Hi Jo. I don't believe dry cleaning with affect the thread. When I used to
do ring bearers pillows I used a heavy backing - 2.5 to 3 ounces. BUT that
was a pillow and not a dress. It might be worth a trip to the fabric store
to get a 1/2 yard of satin to play with to be sure. Ball point needles are
your best friend for this one.
Best wishes!
Judy
