Clearing snow and ice from marble steps

Barbara Appelbaum <aandh [at] mindspring__com> writes

>A client of ours has asked about the problem of clearing snow and
>ice from marble steps.  She knows that salt should not be used.  Is
>it possible to apply coatings in advance that will mitigate the
>possible effects of salt, or is there something else--ash or sand,
>perhaps--that is not harmful to marble?

While products to seal porous marble, fissures and mortar joints
would provide some protection against salt penetration they would
certainly not completely mitigate the effects of salt.  I would
investigate the use of urea which is one of the most common de-icing
compounds used in corrosion sensitive environments (by, for example,
airports).  I believe that it sublimes at normal temperatures
(partly through decomposition) which would be desirable from a
reversibility view. The use of a grade more pure than fertilizer
grade would be required.  This is a possibility and may reduce
overall damage rate by reducing the need for scraping but I would
not recommend its use on a heritage property without first doing
some investigation of possible problems.

Robert Waller, PhD, CAPC,
FIIC Protect Heritage Corp.
622 Simoneau Way
Ottawa ON  K4A 1P4
613-830-1883


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                  Conservation DistList Instance 23:30
                Distributed: Tuesday, February 16, 2010
                       Message Id: cdl-23-30-003
                                  ***