Iron rusting and breakage upon interaction.

I propose adding a rusting mechanic for iron. Just like with copper, there would be four stages.

The first stage is standard iron.
The second stage looks the same but has a different texture, signaling to the player that unless it is cleaned, mechanisms will stop working at the next stage.
Starting at the third stage, iron mechanisms no longer function correctly; there is a 50% chance they will fail to activate.
At the fourth stage, they will not open at all.

I also propose adding an iron grate block, similar to the copper grate block.
At stages 1 and 2, the block remains sturdy.
At stage 3, interacting with the block (clicking, hitting, or standing on it) carries a 50% chance of it breaking.
At stage 4, interacting with it results in it breaking 100% of the time.

When broken, it drops iron bars, which can be crafted back into a grate block.

Rusty chains should also be added; these would likewise break upon interaction.

However, if waxed copper or iron blocks are created, they will not break at all, even at stage 4. The same applies to mechanisms—they will continue to open without issue.

In other words, waxed variants serve purely as decorative elements, whereas the others incorporate the breakage mechanic.