While Radcliffe said it was 'vigorous and enjoyable', Watson found the experience 'awkward'.
The actress has admitted it was made tricky after producers told her at the last minute the snog was to be topless.
"I forgot how full-on it was until I saw the movie, and I was like, ''Blimey, where did that come from?'' It was really full-on," the Sun quoted her as saying.
"It was only the day before that they said, ''Oh, by the way, we hope it's all right, but we want you to be topless, and we're going to cover you in silver paint''.
"It was awkward enough as it was without the silver paint and the strapless bra, but whatever.
"It was like some weird social experiment," she said.
However, she added: "He is a good kisser. I can definitely vouch for that."
