My bowing must be horrible, but even when I slow down and try to be careful, sometimes the string will sound very “metallic” especially when crossing from D to A string, and lots of bows produce squeaks, squawks and you should hear the high whistle (?) the E string produces all too often, but especially if I’m moving fast. UGH. I would try to blame the violin but I’m on the 3rd one and it’s obvious the problem is ME. I guess I need to be perfectly perpendicular and flat? But I see players all the time that slightly aren’t, and they sound fine… well I’ve only been at it about seven months, maybe this will pass – but if I don’t know exactly what causes it – and fix it – maybe not, eh?