I have a wonderful, heavy cast-iron griddle.  I know how to season it
with vegetable shortening and have done so, and it works wonderfully. 
However, I am unclear whether it's possible to care for my cast iron
too much, and subsequently do more harm than good.

Eventually, the manufacturers say, I'll get a lovely black sheen on my
cast iron cookware, and this is a sign of "healthy" cast iron.  It's
nearly non-stick, too.  But I've been using my griddle now for about a
year and am still working with the cooked brown cast-iron color.
How long does it take for the famous black color to form?

Worse yet, my griddle seems to be rusting.  There are several possible
causes.  How do I keep it from rusting?
The whole point of washing cast iron only very rarely is to keep a
film of fat on the iron, protecting it from water and rust.  So I
don't wash it with water or soap.  Generally, I just rub it with a
towel, often with some salt in order to rub off stuck crust of cooked
food.  (Or am I supposed to leave the stuck crust on the iron, and
this creates the black sheen?)  I use oil or butter every time I use
the grill, and occasionally just heat some oil on it without cooking
food in order to try to keep it healthy.
It is a two-sided griddle, so sometimes I turn it over to use the
bumpy grill side.  My stove is a gas stove, and one by-product of
burning natural gas is water.  So while I'm happily using one side, is
the gas flame rusting the underside?

Now that it's rusting, how do I remove the rust?  I've been using a
steel brush.  How do I know when I've removed enough rust?  Is rust
something that "begets" itself, meaning that if I accidentally don't
remove it all, the rust will return more quickly?

I store the thing either on the cooktop or in the plate-warming drawer
underneath the range.  I don't wrap it in paper towel, though some do.
 It's humid where I leave right now, near boston.

What to do?

Hi katten--

Don't give up on your cast iron griddle.  Cast iron cookware is great,
you just need to learn a few tricks.  There's a whole lore associated
with cast iron and much of it is oral tradition.

I've been cooking with cast iron for decades and some of the pans I
use (I have 10 cast iron pots and pans) were my grandmothers.  Others
came from the local hardware store.

I've provided several websites for you to visit that have good
information on seasoning and caring for cast iron.  But let me also
share my experience and collected lore with you.

First, it takes a long time -- 50 to 100 uses -- to fully season a pan
and get that coveted black finish.

Most "old timers" will tell you, and I strongly agree, that animal fat
(bacon or lard) is the key to good seasoning.  If for some reason you
don't want to use animal fat, use Crisco.  Vegetable oil tends to get
gummy and just doesn't do the job.

NEVER use soap on and never soak cast iron or put it in the
dishwasher.

Don't use a harsh scrubber, it scratches the seasoned surface.  I've
found that a wok scrubber ( a bundle of twigs, actually) is great.  If
you can't find one of those, use a scrubber made for Teflon.

As redhoss-ga pointed out, salt is not generally a good idea,
although, I have used it as an abrasive in dire circumstances.  If you
do, be sure to rinse and rinse again.

As for your current rust problem:

Sand the rusted parts to shiny metal, then re-season the pan.

This next may be the key to avoiding rust: 
After each cleaning, briefly heat the pan to evaporate any residual
moisture.

If you store the pan nested among others, put a paper towel between
the pans.
In the current damp climate here in the Northeast, you may want to use
a paper towel all the time.

Here are some websites with more extensive information:


Caring for Your Cast Iron Cookware
Compliments of Lodge Manufacturing Company
World's Largest and Oldest Producer of Quality Cast Iron Cookware

How do I season my other Lodge cookware? 

1. Wash utensil in hot, soapy water. Use soap this time only. Rinse
utensil and dry completely. Discoloration on towel is normal.
2. Apply a thin, even coating of melted shortening (Crisco, Wesson,
etc.; do not use butter or butter flavored shortening) to the utensil
with a soft cloth or paper towel. Apply inside and outside (NOTE: If
your utensil has a lid, make sure you season it as well.)
3. Preheat oven to 350 degrees. Place utensil on top shelf of oven,
upside down. Place aluminum foil on a baking sheet and put on bottom
shelf of oven to catch any drippings. Bake in oven for one hour, then
turn oven off and let utensil remain in the oven until cool.
4. To clean utensil after use, use boiling water and a plastic scrub
bun or brush. Do not use soap, unless you are going to repeat the
seasoning process. Do not put in dishwasher.
5. Always wash immediately after use, while still hot.
6. After washing utensil, dry thoroughly, then spray lightly with
vegetable oil, (Pam, for example), wipe with a paper towel, and store.
Never store utensil with lid on. (Cast iron needs air circulation.)
7. Do not use utensil as a food storage vessel.
8. To remove heavy food or grease build-up, scour with steel wool, SOS
pad, etc., then re-season.
9. Deep fry in Dutch ovens at least six times prior to cooking beans
of any kind. Re-season utensil after cooking acidic foods, such as
beans or tomatoes.
10. Follow these simple steps and your Lodge Cast Iron Cookware can
last a lifetime.


Seasoning is an on-going process. The more you use your cast iron, the
better seasoned it gets.

A newly seasoned piece of cast iron cookware may have a brownish,
caramel-like color. This is normal. Over time and use, your cookware
will become shiny and black. TIP: The first few times you use your
cookware fry bacon, etc. in it to achieve a better, seasoned interior.

http://www.dutchovencookware.com/lodge-cookware.html

---------

Store your cast iron cookware with the lids off, especially in humid
weather, because if covered, moisture can build up and cause rust. Be
sure that you place a couple paper towels inside to make sure that any
moisture that forms will be absorbed by the paper towel.  If your old
or new cast iron pans gets light rust spots, scour the rusty areas
with steel wool, until all traces of rust are gone. Wash, dry and
repeat seasoning process.
http://whatscookingamerica.net/Information/CastIronPans.htm

Pans needing Re-Seasoning

If the pan was not seasoned properly or a portion of the seasoning
wore off and food sticks to the surface or there is rust, then it
should be properly cleaned and re-seasoned.
Remove any food residue by cleaning the pan thoroughly with hot water
and a scouring pad. I understand that heating the pan first to a
temperature that is still safe to touch helps open the pores of the
metal and makes it easier to clean.
Dry the pan immediately with dish towel or paper towel.
Season the pan 
http://www.kitchenemporium.com/info/castiron.html


If it *does* rust, sand all the rust off 
with medium-fine sandpaper down to the bare iron.  Season 
immediately, before oxidation has a chance 
to get to the bare iron. 
http://food4.epicurious.com/HyperNews/get/archive_swap19401-19500/19413/3/1/1.html


Search strategy:  "cast iron" cookware rust; "cast iron" cookware
season

Nellie Bly
Google Answers Researcher

I use cast iron when I cook on fishing/camping trips and have never
had a rusting problem like you describe. I wash my skillet with soapy
water and a sponge scouring pad. I then rub it with a paper towel
soaked with bacon grease or cooking oil. I don't use salt to scrub
with and I will bet that that is your problem. Salt residue combined
with high humidity might cause severe rusting.