For washing, machine wash the polyester part on a gentle cycle with cold or lukewarm water, while hand wash the delicate chiffon part using a mild detergent. Avoid bleach or harsh chemicals. After washing, gently squeeze out excess water and air dry the dress by laying it flat or hanging it on a padded hanger. If using a dryer for the polyester, use a low heat setting. When ironing, use a low to medium heat setting on the damp polyester part, and the lowest heat setting or steam for chiffon.