capacitors as soft start on AC motor

my friend has a paddle mixer for mixing building materials.

its currently on a variable speed trigger, for some reason he wants it just as an off an on switch with a soft start. i told him to cable tie the trigger....but he doesnt want to do this.

being a cheap person. i wonder if a large capcitor on the motor would work as a soft start instead of a proper soft start circuit.

i know this works on DC motors.....doe it work the same on AC motors?

i was thinking something like a large microwave capcitor as i have a few to hand.

any help on this topic would help.

TIA
jim