Sorry I can't help but I just used GE Silicone II and it has held up fine outdoors.

Donna in Florida

The first 2 BBs I ever made, I used Liquid Nail brand 100% silicone and all the marbles (glass globs) fell off.

Nursemaid,

I've never heard of the copper colored Liquid Nails. I used GE Silicone II clear (I think mine is door and window) and it's been outside for about 4 years now. IT's all still holding up really well. I sprayed my BB with a green (verdigris color) car paint and then two layers of pennies. I know my Mom used to use the liquid nails. Sometimes it worked--but not always. I really don't know the trick with the LN. Whatever you do make sure you use just enough so it don't ooze out from behind the pennies.
Let us know what you finally use and show off a picture of your completed Penny BB!
Love, Jules

i used clear silicone for all my bowling ball/gazing balls and they're all holding up great. I do need to bleach them once or twice a year,though; but I live in the very hot and humid south. I used one layer of pennies, then got impatient for the green patina and sponged it with vinegar and salt for instant aging.

I'll stick with the GE II then. Thanks everyone :)

Donna