Guilding question

Hi ! I guild some sterling silver rings with this formula.

3.6 gr of gold cyanide per liter
3.6 gr of potasium cyanide per liter
3.6 gr of disodic phosphatem per liter

2.0 volts for 40 seconds, it guilded very nice, I soaked in
water. When I rub strongly the piece with my fingers the guild
started to fade. I supose that if it is for a ring the gold would
come off in 3 or 4 days.

What I’m doing wrong ?, Should I leave the piece longer, 1 min
or more ?, Is the formula right ?

Thank you very much !