How do you prevent rust on metal lids during long-term food storage?

Hi everyone,
For people who preserve or store food for a long time, how do you prevent rust on metal lids, jar lids, rings, or cans?
I’m especially interested in storage in humid conditions or places where temperature changes may cause condensation.
Possible causes I’m thinking about include:
- High humidity
- Condensation
- Salt or acidic food residue
- Scratches on the lid coating
- Damaged coating during handling
- Storing jars with rings on
- Poor airflow
- Long storage time
What methods have worked best for you?
Do you use dry shelves, plastic bins, moisture absorbers, regular inspection, climate-controlled storage, or another method?
I’m mainly interested in practical experience with rust prevention, storage conditions, and lid durability.

Emma, welcome to the forum.

I have never had rust on lids for things like flour or rice.

My problem has been things that have been canned so I don't have an answer.

the method that works for me is to float a thin layer of cooking oil on the top of the preserve - usually chutney, pickled capers etc.  That is acid containing preserves.  Recently found a jar of peach chutney [no oil used] at the back of the cupboard where then lid was almost eaten through and appeared to be 1 atom of rust thick.  I have also been known to use this method on jams where the plastic lids are known not to seal completely - easily poured off when jar is opened.  I always use olive oil. The storage is a dry cupboard, but where we live is low humidity most of the time.

I frankly haven't found a solution, and it's a big problem, especially with acidic contents. If anything is not sealed (Indian pickle, for example), I use a plastic lid. I tried normal lids with wax paper or plastic wrap or bags and they still rusted. Things that have to be sealed, I just buy new lids and as soon as they show any signs of being not 100% I switch them out. I hate it but I don't have a better solution.

As for rusting on the outside, I find it to only be a problem with certain kinds of lids. If I can avoid them, I don't have a rust problem (and I live in humidity central). I do keep a humidity trapper in the cabinet where I store my canned goods.

Thanks everyone for sharing your experience.
Judging from the comments, keeping items dry, avoiding humidity, and regularly inspecting lids and can bodies are effective ways to reduce rusting. Apart from storage conditions, condensation during transit, damaged packaging, scratches on lids, and residues of acidic or salty food can also accelerate corrosion on metal surfaces.
I came across [an article explaining the causes of rust stains or discoloration on tinplate after transportation and storage](https://zenjoypackaging.com/en/news/why-rust-appears-on-tinplate-after-arrival-and-how-to-reduce-the-risk). It covers factors such as moisture, temperature fluctuations, packaging protection and warehouse conditions, which are highly relevant to this discussion.
I’d like to ask everyone: If there is only slight surface rust without obvious pitting, bulging, leakage or seam defects, how do you normally judge whether the lid or can can still be used? For food cans, is it generally recommended to discard them directly once severe rust, bulging or leakage occurs?

I don't do enough canning to know how accurate this is.  

The advise i was given
1. Always allow ample head space inside the jar.
2. When jar cooled from canning, remove ring, clean ring and outside of jar.  Let dry overnight before returning ring
3. Avoid tilting the food so it touches the lid.
4. For this person, most of the risk was in using the jars and keeping in fridge, so choosing jars for one session worth of food (meal, week, whatever) was preferred.

I think there must be more to it than that.  The storage was a former spare bedroom in the basement that was surprisingly cold and dry for that climate.  She was very aware of temperature change when moving jars in and out.