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?

I cross posted Barbara's query on Bullamanka-Pinheads, a listserv
oriented towards architectural conservation, and Steve Stokowski
<crushstone<-at->aol<.>com made the piquant remarks below (reproduced with
permission)

   "Apparently she doesn't know as much as she thinks she  knows.
    Just why shouldn't salt be used on marble steps? No good reason
    at all, she may have half read and retained less a newspaper
    article about salt use on roads. The issue with salt, and I am
    specifically talking about NaCl, is  that it increases the rate
    of corrosion of steel, specifically steel embedded  in concrete.

   "Salt is one of the best deicers available.  Some of the other
    chemicals, such as MgCl, K Acetate, and Na Acetate, react with
    the minerals in  concrete and cause different, and in all
    respects, more serious deterioration that requires removal of
    all of the concrete.

   "So, unless the marble steps are pinned together with ferrous
    pins, she should go ahead and use NaCl to deice the
    steps--before a citizen falls and breaks a hip, and then owns
    the  building. Or she falls herself, and the hospital owns the
    building.

    Steve Stokowski"

Another Bullamanka-Pinheads subscriber said that alcohol is an
excellent de-icer.

Christopher Gray


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                  Conservation DistList Instance 23:31
                 Distributed: Monday, February 22, 2010
                       Message Id: cdl-23-31-003
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