Last Updated: Dec 21, 2017     Views: 653

The film you describe is caused by the atmospheric deterioration of glass, known as "crizzling" or glass disease.

A few pages from Stephen P. Koob's book, Conservation and Care of Glass Objects, 2006, pp. 117-120 are very relevant. Koob explains why some glass crizzles and describes the initial stages in these pages.

I checked with Mr. Koob (who is our Conservator at CMoG). He added that we don’t use the word “oily”, but “slippery, slimy" feel. "It’s the alkali leaching out, so it’s slippery like soap (another alkali)."

Please let me know if you have additional questions.

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Comments (1)

  1. Is glassware that has leached this slippery film safe to use (after washing it, of course), or is it advisable to throw it away? Should I be worried about food storage in certain glass jars? I can't seem to find any information on this that talks about whether glassware that leaches alkali is hazardous.
    by Debbie on Aug 17, 2017.