Before we prep for what is known as seasoning I should say this is perhaps one of the most misunderstood parts of cast iron cookware, this is the place where most fail, a lack of a proper seasoning is where the majority of problems people have with cast iron come from. A true seasoning on our cookware is a thin layer of carbonized/polymerized edible oils/fats that have had all the volatile substances burned off, leaving only the carbon behind and forming long chain molecules. If that sounds complicated, it?s not, it is easy to do and I will come back to that simple process in a bit, but first we need to have our cookware prepared to accept the seasoning.
Preparing Cast Iron for Seasoning
Our cookware we need to get ready to use can be newly made or it can be new to us, but used by someone else in the past, or even something we have owned for a while, but are not happy with how it works due to being poorly seasoned.
Most of the new cast iron sold today is what is called pre-seasoned, it is the easiest to work with, wash it with soap and water, dry it, add some oil, get the oil hot, add a couple eggs and then fry them, if it works fine, it is good to go, it is now ready for cleaning and care, if not, the factory did not get it seasoned well, but I?ll tell you how to fix that in a bit, start a pile for cast iron needing seasoned.
I will note before going further that when you get cast iron clean and down to the bare metal and dried, you will sometimes have a bit of red powdery rust on the surface, that is fine, no harm, no foul, the seasoning process will take care of it.
New but not pre-seasoned will have some sort of oil or wax to prevent it from rusting, often these can be removed with just soap, hot water and a good scrub pad, rinse well and dry it over the stove burner to remove all the moisture, look to see if it has that nice grey color of bare iron, you may have that fine layer of red oxide known as rust, but that is no problem, set the piece aside in the pile of needing seasoned and we?ll get to it after we get our used pieces ready.
Used cast iron often causes the most controversy as to how to get it ready for use, many say if the piece looks good and is well seasoned just use it, I don?t, I prefer to strip it and re-season it, others may not, it?s just what I prefer. As for the method used, it?s like the old saying, ?and that is when the fight began.? There are several methods; all will work if they are used properly, they all can cause trouble if used improperly, and the methods I know of can be heat, chemical, mechanical, electrolysis or even a combination of all of them. Before using any of these methods, like new pieces, I like to wash the piece with hot soap, water and the scrub pad to remove all the oils.
To me, the easiest is heat, although when it is discussed it seems to be the most controversial method with many saying you will ruin the piece, well you can overheat it and/or heat it very unevenly and you can warp it, you can crack it or form an oxide layer often called red scale that makes it hard to season.(the red scale can be removed by mechanical methods because it?s just on the surface, hand sand with 120 -150 grit sandpaper till clean and shiny and don?t do it again.)
Use heat in a sensible manner and there is no problem, but I will add this disclaimer I would hesitate using it on a really old valuable piece, if you do over heat it and warp or crack it, then that piece is lost forever because they are no longer made, practice on lesser pieces.
As for cleaning it with heat, I most often just take the piece or pieces with me to one of my camps and in the evening when the cooking is done (and before it gets dark, the time people want to sit around the fire) I just let the fire burn down to low coals spread out evenly and place the piece or pieces on top of the coals and let the crud burn off, removing it when clean and before the piece gets that red glow to it. I then set the piece aside to cool then take it home and finish it most times.
Others use a self-cleaning oven, very simple and easy, it might smoke the house up some, I have used it in the past but no longer have that type of stove. Others use an outside gas grill and that keeps the smoke out of the house, no matter what the method of providing heat, the goal is to clean it only and by not turning it red hot or beyond and heating it evenly it has worked fine for me for a lot of years. After it has cooled, I put it in the sink (or if too big for the sink I use our bathtub) and use warm water and dish soap on it and scrub it up well removing all the burnt material with a stainless steel pot scrubber, then dry it on the stove and it is ready for our pile that needs seasoned.
Chemical methods most often involve either an alkaline substance or an acid substance to remove rust and built up layers, the alkaline substance most often being lye (sodium hydroxide or potassium hydroxide solution) it is often used in drain cleaners and oven cleaners, and it is caustic so some care has to be used with it. One method often used is to simply buy spray on oven cleaner and to use it on the piece then put it in a garbage bag for several hours or even several days, rinse, scrub well with soap and water and see if all residue has been removed, if not, recoat and let is soak again.
