I used to water marble a whole lot more. For some reason, my first ever attempt at marbling came out nearly perfect, and then after that I could never quite recreate my success. Beginners luck, perhaps? Besides, once I started getting better at other kind of art, I started feeling like marbling wasn't worth the hassle.
For the record, it totally is.
This was an interesting experiment for me, and it started by accident. I was marbling with silver and blue, and the silver was an extremely eager polish- it spread out like crazy, squashing the blue down to nothing. So I decided to break the rules of marbling- I double dipped. In some cases, I even triple dipped. And I loved the results!
It's so much easier this way, because you can afford to be sloppy and it won't ruin anything at all.
Silver- Revlon Sterling
Blue in marble- Cult Nails Time Traveler (which, for the record, marbles just fine, but Sterling overpowers it)
Blue on non-marbled nails- Maybelline Colorama 80