Contributors: Amy Morse
Tiny cracks and hairline fractures that form in glass and feel wet or even greasy to the touch.
Synonyms in English
Crizzling happens as the result of too little stabilizer or too much of an alkali in the glass’ recipe. When the glass is exposed to a relative humidity that is too low (below 40% RH), the surface will lose moisture. If the RH is too high (above 55 %), it will “weep”. This moisture is pulled out of the sub-layers of glass in an environment with over 50 percent relative humidity and condenses on the surface of the object. Typically, crizzling is found in glass made before the 19th century and after the 17th century throughout Europe and China, although it is not uncommon to find examples of crizzling in more recent objects. The term “sick glass” is often used to describe crizzling, but it is actually a general term that can be ascribed to more than one effect of deterioration in glass including fogginess, weeping, and the oily or wet residue left after exposure to high relative humidity. Glass that has these attributes and is kept in an environment that fluctuates in relative humidity will eventually crack because of the constant swelling and shrinking process that occurs when there are frequent switches between a dry environment and a more humid environment.
There are experimental treatments for crizzling including water based, ion solutions that are applied to the object to treat the surface of the glass. The second is a consolidant and adhesive agent, which in the past, has been an approach that was considered inoperable because of the agents’ ability to absorb and trap water. Trapped water under the surface of the consolidant can form salts under the agent’s coating and eventually cause flaking of the consolidant and further deterioration of the glass.
Nevertheless, despite these drawbacks to using consolidant and adhering agents to prevent and slow the process of crizzling, a new treatment involving a solution of 15 percent Paraloid B-72 has shown in experiments to work well at stabilizing glass objects prone to crizzling (Koob, S.P, 2010:128) .
Anonymous, 2011 Crizzling. Electronic document, http://www.cmog.org/article/crizzling, accessed 04/02, 2014.
Brill, R. H., 1975 Crizzling - A Problem in Glass Conservation. In Conservation in Archaeology and Applied Arts. Pp. 121. Stockholm Congress: International Institute for Historic and Artistic Work.
Hogg, Simon, David McPhall, Victoria Oakley, and Phillip Rogers, 2014 Cracking Crizzling - Eight Years of Collaborative Research. Electronic documnt, http://www.vam.ac.uk/content/journals/conservation-journal/issue-29/cracking-crizzling-eight-years-of-collaborative-research/.
Koob, Stephen P., 2010 An Experimental Treatment for Severely Crizzled Glasses. Glass and Ceramic Conservation:128.
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