Depends on your breasts as to how painful it is. If you’re still quite firm, then you’ll probably find it more uncomfortable.
Your breasts are basically squashed individually from 3 different directions till they’re approx 5cm. You’ll be adjusted into the correct standing position, with your arm raised and on the machine.
I find them very uncomfortable almost to the point of painful, but as long as I stay relaxed and do my deep breathing I’m ok. They don’t take very long.
I personally wear clothes which are quick and easy to take off and on, and remove my jewelry before and put it in my bag.
I go every 12mths due to family history, so think I’ve had 8? and started before the age of 50.