Collecting cast iron cookware would seem to be an odd hobby, and you'd probably be correct in thinking so, but take a look around at the other things people collect (Pez dispensers, match books, cigar bands, bottle caps, post cards, etc) , and it starts to seem more normal. It's something you can buy relatively cheap, clean up and use daily. A collection you can actually use without fear of hurting it. It's actually a collection that gets better as you use it.
You can see the cast iron items in my collection so far HERE.
Cast iron cookware fell out of favor when lighter aluminum pans and pots became popular, but cast iron seems to be making a comeback as people are tired of buying and re-buying Teflon coated non-stick aluminum pans over and over. Natural non-stick is becoming more attractive as people are trying to save money and to live more simple lives. Younger people into the "Retro" movement find that cast iron is now worth considering. You can spend $50 - $100 on a nice aluminum, coated pan and use it for five years, or spend the same money on cast iron pan that's already 75-100 years old that will last another 100 years. The term "Wears Like Iron!" comes to mind.
I've collected a few things in the past, things mechanical, electrical, things way more complicated than cast iron pots & pans. I've collected electric desk fans, and vending machines / trade stimulators. I still have what some would consider a very sizable collection of fans from the 1940's back. As far as vending machines I have a few rare items, as well as one of my Holy Grail items that if I sold it I could afford a sizable down payment on a new car. As a collector I try to find items that are rough, and in need of some love, and I can pick them up cheap, put in some work and make them like new. This is the fun. Seeing something go from almost a castaway item, to something that people desire and would pay top dollar for. Being a collector means that I'm not really into selling, but it's nice to know that you've done the work and made something from what most would consider nothing.
My collecting started off with my Mother passing down to me a No. 6, 3-notch Lodge skillet. It was heavy, she used it a lot, and the seasoning built up showed it. Next she passed onto me a No. 8 Griswold slant logo dutch oven, WOW! I love this one for cooking chili. Then came the National / Wagner Ware No. 9 skillet. I use this skillet almost daily. It's become my go to skillet. It's just about the perfect size for everything. It has enough room to move around in. I have much older, much rarer, much nicer skillets but this one gets used. Mom gave it to me, it works great, and that's that. My parents both collect Fiestaware, so I feel slightly more normal talking to them about my collection.
I've only been collecting cast iron for about a year and a half now, but I've learned a lot along the way with the help of a few websites.
http://castironcollector.com (Great website with lots of information for collectors at any level)
http://reddit.com/r/castiron (reddit's cast iron cookware sub, lots of good info)
http://www.youtube.com/user/TheCulinaryFanatic (Jeffrey B. Rogers YouTube videos on using & collecting cast iron. Nice guy, great videos.
One of the things I find fun about collecting anything is being able to use something that's very old in my daily life and it works just like it was new. A cast iron skillet or pot really isn't a complicated thing, so having it work like new isn't a miracle, but I find it fun none the less. The other thing I find fun about collecting is the research. When was it made, how was it made, who made it, what era was it, how much did it cost when new, what kind of people bought it, etc. etc..
Joining a group, or club can help with research. I've been pondering joining one of the two online clubs. Griswold and Cast Iron Cookware Association or "WAGS" the Wagner and Griswold Society but frankly I don't know if either is worth joining. Both of them have their sites locked down so tight that non members can only see the basic forums that have topics that are months/years old. It's like they're scared to let people know what they have, or even give a sneak peek at what you can expect for your $25/yr. - $32yr. dues. I will probably never be able to attend any of their meetings or functions. I'm mostly looking for active forums, and a library for research. If you have any info on which club is better, shoot me an email and explain why. For now, I'll be frequenting the Cast Iron Collector's website forums, as Doug D. is a wealth of knowledge, and I love seeing what other people have found. I also like lending any knowledge I have when I can.
