The salt crystals will not contain any of the heavy metals, but will be the water soluble alkalis that are leaching out (we have analyzed numerous examples). Also, as far as I know, no glassmakers in Murano are working with lead glass.
The slippery slimy condition is not unusual for this period, as many contemporary glass artists are either making their own batch glass or modifying commercial batch glasses. This hydration is commonly called "weeping", and I do recommend it be cleaned off and not remain on the glass (as eventually it can build up and start to dissolve the silica). The higher quantities of alkali is usually at the cost of decreasing the amount of stabilizers and this is done for several reasons: to modify the visual effects and alter the working properties of the glasses. Glasses with higher amounts of alkali are easier to work, and stay more fluid for a longer time without re-heating. This is a great advantage for producing a large piece or a complicated piece. We have seen similar problems with other European productions, and glass from China as well. We have a significant amount of Fred Wilson sculptures in our collection, and I have not seen any problems with them yet. But we do take care to keep optimum storage conditions (45 % RH + 5). ------------------------------ Stephen Koob Chief Conservator Corning Museum of Glass Corning NY (607) 329-8880 ------------------------------ ------------------------------------------- Original Message: Sent: 10-14-2019 19:15 From: Monona Rossol Subject: Contemporary Murano chandelier weeping You said, "The glass is coloured, predominantly blues, greens and yellow." That means the salt crystals could not only contain lead but cadmium, chromium, cobalt, and a host of other toxic metals. Was any of the weeping and crystal material kept? Monona Rossol Original Message------ Dear Trude, At the National Museums Scotland we have treated 3 pieces of contemporary designed Murano glass vases designed by Michele de Lucchi for Memphis, Milan, and made by Toso Vetri d'Arte, dating from 1983 which have shown evidence of weeping and formation of salt crystals. The pieces are on display , we washed the glass to remove surface salts and dried them. and have displayed them at 40% RH using passive control ( conditioned pro-sorb cassettes). The vases have been on display for 4 years , we continually monitor for signs of redeveloping weeping but as yet not observed anything . The glass is coloured , predominantly blues, greens and yellow. ------------------------------ Charles Stable Artefact Conservator National Museums Scotland Edinburgh 4401875614657 ------------------------------ Reply to Sender : https://community.culturalheritage.org/eGroups/PostReply/?GroupId=481&SenderKey=c6faae87-81ec-485d-b9ad-1afe4cf2fac1&MID=9196&MDATE=756%253e46546%253d&UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e Reply to Discussion : https://community.culturalheritage.org/eGroups/PostReply/?GroupId=481&MID=9196&MDATE=756%253e46546%253d&UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e You are subscribed to "Global Conservation Forum (ConsDistList)" as [email protected]. To change your subscriptions, go to http://community.culturalheritage.org/preferences?section=Subscriptions&MDATE=756%253e46546%253d&UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e. To unsubscribe from this community discussion, go to http://community.culturalheritage.org/HigherLogic/eGroups/Unsubscribe.aspx?UserKey=d16eaa87-0f69-494b-9f2f-303dbc1222e1&sKey=fab9aa4f27a04c5d876e&GroupKey=757a8f16-505f-4323-8e74-e376757aa9f7.
