My aunt would crochet fancy lacy baskets and starch them with a sugar mixture. I found a recipe for it online:
Sugar Starch Recipe for doilies: This is the old-fashioned starch used for lacy doilies.
1/4 cup water
3/4 cup granulated sugar
Mix water and sugar in a small pan. Stir the mixture over low heat (do not boil) until clear and not sugary. Remove pan from heat, and let mixture cool.
Wet the collar and cuffs of a blouse or lace doily. Roll in a towel to remove excess moisture and dip it into the mixture. Squeeze out excess starch, then shape the collar and cuffs or doily. Allow to dry and iron on warm setting.
Doilies do not need to be ironed when you use this starch. Just smooth out and shape while wet on a clean flat surface.