How to clean and maintain cast iron lids I have a number of cast iron lids that fit skillets, dutch ovens, etc.  Most have the little cone-shaped spikes on the underside to collect and return moisture to the food.

I have no issues cleaning and maintaining my cast iron pans and pots, but I find the lids are prone to specific problems.  Here are the two main ones:

(1) When simmering or baking with the lid on (or partly on), the underside of the lid gets exposed to a lot of water vapor which then condenses.  The underside is therefore "attacked" by more excess moisture than any other part of my pots or pans.  Over time, this tends to degrade the seasoning and can more quickly lead to rusting.  With periodic oiling and reheating after cooking, I find that I really never need to do a complete re-seasoning of a pan (unless it gets damaged in some way).  But seasoning on lids seems to degrade a lot faster, and it's next to impossible to do stovetop "maintenance seasonings" with a little oil because of the shape of the lids.

(2) When cooking over high heat in a skillet, I sometimes want to put the lid on.  For example, one method I like to cook a cheap thick steak is to sear over high heat on both sides, and then turn off the heat and put the lid on to finish cooking (which is easier and simpler than heating up an oven to finish it).  Anyhow, if the pan is hot enough, a significant amount of grease will rise in the closed pan and condense on the lid.  The residue is difficult and annoying to clean because of the spikes on the lid.  Another area that often gets build-up of grease is the small lip right on the edge of the underside of the lid.  Neither the spiky area nor the lip lends itself well to scrubbing with salt or wiping with paper towels, which I commonly use to take care of the pans and pots.  In just a few uses over relatively high heat, the grease will build up, leaving behind sections that are gummy and others that are hard to scrape off -- and it seems like it also can trap moisture sometimes that contributes even more to the problem mentioned above with degraded seasoning and even rusting.  Unless I soak it in a sink with hot water and a lot of soap, it's very difficult to keep clean, and that will also degrade the seasoning more quickly.

In many cases, I've just given up and will use an ill-fitting random lid on cast iron rather than the traditional cast iron lids.  But given that people can buy lids like this, there must be ways to maintain them without gummy grease build-up or spotty seasoning.

Is there a way to avoid or lessen these problems or to solve them in a straightforward way?
We use kosher salt to clean (still-warm) cast-iron by pouring in a handful then rubbing around with a (usually paper) towel. The kosher salt grain size is just right to be an abrasive for removing excess grease and other food particles, and you don't have to worry about it melting. Then a wash with hot water and a little soap to complete the washing, followed by a rinse. To avoid rust, we dry the pan by putting it on the stove, high flame, until the water has evaporated.
We have to re-season the pan every once in a while (once or twice a year), but this method has worked well for us.