The lye method involves adding 1 pound of lye to 5 gallons of water (make sure the lye is added to the water and not the water to the lye) and soaking the cast iron in this, the cast iron can stay in it for a long period without harm. One must remember that lye is caustic and one must keep it from contacting the skin and is best done in an area where children and pets can?t come in contact with it.
Lye does a good job of removing the old build up, but is not that good for removing rust, many recommend neutralizing the lye with vinegar after cleaning, but rinsing well should remove all the lye, one can do this to make yourself feel good, if there is lye left, there will be a bit of bubbling when the vinegar is added from the Carbon dioxide being formed as the lye is neutralized.
When using the acid method one of three acids are used, one being acetic acid the acid found in vinegar, citric acid found in citric fruits as well as molasses and phosphoric acid, which is often used as metal prep for cleaning new metal before painting, but is also used in soda pop to give it that bite, Coca Cola having what is said to be the highest percent.
Vinegar can be used straight or diluted, and any type can be used, I use white vinegar because most times it?s cheaper and I use the cheap store brand. Most vinegar is about 5% acidity no matter the brand. The method recommended by many for a vinegar bath is a non-metal container big enough for the piece or pieces and fill it with ? vinegar/1/2 water and submerge the piece in and let it soak for a few hours, remove it from the bath, scrub as before and resoak if needed. I myself just use our bath tub since we also have a shower, it is not unusual to have cast iron being cleaned in my tub and it works great.
The citric acid method seems to most often use molasses as a cheap source of this acid, the recommended amount being 1 part molasses to 9 parts water, this method is said to take 2-4 weeks by those who use it and the animal supplement type found at farm stores is the cheapest. I myself have never tried this, but I?m relating it because some seem to like the method, to me it?s too slow.
The phosphoric acid is perhaps best used as Coca-Cola I have used this in the past as a cleaner for small steel and iron parts, having also used the higher strength metal prep in the past; I don?t recommend it metal prep for home use. The Coca-Cola works well to remove rust but making a vinegar bath although perhaps slower, is cheaper than the Coca-Cola by far.
Mechanical can be as simple as a good scrub pad, sand paper, steel wool or other similar items, or it can involve using compressed air to force an abrasive material under pressure, this is called blasting, the abrasive can bee sand, steel shot, ground corn cobs or walnut shell or baking soda. The baking soda uses the finest grit and is what I recommend if having pieces blasted. The other can leave a very rough surface, depending on the coarseness of the grit, the pressure it?s blasted as well as the skill of the operator using the equipment. Soda blasting is used for a lot of delicate restoration work so it will be fine on cast iron although it will cost more than the do it yourself methods.
The electrolysis method uses an electrical current to remove the rust, it is a process similar to plating with chrome or other metals, but the process is reversed. The iron from the rust is deposited on another iron rod rather than the metal from a rod being deposited on the piece as in plating; in fact this method is used in restoration work to remove plating before prepping and replating.
The rusty iron and the so called sacrificial rod are immersed in a solution of washing soda (Sodium carbonate) available at most any grocery store along with the laundry detergent at a ratio of 1-2 tablespoons per gallon of water. The sacrificial rod and the cast iron piece are hung in a non-metallic container so they are fully immersed. A manual (not automatic) battery charger is hooked up with the negative (black) to the piece to be cleaned and the positive (red) to the sacrificial rod and the current turned on, the rust them flows to the sacrificial rod and the whole process only takes a few hours. A battery can be added to the circuit if the battery charger is not a manual one, the current to the tank needs to come from the battery and the battery charger keeps the battery from being drained. (As anytime working around water and electricity one needs to be very careful, the washing soda is what is called an electrolyte and makes the water more conductive to electricity.)
As before, clean the piece with soap, water and a scrub pad, dry with heat and examine to see if you have reached the bare iron. If it is done, also add it to our pile. The next page will tell us how to do that.