Cast iron collecting can be a fairly cheap hobby, or it can be as expensive as you want it to be. Like collecting many things there are entry level items and there are more rare expensive items that make you re-think whether you really need that item in your collection. A smart collector on a budget can do just as well as a collector with an unlimited budget if you're willing to be patient. Yard sales, flea markets, thrift stores, and even sometimes eBay there are deals to be had. Yard sales, lots of driving. Flea markets, go early, go as often as you can, and go to different ones frequently. Thrift stores, they put out new inventory daily and you aren't the only one looking for a cast iron bargain. The more often you go, the better chance you have of finding something good, or finding anything at all.
Recently I went to my local thrift store and picked up a Griswold "ERIE" No. 8 bulge pot made in 1888 for $10. When I went to pay the guy said some lady almost bought it, but put it back before paying. I was there and bought it. Right place, right time. Same thrift store I picked up two Wagner cast iron skillets and two aluminum Wagner Magnalite sauce pans for less than $20, one skillet was almost new (still had the swirl marks), the other just needed a cleaning, the sauce pans were in great shape. In any collecting endeavor persistence pays. Go early, go often.
That being said, I've overpaid for something I really wanted, and I've vastly underpaid for something I was only half interested in. As in everything, something is only worth what someone is willing to pay for it at that particular time. Patience and persistence will always pay off.
So, you actually want to use that rusty, cruddy skillet you found at a flea market for $9 ?
There are a few ways to deal with different cast iron problems or conditions
Light rust: Soaking in a solution of vinegar & water 50/50 for 1/2 hour or hours/days depending on the amount of rust. This will loosen the rust to the point you can rub it off fairly easily using a scrubby pad. Either the green ones, or the ones I like to use the maroon colored ones. You should be able to pick up either the green or maroon pads at any hardware store or Amazon.
Heavy Rust / Built up, grime: Electrolysis tank. This is a more advanced setup that will require the purchase of a car battery charger, a large plastic tub, some copper wire, a box of Arm & Hammer Super Washing Soda, and possibly some scrap metal if you don't have any lying around you can use. There are quite a few websites and YouTube videos that show you how to build one. Follow the instructions to the letter or you could turn your rare Griswold skillet into a pitted mess and get shocked in the process.
Built up, grime / Paint etc.: Lye bath. This will remove crud, buildup, paint, etc. Won't do a lot for rust. Read up on this before trying to learn as you go. This can be dangerous. Inhalation, skin burns, etc.
Built up, grime / Paint etc.: Oven cleaner spray (Easy-Off). This is lye in a spray can, still dangerous. Read ALL of the warnings on the can. Easier than the lye bath or electrolysis, removes crud/paint, but like the lye bath it doesn't clean rust. There's a great How-To video here...
Stripping a Cast Iron Skillet with Easy-Off Oven Cleaner
For lots more information on cleaning cast iron, see This Page on the Cast Iron Collector website.
Scrubby pads, steel wool, rubber gloves, these are all things you are going to need to get a pot or skillet down to bare metal even after using one of the above methods. After you've done a few you'll know what works for you and what works best. I really like the 3M Scotch-Brite maroon pads. They cut through rust really well but don't harm the metal. I've been using them for years and I love em'. I also use a stainless steel wire brush as well as steel wool sometimes. All of this cleaning, soaking and scrubbing is a lot of work but the end result will be a nice clean base to start your seasoning.
Where do I begin? I guess here. *Deep Breath* Seasoning is a very controversial subject when it comes to cast iron collectors. Crisco, lard, olive oil, flax seed oil, grape seed oil, sunflower oil, avocado oil, canola oil, coconut oil, the list goes on forever.... One oil I cannot recommend is the now famous, often mentioned as the best, the end all be all method, scientifically proven, (But not great Grandmother approved) flaxseed oil method. I've read too many stories of it's failure. Chipping, flaking, the seasoning just going away after a few uses of whatever iron that's been seasoned with it. Sounds good in theory, doesn't seem work in real life. Great Great Grandma didn't have refined flaxseed oil, she had LARD, and it did a damn fine job. If it didn't do you think we've have all this 100+ year old iron to buy right now at our fingertips? Nope!
