Grout and adhesives can pop in the cold, put them inside for protection.

My regular gazing globes have been outside for several winters and they have survived my zone 7a winters with no problems. I have two bowling balls that I made into gazing balls using pennies on one and flat marbles on the other. The penny one is up on a metal pole so that it is off the ground and it survived outside last winter just fine. The one with marbles was on the ground and I noticed that quite a few of the marbles on the bottom of the ball fell off during last winter. It could be that the moisture from the ground interacted with the silicon adhesive and caused the marbles to pop off of it but I had no problem with the other one. This winter I am going to be taking the rest of the marbles off of it and do another penny one since I like it much better than the one with the marbles on it anyway.

Just a tip:

When I was attaching a soap dish to the shower wall with silicone, the label suggested wiping the wall surface with Denatured Alcohol to clean it before applying the silicone. I have since seen the same warning on other stuff. The cleaning apparently provides a slicker surface and a tighter fit.

So.... if you're making anything that is something like glass-on-glass (attached with silicone), it might be a good idea to wipe with the alcohol.

Of course, that doesn't help you now.....

'Pup

Pup, I did both my penny and marble bowling ball at the same time on old bowling balls from the bowling alley. I would think that a roughed up surface would be better than a slick one for attachment of anything to another surface so that the surface would have some tooth to grab the silicone. In fact, I have since seen where people recommend that you take sand paper and sand the balls lightly before attaching anything to them. I didn't rough up either of the balls that I did but they were pretty beat up from use. I still think the problem with the one on the ground was an issue with moisture getting into areas and the freeze thaw cycle pulling the marbles off especially since the ones that fell off were in proximity to the soil and the ones not in proximity to soil stayed on.

As to the other real gazing globes in my yard, I have both the glass type and the thinner mirrored ones and the mirrored ones definitely need to have their ends sealed or the mirroring material with eventually come off leaving you a pretty globe with no mirroring effect.

At the museum where I work, we use alcohol to clean an object to get rid of any oil, grease or just oil from your hands. We use the alcohol to clean the area where it will be marked. ggks

My gazing ball survived one winter held up by a very small wire plant support. But the second winter, it was shattered by hail.

I heard that bowling bowls are so full of grease from ??? (must be the machinery) They should be cleaned/heated, bring out all the oils before mosaicing. My sister did her garden in bowling balls and they got all chalky and cracked in the sun after a while. Really interesting.

Jo