Re: glass beads

[Deborah Bede <stillwaterstudio@xxxxxxxxxxx>]

I did a fair amount of research into degraded glass beads a number of years
ago, and I'll try to accurately recall what I found.

Glass is composed of three primary ingredients, silica, a flux such as soda
or potash, and a stabilizer, usually lime.  When the proportion of the lime
is too low when the glass is formulated, the soda or potash remains water
soluble and is leached out of the glass by atmospheric moisture.  This is
the white efflorescence you often see on certain beads.  When a pH of 9 is
reached the silica network of the glass is attacked, resulting in cracking
and breakage.

Removal of the surface efflorescence is desirable to raise the pH, at least
temporarily.  Water is not suitable for this because it will leach out even
more of the soda or potash, and moisture retained in threads and fabrics
surrounding the beads will accelerate further deterioration.  Surface
cleaning with isopropanol or ethanol was the preferred method at the time I
did this research, this may have changed since then.

While immersion in water would not be the best choice for these beads, you
still might decide it is the appropriate choice for the textile as a whole.

Good luck!

Deborah Bede
Stillwater Textile Conservation Studio, LLC
196 Old Warner Road
Bradford, NH 03221
(603) 938-2310
(603) 938-2455 fax
stillwaterstudio@xxxxxxxxxxx