What kind of lining do 100% silk draperies need?  I purchased 100%
silk draperies with a fairly thin lining from JcPenney.com  They are
their new La Scala pinch pleat drapes.  If you want to check them out
online.  It consists of 70% polyester and 30%  cotton.  Is this
doable? Do I need a better,
thicker lining than these? I guess I'm trying to save a little bit of
money without having to have them custom made.  I hope someone has
some advice.

Ann,
The problem with silk is that it deteriorates in sunlight, that is
what the lining is for. It also gives the drapes more "body", which
custom curtain makers think is a good thing, though it is a matter of
taste, but good for their business.

I checked out the site, thank you.  Nice!  I would trust JC's choice
of lining material; it should be lighter in weight than the curtains,
otherwise they would look like they were just something hiding the
heavier lining.
I wouldn't consider investing in having new linings made.  Maybe there
is a better material for the lining, but the expense of having new
linings made  - I feel - would be unjustified.

No, I am no expert, but we have dupion silk curtains ("dupioni" in
JC's language), have had them for decades, at least three
"generations" by now, choosing to replace them when they deteriorate
as the cheaper solution to having them lined  (well, it is a lot
cheaper 'cause I sew them).
Myoarin