Rusting Cast Irons

[Rooibos_Heals]

So cast irons are supposed to be rust proof with their procelin enamel, however, it seems that my cast iron is rusting. A friend of mine said it could be calcium build up, but I think it is rust because when i swipe a paper towel through it I get a dark brown and black color and I do not feel a smooth porcelin enamel finish. I think that it is possible for cast irons teapots to rust with heavy use because with constant moisture many people seem to agree that the enamel may wear away. Pehaps this is why cast iron instructions usually stress not leaving tea in the pots overnight or for long periods of time.

My question to my fellow tea chatters is what you think on this matter. Is it possible for cast irons to rust?

[Carnelian]

Cast iron is a notorious rusting material. The way my mother says to keep that problem away is;

1. never use a dishwasher
2. Wash with minimal-no soap
3. Immediately after washing place it back on a flame to dry

[procarel]

It is important to dry a cast iron pot quickly but I would be cautious about putting a cast iron pot on the stove to dry it if it has an enamel finish since that could cause the finish to come off. Using hot water and then towel drying immediately should prevent rust from forming.

[Rooibos_Heals]

I think the problem is actually keeping the tea in there. Some tea shops always have cast irons running, by keeping tea in there all day, I think the porcelin enamel wears away, just as it has in my teapot, it not longer has a smooth dark shiny black finish but instead a rough brown scaling one.

[jogrebe]

What types of tea do you brew in your tetsubin? I think there is a good chance that the black stuff you are getting on a paper towel is not rust but tea. While I do a quick wash of my teapot after each use, every so often I do a more complete wash with a wet paper towel (and q-tips for the spout) and they always get covered with the brown/black tea residue they clean off of the pot. I'd say don't worry about it and taking a closer look at my tetsubin under a good light it appears that only the very bottom is actually covered in enamel which is probably where its most likely to collect water/tea as its never completely empty once you poured out everything you can get.

[keelyn]

Is it possible for cast irons to rust?

Absolutely. It's iron. With continued exposure to air and water iron oxidizes into rust. Even stainless steel can rust if its poorly made.

Is what's on your pot rust?
Maybe. Maybe not.

Rust is reddish-brown and brittle, just like what's on that abandoned car down the road. If the inside of your pot is rusting, I'm pretty sure you'd also taste the iron in your tea. If it's rust you might not wanna use your pot for health reasons as well as flavor reasons. (mmmm....heavy metals...)

If not, it could just be tea build-up like Jogrebe said.

[jogrebe]

This place has a good set of care instructions for Tetsubins.

In the rare chance that it is in fact rust, my tetsubin comes with the following instructions in the folding "tag manual":

"If the care instructions are followed, your teapot should not rust as the inner surface has been coated with black enamel. However, in the unlikely event that your teapot should rust, your teapot can still be used. The rust is non-toxic and face. Use a soft brush to clean the rusted area, then fill pot with used tea leaves and boiling water for 20 minutes. The tannic acid in the tea reacts with the rust and forms a natural seal against future rusting."

[jzero]

Enameled cast iron shouldn't rust unless the enamel has been damaged.

Bare cast iron can rust even being allowed to drip dry. Always towel-dry bare cast iron immediately after washing.

I have found that a 3M Dobie Pad is great for getting out tea residue, and the Dobie Pads are gentle enough that some cookware manufacturers recommend them by name even for cleaning non-stick surfaces.

You can also use Barkeepers Friend which is a "gentle" cleanser. I routinely use it on my enameled kitchen sink and I occasionally use it for really stubborn stains on my Le Creuset. I would not recommend using BKF on a daily basis (some people claim that even BKF will wear out the enamel eventually, although others claim to have used BKF after each use for years), but for occasional removal of stubborn buildup it should be fine.