Rust

"Archaeologist, Chemical Engineer Unite in a War on Rust"
By John Gagnon
May 2, 2012

<URL:http://www.mtu.edu/news/stories/2012/may/story67592.html>

Archaeologist Timothy Scarlett with a pulley stand at the Quincy
Mine, near Hancock. He's searching for a simple way to keep such
iron artifacts from rusting away.

Industrial archaeology studies the past and seeks to enshrine it as
heritage.  In that undertaking, archaeologist Tim Scarlett, of
Michigan Technological University's Department of Social Sciences,
has his eyes focused far into the future: he wants an ironclad way
to preserve artifacts in order "to curate into perpetuity."

Scarlett's world is filled with discarded items on industrial sites,
where he unearths iron: nails, forge and blacksmith wastes, tools,
and scrap iron all artifacts whose very nature is to corrode and
break down, a process that spells ruin for preservationists.

Scarlett and chemical engineering professor Gerard Caneba have
received $25,000 from the National Park Service to research methods
to combat rust, which is iron's ill fortune.

   "Iron is unhappy to be alone," Scarlett says. "It's unstable.
    It's much happier when combined with other atoms in chemical
    compounds. It particularly likes to bond with oxygen."

Under the influence of oxygen, iron becomes ferric oxide or ferrous
hydroxide what we know as rust or corrosion.

Given sufficient time, oxygen and water, any iron mass will
eventually degrade and convert entirely to rust. Acids and salts in
moist soil accelerate the process.

Currently, corrosion impedes efforts to preserve cast iron material.
Put partly corroded nails in a zip-lock bag, store them awhile, open
the bag years later, and end find "lumps of rust powder," Scarlett
says. He wants to curtail that natural process. "Stopping corrosion
is paramount," he says. "We want to preserve every little bit of
data and artifacts in the long term."

This is more challenging than it seems, Scarlett adds, because
museum curators are a fussy bunch. "Imagine a client who wants you
to take their rusty products and stop them from corroding any
further but you can't change the material structure, the chemical
properties, or the appearance. And your treatment can't degrade over
time, must be inexpensive, quick, and safe. Oh, yes, and it should
be reversible so we can undo whatever we do now.  Museums are full
of materials that were 'cleaned' and 'repaired' using new tools and
processes that failed decades or centuries later. Ethical
conservation is like medicine.  'Do no harm' is the first
principle."

Current remedies to combat corrosion are low-tech, slow and
problematic. They include baking the artifact to dry it out, which
often doesn't reach the moisture in small fissures and pores; and
electrolysis removing corrosion layers while applying a plating,
similar to chrome on steel, which Scarlett says is intrusive and
impractical.  "It's like amputating an arm for a hangnail," he says.
"It's too much treatment, especially for delicate objects."

So Scarlett is teaming up with Caneba, the director of Tech's Center
for Environmentally Benign Functional Materials, to investigate two
new methods to combat rust: using highly pressurized carbon dioxide
to displace water in pores and fissures, which should discourage
iron artifacts from degrading, and impregnating the objects with a
coating of benign polymers that would prevent the absorption of
water.

The National Center for Preservation Technology and Training, a unit
of the National Park Service, is supporting this one-year project.
Scarlett and Caneba will build on it by involving a broader,
collaborative team of Tech faculty that will seek more funding to
implement full-scale work at an industrial heritage site. Meanwhile,
the two researchers will challenge students to design treatments for
objects as small as a chisel and as large as a mine hoist.

Scarlett has been at Tech since 2001. He teaches people about
artifacts, buildings, or sites. "Something in human culture makes us
interested in the past," he says. "We have intense interest in
history and archaeology. They can make us who we are, so they are
important to understand and preserve. The past informs the future.

   Michigan Technological University (<URL:http://www.mtu.edu>) is a
   leading public research university developing new technologies
   and preparing students to create the future for a prosperous and
   sustainable world. Michigan Tech offers more than 130
   undergraduate and graduate degree programs in engineering; forest
   resources; computing; technology; business; economics; natural,
   physical and environmental sciences; arts; humanities; and social
   sciences


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                  Conservation DistList Instance 25:49
                   Distributed: Saturday, May 5, 2012
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