Re: Printing on fabric

From: Loris Medici <loris_medici@yahoo.com>
Subject: RE: Printing on fabric
Date: Thu, 11 Mar 2004 07:53:55 +0200

> > You should never use soap with silk, just soak it in water and change
> > the water many times. If your water is basic, add some drops of lemon
> > acid.
>
> Will try to pre-wash with 0.5% sulfuric acid (5ml to 1lt) and then rinse
> reveral times...

I didn't see anyone mentioning what chemical component is responsible
for fog formation, but since you are talking about cyanotype, some
iron compounds get suspicion. Did anyone look up whether iron is
present in silk? The easiest and most sensitive test for iron I can
think of right now is...

Wash sample silk in dilute sulfuric acid thoroughly with good
agitation. To the solution (sample silk may remain), add a bit of
potassium thiocyanate. If you see blood-colored reaction product,
iron is present. (detects ferric ion)

Although less sensitive, you can add potassium ferrocyanide to the
sample silk, and if you see familiar prussian blue reaction product,
iron is present. (detects ferrous ion)

Let me know if any of these tests come out to be positive... Washing
silk in EDTA, DTPA, sodium salicylate, citric acid, etc. is effective
in washing out iron, if this is indeed the cause for trouble.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)