Indoor Agents
Stone stored indoors features a wide variety of deterioration agents. Knowing these agents and the types of damage they cause can help guide storage and conservation practice. Exposed stone objects indoors should be regularly dusted. Wet washing stone can cause additional damage. Consult a conservator for any severely soiled stone. Wet cleaning without guidance can result in stains moving deeper into the stone, loss of polish, or crystallization of acids, salts, and/or pollutants.
Dirt and Dust build up on exposed flat surfaces and gather in small cracks, nooks, and crannies in the material. These agents will easily stain porous stone, and over time, will deteriorate the structural integrity of stone. Dust and dirt accumulate quickly in areas that feature frequent foot traffic and other high-use areas (exhibits, displays, storage shelves).
Oils, as mentioned elsewhere on the site, can polish, wear, and stain stone surfaces. Most often the result of over-handling, wearing nitrile or latex gloves can limit the amount of oil to stone contact. Easily accessible stone exhibits often experience visitor contact, be aware of visitor contact when using stone artifacts.
Old coatings like waxes, oils, and/or paints may discolor the stone over time, as will some repair mediums. These stains are most often visible on lighter colored stones and stone objects
Relative humidity (RH) that fluctuates too often, is set too high, or too low will also damage stone items in collections. Shifting humidity will cause spalling and can bring reactive agents to stone surfaces. Spalling is the chipping and flaking of surface layer stone. Just like outdoors, high humidity can react with pollutants damaging the stone’s structure. Humidity too low will also damage the structural integrity of stone as rapidly evaporating liquids can damage the surface. Keeping the appropriate humidity is important for stone conservation. Infrared light can change the RH of stone storage and display units.
People are the biggest factors in stone damage. The damages associated with handling and touching are discussed above, but people also accidently and intentionally damage stone objects frequently. Accidental drops and other mishandling events cause breaking, chipping, and cracking. Careless maintenance, repairs, and painting projects can leave stone objects discolored, stained, or damaged. Vandals may also attempt to damage stone displays.
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