We have used spray silicone for over 12 years. We apply it to the top of the trailing curling shoe this helps to decrease the drag on the trailing foot. Apply it so that it will have 24 hours to dry.
We also use it on the pivot point on our swivel brooms, it is used to stop friction in the joint when sweeping. If you can reduce the friction in the sweeping motion more sweeping action is acheived.
We have also applied to the slider of our curling shoes, let it dry for 24 hours before using. This increases the speed of the slide and gives less resistance on the ice. We have never noticed any problem or effect with this being used " to the ice".