Originally Posted by Skyman
Do not sandblast or use sandpaper on your Dutch Oven. Rust is easy to remove. Clean it, coat it good with veg oil. Turn it upside down on a grill and let it cook at 350 for an hour. Let it cool a bit, oil it again, and put it on the grill again upside down for another hour. It needs to smoke. I repeat this process a few times to get it seasoned. If done right, you will never need to do this again. After this process, don't use any detergents in the oven when cleaning. Only water and heat.
I've seen where one person recommended not sand blasting because it could make an uneven surface. Look at a cast iron skillet and see how it was 'sanded' smooth on the bottom inside vs the outside. Those skillets require the same care that a dutch oven does and most of them were smoothed out by some type of abrasive disk by the manufacturer.
After other methods of dealing with the rust do not bring your DO close to as smooth as your best cast iron skillet, you might want to sand. Take care not to overheat the oven during this 'sanding'.
Then super clean it.
Then start the seasoning processes
A consideration for an affordable multiple option Dutch Oven is getting a Lodge brand 3 qt (Chicken Fryer) skillet with shallow skillet lid. These are on eBay for $38 including shipping and a limited lifetime warranty, (If you drop the oven and break it its on your dime). This gives you a DO or two cast iron skillets.
They come pre-seasoned with Lodge's special vegetable oil high temp seasoning. Remember, that is just the first seasoning done right. I hear Camp Chef also does a pre-seasoning.
The inverted skillet top will not hold coals as well as a lid with lip. There are no legs on the bottom skillet so you'll need to set up 3-4 rocks with the coals in between or pack a steel wire trivet
for that support.
Don't put a cast iron appliance on a propane or similar stove without gently bringing the iron up in temperature to avoid cracking it. Cast Iron cracks cannot be repaired. If your iron sat outside in 35 degree air overnight it will be 35 degrees.