Conservation of a Venetian Goblet

The treatments we do in the conservation lab range from simple to very complicated. This is a relatively simple treatment I recently finished.

54.3.15 before and after treatment

The foot on this Venetian goblet broke. To repair it the break edges were carefully cleaned. The fragments were then taped into position and an epoxy resin was dripped onto the joins.

 

epoxy going into joins through capillary action

The epoxy gets wicked into the joins through capillary action. Air trapped in the joins reflects light. Where epoxy has replaced the air, the joins disappear.

The glass and the epoxy were both warmed slightly in an incubator oven (to about 50° C) to help the epoxy flow better.

goblet getting warmed in incubator oven

The end result looks great! The joins become almost invisible because the refractive index of the epoxy matches the glass closely, whhich means that the glass and the epoxy reflect, absorb, and transmit light in the same way.

detail of foot after treatment

-Astrid van Giffen, Assistant Conservator

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Astrid van Giffen is the Museum's associate conservator. In 2007, she completed the conservation training program of the Netherlands Institute for Cultural Heritage (ICN) in Amsterdam, with a specialization in glass and ceramics. Her training included internships at the Walters Art Museum in Baltimore, Md,, and The Corning Museum of Glass in Corning. Since completing the ICN program, she’s worked as a private conservator in Oregon and was the Samuel H. Kress Fellow in Objects Conservation at the Straus Center for Conservation and Technical Studies of the Harvard Art Museum (2008-2009). She also holds a BA (2001) in Classical Studies from Willamette University.

2 comments » Write a comment

  1. Astrid,

    Can you comment on the use of the incubator? Does this reduce the viscosity of the epoxy? Are you using HXTAL? Would you recommend this technique on a blind crack?

    Thanks,
    Mark

  2. Hi Mark,
    The incubator oven is used to slightly heat the glass and the epoxy. Heating the epoxy does reduce its viscosity so that it initially flows almost like water. This allows it to penetrate further into the breakline or crack. Heating the epoxy also speeds up the setting time. You must pay close attention to how long it is heated because it will become more viscous as it sets. It also because more viscous when it cools again. This is why the glass is heated as well.

    This technique can be used for blind cracks. However, if the crack is very tight the epoxy may not penetrate completely. It could also cause the crack to propagate further. You should also be careful to not heat the glass too much as this could also worsen the crack.

    For this goblet HXTAL was used, which is what we use for most soda-lime glasses. For lead glasses we use Epo-tec 301-2 which has a slightly higher refractive index and therefore is a better match.

    I hope this helps!
    Astrid

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