What I remember about the starch from when I was kid (60 years ago)
The starch in the blue and white box - mixed with a little cold water to dissolve it (the mixture looked cloudy) - then hot or boiling water was added to it - and it got uncloudy - then a little square of a blue substance (it was Satina) was added.
The clothes were dipped in this great big bowl (it was the bread mixing bowl) and then wrung out - hung on the line to dry - then sprinkled with water, rolled up, and ironed later after they were evenly damp. (If that didn't happen by the next day, the clothes went into the freezer)
What needed to be stiffest was dunked first, because the starch solution got "weaker" as it was used.