Come to part 2 of the way to stop dye bleeding in smocked infant clothing.
Commercial dye fixatives are often used by artists and companies that dye fabrics and understand the type of dye they are using to produce smocked clothing.
Dye fixatives are cationic, which means that they have a positive charge. The positive charge allows the fixative to cling to negatively charged dyes, such as the direct dyes and acid dyes for smocked infant clothes. They cannot stick to basic dyes, which have a positive charge, and have no benefit for colorfastness of smocked baby clothes for that type of dye.
You handwash smocked clothes separately or in a load with similar smocked dresses for baby girls or boys smocked clothing. I wash all blue jeans together and red smocked infant suits that can be washed at the same temperature.
You should use cold water will help the color last longer, sort your clothes before washing and learn how to remove dye transfer to other clothes safely.