I am relpying to Sue Maltby's request for information on this topic and I am
posting it to the list for those who might enjoy techno-trivia.

What came to be known as the Bower-Barff Process is actually a modification
of the ancient processes of forming stable oxidation films on metals by the
use of thermal and reduction/oxidation athmospheres.  Charcoal blueing of gun
components, springs, and fine instuments is an example of this process.

What came to be known as the Bower-Barff Rustless Process was invented by
Professor Fredrick S. Barff of Kilburn, England, who published his results in
1877.  The process was subsequently modified by George Bower who modified
Barff's process to an industrial scale.

In the Bower-Barff Process cleaned iron or steel bars were heated to a bright
red color (1700 F) in special furnaces where super-heated steam would be
inroduced.  This produced a "skin" of stable magnetite (Fe3O4) and some
Wustite (FeO) oxides which cocooned the iron, making it relatively impervious
to rapid oxidation (rusting).  Later improvements to the process utilized
hydrogen and carbon monoxide athmospheres which allowed for complete
conversion of the ferrous surface to magnetite.  This meant that the process
could be performed on a large industrial scale with consistent results and
the Bower-Barff Process was patented in 1881.  After it's widespread adoption
for use in architectural ironwork the process came to be know as "Barffing".

        "Barffing is so called from the name of its discoverer;
          and its purpose is to render the surface of metallic
          article treated, resistant to acids and impervious to
          humid oxidation.  Iron and steel that have been properly
          Barffed will not rust.  The process belongs in no sense
          to the chemical laboratory, and it requires no particular
          scientific knowledge or technical skill for its success.
          Highly polished work retains its finish after the process,
          although the treatment changes the shinning polish
          to a dark slate color.  But working parts, such as sliding
          and rubbing surfaces, retain their smoothness, and
          work as freely as before the process; plugs, valves,
          and stems for cocks, gates, and faucets, for instance,
          working just as smoothly  as though they had not been
          Barffed."
                                 -Brannt, W.T., ED.  The Metal Workers
                                  Handy-Book of Receipts and Processes, 1896,

                                  pps. 297-298 .

For those who want to read about this process in-depth, along with
descriptions of other nineteenth century architectural metal finishes which
were investigated during the restoration/conservation of the Rookery in
Chicago, Ill., USA,
I highly recommend the following paper:

"Conservation of Architectural Metalwork: Historical Approaches to the
Surface Treatment of Iron"  by Frank G. Matero, in Ancient & Historic Metals:
conservation and scientific research,  David Scott, Jerry Podany, Brian B.
Considine, Editors,  The Getty Conservation Insititute, 1994, ISBN:
0-89236-231-6  (pbk.)

This book also contains papers which range from the restoration of the
monument to Marcus Aurelius to the use of gold foil, strip, and wire in the
iron age of Southern Africa. It is a must for conservators and curators who
work with ancient and historic metals collections.

Dave

David Harvey
Conservator of Metals & Arms
Colonial Williamsburg Foundation
P.O. Box 1776
Williamsburg, VA   23187-1776 USA
voice:     804-220-7039
e-mail:  [log in to unmask]