Goldenbow talks of slippage. That's a little vague - occasional slippage, permanent slippage? If occasional, it's more likely to be bad bowing technique - too fast a bow with too little pressure for the soundpoint. This might also account for why goldenbow wants to weight the tips of their bows to improve tone. I can't remember the last time I rosined my bow. Start of April? But I only played 8 or 9 times in April. During the weekend I intended to rosin it on Tuesday before orchestra so that it would have worn off a bit for my lesson today, but I forgot. So I'm going to a lesson today with a bow I might not have rosined since March. That's not one of the things I'm afraid of!