Restoration of stone objects
OwnerMaurizio Pouchain, Ludovico Medolago Albaniinventors
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Abstract
The restoration of monuments and other objects made of stone is described. The process is carried out by immersing the stone object in deionized water in order to dissolve the calcium sulfate contamination present on the deteriorated stone which is caused by the pollutants present in air, then circulating the water containing the dissolved calcium sulfate through an ion exchange resin which can selectively trap the sulfate and release calcium hydroxide into the solution, followed by exposure to carbon dioxide under controlled conditions in order to thereby reprecipitate the calcium ions on the stone object as the carbonate in the calcite crystalline form.
Claims4
A process for the restoration of a stone monument or stone object contaiminated by calcium sulfate comprising immersing the object in deionized water so as to dissolve the calcium sulfate in solution, then circulating the water containing the dissolved calcium sulfate through an ion exchange resin which selectively traps the sulfate ion and releases calcium hydroxide into the solution according to the equation:
- CaSO.sub.4 .revreaction.Ca.sup.++ +SO.sub.4.sup.-- .fwdarw.ion exchange resin.fwdarw.Ca.sup.++ +2OH.sup.-
- and then circulating the ion-exchanged water in a circulatory system back into contact with the monument or object and subsequently exposing the monument or object to carbon dioxide under controlled conditions sufficient to cause reprecipitation of the calcium ion on the monument or object as the carbonate in calcite crystalline form.
Dependencies are inferred from the claim text.