When sourcing satin dresses, the primary focus should be on the fabric composition and weight. High-end markets typically demand silk satin or high-grade acetate, while the mass market utilizes polyester satin. You must verify the fabric weight (measured in GSM) to ensure it provides the necessary drape and opacity. Additionally, check for colorfastness (Grade 4 or higher) and seam strength, as satin is prone to fraying and 'slippage' at the seams. Requesting a swatch card to feel the 'hand-feel' and luster is essential before bulk production.