Good Mask De-fogger?

Hi, had awful problems on holiday and in general with my mask fogging
up. Have used toothpaste twice, use spit before the dive and still not
great. Bought another mask as the previous one wasn't great really and
that was 100 times better. Used toothpaste again and still great but
after 6 or 7 dives started fogging even after more paste. Are there
any good de-fog solutions that work pretty well? Have always been
against using them really but if they keep my mask clear i'll happily
use them. Makes the difference between a good dive and an annoying
one!

Cheers all,

Rob
.