I will only say one (other) thing about seasoning. I'm sure your great, great, Grandmother/Grandfather didn't even bother. I'm 99% positive that she/he just started using the iron, and it happened naturally. Cooking some bacon, a roast, browning some hamburger, etc etc.. People get all hung up on the "Science" and what oils work best. Honestly, just pick one. If it works for you great. If not try another. Or, just cook in it. I would however recommend that after you've stripped down your iron to bare metal, heat it, and rub it down with something, anything, just to keep it from rusting up on you again until you decide on your method. You can find unlimited methods of seasoning on the internet, I can't positively say which is best but just keep in mind the things available to people 75-100 years ago. Those things will work just fine. *cough* lard, animal fat, bacon, meat, butter.........
Daily use / Cleaning after use.
I won't tell you what oil to use, but you should use oil or butter when cooking in cast iron. I personally use olive oil, grape seed oil, sunflower oil or salted butter, but that's only because I've never really tried anything else. Whenever I cook something I will oil or butter liberally, cook, eat, then clean.
Depending on what kind of mess I made the cleanup will differ. If I cooked some bacon and eggs, and nothing burned or stuck, a wipe down with a paper towel until all the bits and pieces are cleaned out and the pan has a matte finish is all I do. If however, I'm say cooking a burger, and some bits end up sticking, maybe some cheese burned to the pan, my strategy changes. With anything that needs more than a paper towel to clean up I use hot water and a scrubby pad (see above). These look like balls of perforated, bright colored, plastic. Insert hot water, and scrub. That's it. I've never had anything so stuck on that this didn't take care of it. Anything worse, insert water and bring to a boil on stove, let it cool down a bit and then use a scrubber.
Don't be scared, you can't screw it up...
There are quite a few "Rules" that people will repeat over and over again. The do's and don'ts when using cast iron cookware. These are the top two you will read everywhere. "Don't use soap" and "Don't use metal utensils" Both of these are B.S.
First off, soap is so mild nowadays that there is no way it will harm the seasoning on your cast iron. If your skillet or pot is so dirty that you think you need to use soap, go ahead and use it, it won't hurt anything. Rinse thoroughly afterwards, dry then oil with your preferred oil.
Metal utensils. You often hear that you should only use plastic, or wood utensils with your cast iron for fear of scratching off your hard earned seasoning. Whatever... People have been using wrought iron utensils, metal utensils, stainless steel utensils in cast iron since the very beginning. I use only metal utensils, I'm not abusive, I just use them normally and I've never had an issue.
The great thing about cast iron cookware is, if you somehow do manage to screw it up, you just strip it and start over. You don't have to buy another pan, skillet, pot.. Just start over, try again and learn along the way.
What is it? / When was it made? / How much is it worth?
If you're actively collecting cast iron cookware, I'm sure you'd like to know more about the pieces you find and get a general idea of what it's worth. If the pieces you collect are from the late 1800's on, there are two books you need to own. You will often hear them referred to by the color of the book.
These two books cover a lot of ground, but sadly don't cover all of the hundreds of brands that you're likely to run into while out hunting. They do however have great photos, general price guidelines, and are a great help when trying to identify a piece.
For much older pieces there are a few other books you can find via Amazon.com. The most notable one is: Early American Cast Iron Holloware 1645-1900: Pots, Kettles, Teakettles, and Skillets
Wagner_Employee_Newsletters - All in one zip file (26mb)
Individual PDF Files (Everything below is included in the zip file above)
Article in the Sidney Daily News Feb 14th 2009 about the fate of the Wagner Building.
Wagner Building 2009 - Sidney Daily News Page1
Wagner Building 2009 - Sidney Daily News Page2
Apparently they haven't made up their mind yet.
Here is a gallery of photos of the inside of the building from 2012