Originally Posted by Dutch
Aaron, are you asking about the bottom of the pan that sits on the fire, or the interior bottom of the pan?
If it's the bottom that sits on the fire, don't worry about it. Just wipe it down with veg. oil while it's still hot (usually after you've put it on the burner to heat up the pan and evaporate any water left in the pores of the iron.
If it's on the interior, you can burn off the existing seasoning and start over again. The best way I've found to burn off the seasoning is to place the D.O. upside down on a charcoal or a propane grill over a hot fire and close the top and let the heat do it's magic. You might have to use a brass brush and knock off any carbon that's was left behind (remnants of cooked on foods). Allow the cast iron to cool down a bit and then give the cast iron a good coating of vegetable oil or vegetable shortening. Place the cast iron back on the grill-again bottom side up- and close the cover. If you are using a propane grill try and keep the temps between 400-450° F. Let the oil bake into the cast iron 1 1/2 to 2 hours. It will take several seasoning sessions to obtain that glossy black no-stick surface, Your first session will leave your cast iron with a green/gray color on it-subsequent seasonings will get it to the black you're looking for.
Some may tell you to oil up the affected area in place in to a 400° oven for an hour or so-the problem that I've encountered is if the over all seasoning is of a poor quality, the existing seasoning may burn off and then you'll be starting over at square #1.
This is about the best and truest advice you are going to get anywhere. Dutch knows his stuff!
My two cent is after this, make a few pots of braised beef roasts and chicken over the next month or two. Don't skimp on the butter, flour or potatoes. Definitely stay away from any tomatoes or acid vegetables.
Once cooled, just rinse your DO under warm-to-hot water and scrape off any bits with your thumbnail or soft sponge. Anything harder and you will scrape off your seasoning. No need for soaps, though a teaspoon of dish detergent in a gallon of water is the most you will ever need. Just wipe and let air dry; recommend against soaps unless you really need them, then you should start over.
After drying, wipe down with peanut oil and a paper towel (on the inside, of lid and container) and put away. You may need to re-do this at first, before cooking in it again if the seasonng has really worn off or not there at all.
Once seasoned, they beat a nonstick super-duper-modern pan anyday. Plus you can hand them down to your kids. You got yours from your grandparent's right?.............