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Accidentally stained sea glass when heated


#1

Okay, unlike the smoking amber, I took even more precautions with a
bezel set piece of sea glass. I discovered, after setting it, a wee
problem in one area of the skirting around the bezel so I coated the
glass and the bezel with Extra Hands and held my breath, and tried to
gently sneak up on the area to just get the solder to flow a bit
more. I chicken out part way thru, noticed how dark the ring shank
had become and parts of the heat shield. Waited it to cool before
exposing the bezel. Only to find that I had severely discoloured the
glass! It is a grimy, grimy colour. Scrubbing has produced zero
improvements. Nor has vinegar and baking soda (works on my clogged
sink - ha!). I cut the glass out and it is more darkly discoloured
around the bezel, but still most of the piece is discoloured. Out of
curiosity, what happened? Was it a form of staining from the Extra
Hands? Or did heat still get thru to it and somehow affect the
glass? I did an Internet search, and kept coming up with hits on
stained glass windows etc though I did see something about using a
silver stain to colour glass. I also read about slumping glass and
glossy glass at high temps, but none of this occurred. I also didn’t
notice any cracking of the glass piece. Curious minds need to know!

Thanks in advance for your help!
Ros


#2

Instead of using the word “stain” you might try discoloured. In
bottles, soaking in water with crushed egg shells and occasionally
shaking them and swirling them will eventually get rid of
discolourations. You might try the same with the piece of glass in an
ordinary kitchen glass. (it can take days with old bottles) I googled
Extra Hands and got just as many strange results as you did with
stain! I have not a clue what it is and it seems, neither does
google.


#3

Ros,

One mistake…soldering anywhere near glass. I know glass people can
play with fire and glass ( I have), but the glass and jewellery gods
are not on speaking terms.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#4

Hi, you dont say what colour the glass was to start with nor do you
say what metal is was set in and both of these can have a
significant contribution to your problem.

Silver and especially silver oxide are used to colour glass, they are
the principal staining agents in old stained glass, giving blacks,
browns, white and yellows. Contact between a silver mount and the
glass will upon heating cause the glass to become stained and this is
permanent.

The colour of the glass, if blue, green or red will be due to
presence of metal oxides in the glass and these can change colour
with different oxidation states and by using a different
heating/cooling regime. Copper oxide will reduce and turn glasses
from blue or green to a grey/brown colour. Reds can go green or
yellow and sometimes even clear, depending upon the chromophore
(metal oxide colourant). Glass chemistry is as complicated as
mineral chemistry when it comes to colour so as with gemstones avoid
heat at all costs. I would say that the discolouration is permanent
and subsurface so unfortunately so chemical scrub will remove it
without causing damage toboth your metalwork and the glass itself.

Nick Royall


#5

Thanks, as always, Jeff for the response! Much appreciated. Something
in my gut told me to cut my loses, start over, but given that I
wasn’t in a hurry to finish this piece, and it was an expensive item,
I just had to try :)I saw someone making little pendant, with a photo
squished in between two pieces of clear glass. Used stain glass
caming type of soldering for the edges, I believe…actually, I
think that it was with a soldering iron now that I concentrate more.
Hmmmm. Cheers Ros


#6

Thank you Nick - that really helps to explain things - I was using
Argentium silver on a piece of sea foam green glass. Darkened the
glass as well as gave it an amber tone. So it is a good chance that
it was the contact with the silver, albeit at a temp that did not
cause it to crack, rather than the heat shield, which is good to
know for future projects.

Much appreciated!
Ros


#7

If you are using a propane rich environment to solder, it is probably
the scuz caused when the propane is too high. Sometimes just turning
the oxygen up for a little bit will take the scuz off. Be careful not
to melt the glass though. Acetylene is a real dirty gas to use on
glass, it isn’t usually used in glasswork, so try turning the the oxy
up and see if that helps also. It is possible to burn the glass and
cause the scuz to become permanent. Some people use a single
tank-fuel for glasswork and solder, like MAPP or propane. Those are
harder to add oxy to. If you still can’t get the scuz off the glass,
instead of wasting your work, protect the metal and etch the glass
with some etch-all. It might hide it and just make it look like part
of the design.

Val


#8

Just normal drain opener lye (sodium hydroxide) will clean off most
anything and not harm glass. Use a Pyrex and protect your eyes. It
can and will cause chemical burns. It does work better warm or hot,
but again, careful of spatters. Just pour it down your drain. It’s a
great maintenance for your plumbing. If I’ve burned crud onto a stone
do to improper cleaning before soldering, I’ll use lye to clean up.
Works every time and safe for all metals excepting aluminum.


#9

Thanks for the extra info Val - I was using my acetylene/air torch.
My only other options for torches are propane only or mapps gas. Am
really nervous about reheating bands etc with glass in the bezel, if
this is the potential outcome…

Cheers
Ros