prespiration- stains on silk

["Andrea Lang" <ALang.RES.SPA.DHM@xxxxxxxxxxx>]

Dear colleagues,

I?m verry glad to have learned about this list from one of my 
colleagues in Berlin.
My name is Andrea Lang and I?m working at the Deutsches 
Historisches Museum as an textile conservator.
I have a problem with prespiration stains in a lady?s dress from 
the end of 19th century. It is completely made from silk. 
The prespiration has damaged the fibers in the ground fibric and 
in the lining, in the area below the arms. The fibers and the textile 
are broken, somewhere the fragments are broken out. The dye 
of the ground fibric are partial changed from brown to red and 
dark brown.

What happens? Which substance, contains prespiration, 
damaged the fibres? I took the ph, it is between 5 and 6, not a 
problem for silk, I think. Salts also contained. So the fiber will 
recept the humidity in the area of stains more than in the areas 
around it. This can result in stress and areas of weakness at the 
edge of the stains.
Now  the dress will undergo a conservation treatment because it 
will go into an exibition. Therefore a part of the arm seams have 
to be separate.This is the chance to remove the harmful 
substances. Do I have to remove it? 
Is there anyone who can help me with the cemical problem/ 
understanding? 
And is there anyone with  practical experience in removing stains 
from historical textiles? Is it possible, to remove without 
enlarging the area of the stain in silk?
On the other hand we have optimal climate conditions for our 
exebits in both, the storage areas as well as in the exebition. 

I woud be verry glad to get an answer,
Thanks,
Andrea Lang
Textilrestauratorin 
Deutsches Historisches Museum