I always have a laugh when I pop in on local rug dealers either here in Bahrain or Kuwait, and spot the (obvious to me) fake silks from Kashmir or elsewhere, and then listen to them try to pass them off as real silk... Unfortunately there are people that fall for the salesman's patter, and it's unfortunate that salesman feel the need to lie to make a buck (or do they really believe they are real silk?). But, hey, that's what provides the market niche opportunity for me - to give potential buyers the facts, and (I'd like to think) someone they can trust.
Here's a copy of a recent email I received from a usergroup which covers how to test for real silk. (There's a link over on the right side panel to an article which covers this subject also).
Tests for Silk
OK, you're looking at a nicely woven, nicely patterned, closely clipped
"silk" rug with what appears to be real silk fringe. You still might be
looking at a rug made of artificial silk. Here are three field tests that
might help you distinguish real from fake. No guarantee; your mileage may
vary.
Rub it! It is sometimes claimed that you can tell real silk from artificial
silk by vigorously rubbing the pile with your open palm. The real silk rug
feels warm, the artificial silk rug stays cool to the touch. We sometimes
think we have felt this difference. Of course, it helps to have a real silk
rug with you so that you can compare a known quantity!
Burn it! This test is at least good theatre, and actually can be helpful.
Clip off a small piece of the fringe, or pull a knot out of the rug from
the back (why should the owner object?). Burn it. Look at the ash and smell
the smoke. If the material was cellulose (rayon), the ash should be soft
and chalky, and the smell should be like burning paper (most paper is made
of cellulose). If the sample is real silk, the burning sample should ball
to a black, crispy ash, and the smell should be of burning hair (you're
burning protein, the same stuff your hair is made of). You've got to be a
little careful with this test to avoid smelling the smoke from the match
(and to avoid igniting yourself or the rug dealer's shop).
Dissolve it! The most accurate test is one that chemically differentiates
protein from cellulose or petrochemicals. One such test: at room
temperature, mix a solution of 16 g copper sulfate (CuSO4) in 150 cc of
water. Add 8-10 g glycerine, then caustic soda (sodium hydroxide: NaOH)
until a clear solution is obtained. This solution will dissolve a small
sample of natural silk, but will leave cotton, rayon, and nylon unchanged.
also:
SILK BURNS ONLY AS FAR AS ON FIRE SOURCE, WHILE NYLON ONCE FIRED WILL BURN
UP TO END.... AND MORE IMPORTANT WHEN SILK BURNS, IT SMELLS LIKE A BURNED
INSECT.
Take a container of bleach put a little into the cap....take a fiber and
place it in the bleach....if it disappears within about 20 seconds its
probably silk. If it is still there after 5 min...you know its not
silk...the color of course will change, but the fiber will still be there.
It is not 100% conclusive but its fast and inexpensive
From the ASCR Fiber & Fabric Forensics class textbooks:
- A 5% concentration of sodium hypochlorite @ 20 degrees C, will dissolve
silk in 20 minutes.
- A 60% concentration of sulfuric acid @ 20 degrees C, will dissolve silk
in 20 minutes.
- Silk will also dissolve in solutions of zinc chloride, calcium chloride,
alkali thiocyanates, and ammoniacal solutions of copper or nickel.
J. Burke, C.R.N.
( Certifiable Rugnut )
www.rugmates.com
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