Why is there a foam head that developes during mash somtimes and not others?
and
Dose the mash time effect beer flavor? assuming there is good conversion

One question for the kettle also:
I have heard that some brewers skim the foam of the top of the wort before the boil!? Is this nessisary or will a vigerous boil break down what ever this stuff is?

Thanks for your time
Cheers
Curious