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MOP adhesive


#1

Hi Orchid Jewelers I live in Australia and as a conservator do
other things besides jewelry. One thing I am working on and
which jewelers might have knowledge of is mother of pearl. The
mother of pearl in question is in the form of letters and stuck
to the back of a glass panel with paint around it. I need to
remove the letters as the glass is smashed. Now, I know what
adhesives are used nowadays in jewelery and guitar inlays but
does anyone know what would have been used in the early 20th
century? The one letter which is loose has traces of something
which looks (a) as though it didn’t spread very well, it’s in
lumps and (b)is a golden/browny colour. What was used in jewelry
and inlays in that era - any ideas? Or, if you don’t know can
you point me in any direction - you all seem very knowledgeable
and helpful. Thanks in advance Hilary


#2

I am totally unfamiliar with adhesives used on glass in the
1920’s but from the color and description two things come
immediately to mind. The first would be an animal based glue,
had to be heated and melted to be used. If the window were in
full sunlight though I would bet on a shellac as adhesive.
Denatured alcohol will dissolve that one. Norman


#3

Hide glue has been around a long time and fits the description
although we’ll see what some of the other Ochidians think.

John


#4

Hilary; One of the earliest forms of glue is animal hide glue.
Made from hooves and hide that has been boiled down to a fine
gelatin like paste. It dries to a tan to brown color and usually
a inconsistant thickness due to corse grinding of the materials.
Sounds like your glue. Try soking it in warm water over a couple
of days and see it the glue doesn’t soften. Frank Goss


#5

It may be something like pitch, which can be removed with
lacquer thinner, which will not affect the mother of pearl. I
also do a lot of restoration on 17th and 18th century english
silver, therefore I come across a lot of things. The lacquer
thinner will ofcourse affect the paint on the glass, but if you
that does not matter then go ahead. The thing you must be
careful with is heat on the mother of pearl, it can burn easily.
Do not put a flame directly on the mother of pearl. If it were
on a backing of metal, you could just heat the metal, and the
mother of pearl would lift off. If all you are interesting in
saving is the mother of pearl and the glass does not matter,
then slowly heat the back of the glass, by putting the glass on
a piece of copper sheet metal, either over a low torch or an
electric burner. Once you have removed the MOP, you can now
scrap off the rest of the pitch like substance with a wooden
tool, like a toothpick. I use tin oxide to give the MOP a nice
new surface polish. Ofcourse use ventilation, goes without
saying, I guess. So good luck . Ruth Rhoten


#6

Hillery,

In the early 20th century they used four types of adhesive for
binding. The first one is silicate binding with chalk This is
mostly used for putting a decanter into its silver feet. The
colour is white to light brown. This is only to solve in an acid
solution. The second on adhesive is bases on tar or kohl tar.
This is a black adhesive. mostly used ship repair and cheap
boxes. the third one is bone glue, mostly used for wood,
furniture, the colour is light to dark brown. this can be solved
in warm water. The fourth adhesive that was available in that
time was shellac. I think this is the one they used on your
bottle. This has normally a golden brown colour. The way to
remove, is to heat your parts up, above 80 to 120 degr Celsius
(depending on the added filling in the shellac) and it will come
of. The other, maybe safer way, is to solve the shellac into
alcohol. the best is ethanol or methanol, this does not affect
the mother of pearl.

Success,
And if you want to now more, don’t hesitate to ask
Martin Niemeijer