Iron corrosion in leather boot

I am working out some treatment options for a leather boot found
under the site of a small heritage centre during construction.  The
centre would like to display it (aesthetically 'as is' so no major
restoration or repair necessary) early next year as part of a
display on the history of the centre.  However the sole of the boot,
particularly near the heel and toe is significantly deteriorated and
has the appearance of advanced iron corrosion/rust.  There are what
looks like old nails or tacks and it is possible that the boot was a
steel reinforced construction worker's boot.  This area is
continuing to corrode and is extremely friable.  The centre want
only to prevent further corrosion so it can be displayed without
crumbling and leaving corrosion product in the bottom of the display
case.

While research suggests that immersion to remove chloride ions and
raise pH to prevent further corrosion is often recommended for
archaeological iron in advanced stages of corrosion, the presence of
the leather means excess moisture should be avoided.

Are there other methods people have had success with in such
situations? I am considering attempting localised treatment of the
corroded areas with sodium hydroxide, sodium carbonate or sodium
percarbonate solution and consolidation with Paraloid B72 in ethanol
but am unclear at this point if my ideas have merit.  I do have
multiple samples on which I can test treatment options
(destructively if necessary: the client has no desire to re-adhere
any crumbling fragments, just to prevent their continued
de-attachment.  Any ideas welcome.

Andrew Hawley
Private Conservator


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                  Conservation DistList Instance 27:25
                 Distributed: Sunday, December 15, 2013
                       Message Id: cdl-27-25-012
                                  ***