I recently purchased some small glass cabochons made in Czechloslovakia in the 1920's. They are basically flat-backed mini-sculptures with some substance in another color applied to them like a patina to accentuate the relief in the glass.
I set a couple of them in sterling settings I'd fabricated and then put them in my ultrasonic cleaner with warm water and "Magic Green" cleaner or dishwashing liquid. To my surprise, the "patina" came off.
So I took another one and washed it by hand in cold water with dishwashing liquid...the "patina" didn't come off.
I'd like to reapply this "patina" to cabs that it came off of.
Does anyone know what this stuff is and how it was applied? I would have to guess that the warm water is what removed it. I'd have to guess it wasn't a paint because it dissolved off, rather than flaking off, or if it was a paint, it was water-soluable in warm water only.
Thanks for any help you can give with this question. I know, it's a weird one.
Geri
1920's Glass question
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Geri Comstock
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could be anything. varnish, catalized linseed oil, shellac, etc.
what color was it? did it have any smell?
i'd suggest it was either the ultrasonic or the solvent cleaner, not the temp of the water.
you might try to remove it with a few different solvents from an existing one.
alcohol will dissolve shellac
lacquer thinner will (eventually) dissolve varnish
etc.
what color was it? did it have any smell?
i'd suggest it was either the ultrasonic or the solvent cleaner, not the temp of the water.
you might try to remove it with a few different solvents from an existing one.
alcohol will dissolve shellac
lacquer thinner will (eventually) dissolve varnish
etc.
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Geri Comstock
- Posts: 340
- Joined: Mon Mar 10, 2003 4:16 pm
- Location: Northern CA
- Contact:
To answer your questions...
The color was a greenish color (kind of like a Tiffany green patina, but on glass instead of metal). The glass was a coblat blue that kind of looks like lapis.
The patina doesn't smell, as far as I can tell, but it's about 75-80 years old so I'd guess any smell would have worn off by now.
I have other pieces with other colors of patina: red, yellow, brown, blue, green...
I can't imagine that the action of the ultrasonic cleaner removed the patina. They weren't rubbing on anything. They just vibrated for a while to get buffing compound off of them.
The patina can be buffed off using a buffing machine with red rouge buffing compound.
The pieces were in the solution very briefly (5 minutes or less) on different days in different cleaning solutions, but the water was very warm in both cases (my ultrasonic cleaner has a heater which helps with the cleaning process).
Shellac is water-soluable, isn't it? It was widely used on as a finish coating on furniture until the non-water soluable modern finishes were invented...don't know when that was, though.
Thanks in advance -
Geri
The color was a greenish color (kind of like a Tiffany green patina, but on glass instead of metal). The glass was a coblat blue that kind of looks like lapis.
The patina doesn't smell, as far as I can tell, but it's about 75-80 years old so I'd guess any smell would have worn off by now.
I have other pieces with other colors of patina: red, yellow, brown, blue, green...
I can't imagine that the action of the ultrasonic cleaner removed the patina. They weren't rubbing on anything. They just vibrated for a while to get buffing compound off of them.
The patina can be buffed off using a buffing machine with red rouge buffing compound.
The pieces were in the solution very briefly (5 minutes or less) on different days in different cleaning solutions, but the water was very warm in both cases (my ultrasonic cleaner has a heater which helps with the cleaning process).
Shellac is water-soluable, isn't it? It was widely used on as a finish coating on furniture until the non-water soluable modern finishes were invented...don't know when that was, though.
Thanks in advance -
Geri
paint? it can be removed ultrasonically, which actually works by creating small air bubbles under the 'stuff' to be removed.
shellac is used on lots of stuff, like pills and candy (m&m's, in particular). it's not water soluable, but is water permeable. it's applied by dissolving lac bug sweat in alcohol. it also comes in lots of different colors (reds, greens, yellows, browns, etc), can be tinted, and has been used for a long time. most varnishes and lacquers are a plastic, so may not have been in common use that long ago.
http://www.shellac.org/shellac.html
shellac is used on lots of stuff, like pills and candy (m&m's, in particular). it's not water soluable, but is water permeable. it's applied by dissolving lac bug sweat in alcohol. it also comes in lots of different colors (reds, greens, yellows, browns, etc), can be tinted, and has been used for a long time. most varnishes and lacquers are a plastic, so may not have been in common use that long ago.
http://www.shellac.org/shellac.html
Geri:
This is not in the way of help for your problem, but a comment. I have found that ultrasonic machines will remove liver of sulpher patinas, and so as a precaution would not use an ultrasonic on anything with a patina. I believe I have read this caution elsewhere also, but cannot remember the source. Sorry this isn't much help, but I hope you find a solution to reapplying the patina.
Regards,
Pat in Chicago
This is not in the way of help for your problem, but a comment. I have found that ultrasonic machines will remove liver of sulpher patinas, and so as a precaution would not use an ultrasonic on anything with a patina. I believe I have read this caution elsewhere also, but cannot remember the source. Sorry this isn't much help, but I hope you find a solution to reapplying the patina.
Regards,
Pat in Chicago