Silk Organza is one of the best fabrics to use as underlining.
Underlining vs. lining
Lining and underlining a garment are two different procedures, and depending on their purpose, one or both can be used in a single piece of clothing. Usually cut from a slippery fabric, lining is attached only at the garment’s waistband or neck, and sometimes its hem — otherwise, it hangs free in the garment. It’s generally used to give a finished look to the inside of the garment, prevent seams from raveling, reduce wrinkling, help conceal some figure faults, and make a garment easier to slip on and off.
Underlining, on the other hand, is cut from the same pattern pieces as the fashion fabric and is attached before construction begins. Then, as the garment is constructed, the underlining and fashion fabric are handled as a single unit.
Most often, underlining is cut from fine cotton batiste, light- to medium-weight cotton broadcloth, or silk organza. But a variety of other materials can also be used.
Silk Organza in over 60 colors can be found at http://www.fabrics.net/Silk-Organza-s/83.htm
Pima Cotton Batiste in colors can be found at Fairytail Frocks and Lollipops http://www.fairytalefrocksandlollipops.com/category_29/Solids.htm