Alumiuv cracking

Hi,

I've just started using the alumiuv for coating wooden rings, it cures fine (though i often need to leave it under the uv light for up to an hour to become completely solid, i've also left it in there for a few hours sometimes) it also looks perfect. I accidentally dropped one on the kitchen tiles a few weeks after it had been cured and it cracked. I then tried dropping a few more and they all cracked, once its cracked the alumiuv just chips off quite easily. I'm confused because the video on the website shows a guy throwing a lure on the concrete and it's still fine. Is there anything i'm doing wrong here or any steps i can take to ensure this doesn't happen?

I'm applying it straight onto the smoothly sanded wood bands - is there something i could put underneath the alumiuv coat maybe?

Thankyou,

Claire