It’s spring again and some of us will tend to small projects around the house. Like mowing the lawn, weeding the garden, painting the blinds or the entry iron gates. That viciously develop rust in the more inadequate and hard to reach places.
Rust is the common name given to the alteration of iron-based metals. It is more or less red, more or less powdery and always a bad news.
It is the visible sign metal has been exposed to exterior assaults and that it is transforming itself. If nothing is done, rust will slowly but surely consummate the whole metal and render the object a mere wreckage.
Oxidation and corrosion mechanisms are complex and different depending on metals and their composition. Yet, they do have a common origin : the only inalterable iron is the iron ore. Be there a stable mix of elements completely useless to make anything but ugly paperweights.
In order to be used, the ore has to be processed. And this is where the oxidation process begins also…
Very annoyed by this whole processing business, iron will try to go back to its stable ore form one way or another, using for that purpose every elements it can be in contact with including but not limited to : rain water and humidity. So much for your iron gates.
Rust will always win : regular maintenance by applying protection from outside elements (i.e. painting metal) or keeping metal based items in a dry environment are your only options.
Museum collections are no exceptions : time eventually turns solid iron into reddish powder. One can but only delay a process that will take every opportunities it is given to go on.
Contextual alterations are usually treated when the piece first enters the museum and gives good results, provided the environment is stable from here on in. Most of the time, those treatments include mechanical rust-removal component. That is to say « very gently scratching the piece with a scalpel to expose rust-free metal » before chemical stabilization and protection may occur.
This long (long long long) and thorough process allows certain discoveries like bringing back a mark or a hallmark from the rust coating. And it’s a spirit lifter after days of endless scratching !