On trying them out I am very impressed by both the effect and the consistency of the polishes. They dry really quickly and were pretty much opaque with just one coat (although I applied two).
The only downside is that you can see the brush strokes on the nail which somewhat takes away from the foil effect...but maybe I was a bit clumsy with my application!
Barry M Instant Effects - Silver Foil no.319
Barry M Instant Effects - Gold Foil no.320
Have you tried the Barry M foil polishes or have you had a go at nail art foils?