Molly McGath, NCPTT summer intern, is studying interactions between air pollution and limestone treated with commonly used chemical stone strengtheners, Conservare OH100 and Hydroxylating Conversion Treatment (HCT), both distributed by Prosoco, Inc. Her experiments will help preservationists better understand the long-term strengths and weaknesses of using chemical treatments on cultural stone. She is looking at whether sulfur dioxide deposited on stone under dry conditions chemically binds and changes the stone to gypsum or slowly desorbs from the stone over time.

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5 Responses to Interactions Between Air Pollution and Limestone

  1. gayle mcadams says:

    has this stone strenthener ever been uused on puddingstone/granite and not soft limestone. any interaction with granite? Any health issues?

    • To my knowledge, consolidation treatments have not granites. Conservare OH100 is an alkoxysilane and may bond with granites. HCT is an inorganic stone strengthener which may not work well on granites, particularly those with iron inclusions. I would use caution applying any stone strengthener to granites.

  2. Payal Vora says:

    Hi Mary, I am working on analysing the deleterious effects on a limestone building in TX, that was treated with HCT. Based on the random deterioration of limestone blocks (spalling and orange, presumably ferrous discoloration), combined with unsupervised application of HCT, I suspect that the treatment exacerbated and expedited deterioration in the limestone. Would you be willing to share some of your research or publications as references for my work?

    Thank you!

  3. adi ben zvi says:

    a highrise(34 floors) was cladded with chisled limestone near the sea shore.we are looking to protect it from salt damages.do you think that a joint treatment wth HCT+OH-100 will do?
    thank you
    adi

    • Following the American Institute for Conservation’s Code of Ethics and Guidelines for Practice, I cannot recommend a treatment for a site without careful examination of the cultural property. I am unsure of the level of damages observed on the building. I am not familiar with the justification for a joint treatment on the structure. If you would like to discuss your project more thoroughly with me, you are welcome to call our office.

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