I am a bit confused how to “unrust”. All the patterns I thought of don’t work as I cant refresh the spoilage if it’s not yet rusted. It would be easy to filter beforehand but there is the inevitable race condition that stuff could spoil after the filter and deadlock my machines.

What are good patterns? Or is there a way to reset spoilage for non rusted metal?

I can help but first out of interest, have you played Gleba?

No, have not been at Gleba yet.

As you may have heard, Gleba is no joke! This is one of the contributing factors.

One approach is to put an inserter at the end of each iron belt with a filter set to only pick up rusty items.