procedure was to dip the axle then hang it to drip off excess. Then once the rack was filled it went into an electric bake oven for 15 minutes to drive off the acetone and speed the curing. Same procedure used in a lot of places for a fast cheap anti-rust finish.
Then we also had the opposite spectrum of finish. The throttle bodies and cover plates for the hottest 'Vette engine made in the 90's. The ZR-1. All the throttle bodies and cover plates were painted in our shop. They were a REAL PIA though. Degrease then masking on the bodies while the covers went for a spin in the tumbler. Then the bodies came out for powder coat. The covers went in and were sprayed with a base coat of argent epoxy with texture added. Then the plates were hand filed to surface the lettering and then sprayed with a clear epoxy with a flattening agent in it. Then baked to cure.
--
Steve W.

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JoanD'arcRoast wrote:

Cheap labor is one but the other was that GM and Mercury Marine spec'd them to be hand filed. PIA to do but they sure did look good. Plus it was a VERY limited run of cars so we only did a few runs.
Now EGR valves on the other hand...... I can still powder coat them in my sleep. Same with antenna masts and trim caps.
- Steve W.
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Steve W. wrote:

Thanks for the opinions. It doesn't look like paint or lacquer. It's really thin and hard. But I'm not sure it's corn oil either, because it doesn't feel greasy. Does corn oil feel greasy even after baking?
Best wishes,
Chris
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Christopher Tidy wrote:

Nope. It turns into carbon. Thin and hard.
--
Steve W.
Near Cooperstown, New York
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wrote:

I guess the real question, not seeing it, is does this coating look just like the coating on "pre-seasoned" cast iron pans in the camping or cookware aisle?
It's probably just standard "seasoning" as people are saying. Oil burned into the nooks and crannies of the cast iron. It requires maintenance, and never wash it with soap or anything thats seen soap.
I use a lot of cast iron in my cooking. I have 2 cast iron pans and a double sided skillet. As well as a nice Enamel coated dutch oven.
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I e-mailed the manufacturer to ask. Apparently it's just "natural cooking oil baked in a hot oven to season it".
Remarkable. I'm amazed that it doesn't feel greasy.
Best wishes,
Chris
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As the vegetable oil begins to oxidize, it first gets thick, then very sticky, and finally it oxidizes completely and takes on a property something like baked linseed oil. In fact, it's probably about the same thing. It feels completely dry.
Some iron cookware used to be sold black, pre-cured. I have some French steel sauté pans that came that way, which we bought 30 years ago, and one heavy cast iron Dutch oven, bought 40 years ago, that were sold in that condition.
I also have a large cast iron skillet, close to 40 years old, that was so encrusted that I sanded it all down to metal with an angle-head sander (not as easy to do as you'd think). Within two months of regular re-curings, it was black again.
-- Ed Huntress
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While my wife was on a business trip overseas (time to play ;-) ) I took a scrap cylinder of Stainless I had and dipped it into 30 wt motor oil, put it into a try (shop tray) and put it into our Propane gas stove. Selected CLEAN oven mode and went about cleaning.
The smell was just a little worse than normal - as the splattered grease was smoking also.
The color was liquor brown and nice looking. It was within the surface as a thumbnail could not detect the edge. I sponged out the oven and cleaned up my tracks - back to the shop - experiment done.
Think small heat treating oven - get red hot and slowly cool. Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Ed Huntress wrote:

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Motor oil probably had almost no effect here - first off, it does not behave the same way as vegetable oil, and second you get a nice range of colors on stainless simply with heat and oxidation - just hit a shiny scrap with a torch to see the available range of colors.

Too hot. Well past that nice brown. More of an ugly gray. Stainless colors at different temperatures than steel, for which the oxidation color ranges are fairly well known due to blacksmiths using them as a tempering thermometer.
A typical home oven on clean gets to somewhere in the 700F range, as I recall.
--
Cats, coffee, chocolate...vices to live by

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I've never seen a cast iron mortar and pestle, but the coating on cast iron cookware is burned oil or grease which you build up over time.
A new skillet which is actually grey can be turned black by coating it in oil or grease and burning it in the oven.
I've found olive oil works the best, but it takes more than one application and some actual cooking to get it completely black. As is claimed, they really to get better with age.
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