Tom,

I would suggest that you acquire several teflon "policemen" from one of the archival/conservation catalogs.  They have beveled ends and work great in safely removing accretions of all types.  If you cannot find one to buy you can fashion one of your own from a teflon spatula, or even a teflon rod 1" diameter.  Use the teflon to scrape off as much of the droppings as possible.  Then, I would suggest using a power washer to remove any remnants of the accretions.

Bird droppings are a serious problem to historic buildings, architecture, and sculpture.  I have heard of everything being tried from inflatable owls, cayene pepper, to a bird-drug that zonks the pidgeons into la-la land.  So far, I have not heard of anything that seems to consistently work.

Cor-Ten Steel does actually corrode if areas are hidden from the sun and do not dry.  This is a big engineering problem on bridges and highway overpass structures. Cor-Ten sculptures can suffer severe corrosion on their interiors from condensation if drainage "weep" holes were not put into the sculpture by the artist/fabricators.  Most likely the bird droppings will be on the most exposed areas of the sculpture that receive adequate sunlight.  If not, then you will need to immediately dry the areas after washing by using either forced hot-air or acetone applied locally.  If you use a chemical follow all safety instructions on the Material Safety Data Sheet and use only the minimal amount necessary.

Other than this, I would not suggest that you go any further yourself until you contact a conservator who is familiar with the treatment of outdoor sculpture.

Corrosion engineers are quite knowledgeable about corrosion processes but are not often concerned with the principles of object and art preservation; such as reversibility of treatment, stabilization and minimum intervention, and maintaining the physical and artistic integrity of an object/artifact.

For more information on conservation and to find helpful information and resources go the AIC web site at:
http://palimpsest.stanford.edu/aic/

Cheers,
Dave

David Harvey
Associate conservator,
Metals & Arms
The Colonial Williamsburg Foundation
P.O. Box 1776
Williamsburg, Virginia  23187-1776  USA
Voice:    757-220-7039
E-Mail:   [log in to unmask]

-----Original Message-----
From:   Museum discussion list  On Behalf Of Tom Hunter
Sent:   Monday, August 24, 1998 6:05 PM
To:     [log in to unmask]
Subject:        Cleaning of outdoor sculptures.

        Does anyone out there have any suggestions or experience with the cleaning
or removal of bird droppings from Atmospheric Corrosion Resistant Steel
(Corten) sculptures. We have a number of large pieces here on campus which
are constructed of this material and seem to be the preferred depository of
said bird droppings. Any suggestions or ideas would be greatly appreciated.

                                                        Thank you,
                                                        Tom.
--
Tom Hunter, Collections Assistant
Museums and Collections Services
University of Alberta
Edmonton, Alberta, Canada
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