What is considered "true" heirloom sewing?
Heirloom sewing is a collection of sewing techniques seamstresses used up into the 1920's. If you've heard the terms "rolled hem", "entredeux", "french lace", "swiss embroidery", "whitework", etc., you've heard descriptions of heirloom sewing. Sewing, at that time, was done by hand. Garments, linens, etc., were created from natural fabrics (cottons, lawns, linens, silks, etc. - there were no synthetic fibers) and embellished with different types of embroidery. Hand-smocking was very popular in clothing, especially childrenswear.
Today, heirloom style garments may be created with techniquess used on sewing machines, to recreate the same look. For your item to be considered truly "heirloom", it should be created from all natural fabrics. For storage, use acid-free tissue paper, in a breathable container or chest. Some individuals also wrap their items in cotton sheets.