How long does it take the pepper spray to work and how long will the effects last?

i got one of those for my girlfriend for when im not around and sprayed it on my self to check the effects sprayed into face and onto arms it burns terribly on the arms little less on the face had no problem with the eyes lasted for twenty minutes or so it did hurt but nothing that would stop me if say i wanted to mug or rape you better go with a knee to the groin

it works instantly and it last for several hours or until it is thoroghly washed out from the effected areas